Tecumseh LAV30-50, V40-80, TVM125-220, HSK30-70, HH40-70 User Manual

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TECUMSEH

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T E C H N I C I A N ' S H A N D B O O K

This manual covers engine models:

ECV100 - 120, H22 - 80, HH40 - 70, HHM80, HM70 - 100,

HMSK70 - 110, HMXL70, HS40 - 50, HSK30 - 70, HSSK40 - 50,

HT30 - 35, HXL35, LAV30 - 50, LEV80 - 120, TNT100 - 120,

TVM125 - 220, TVXL170 - 220, TVS75 - 120, TVXL105 - 115,

V40 - 80, VH40 - 70, V60 - 70, VM70 - 100

Model numbers are located on the engine shroud.

3 TO 11 HP 4-CYCLE

L-HEAD ENGINES

CONTENTS

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CHAPTER 1 GENERAL INFORMATION ......................................................................................................... 1

ENGINE IDENTIFICATION ............................................................................................................................... 1

INTERPRETATION OF MODEL NUMBER ...................................................................................................... 1

SHORT BLOCKS .............................................................................................................................................. 2

FUEL ................................................................................................................................................................. 2

ENGINE OIL ..................................................................................................................................................... 3

TUNE-UP PROCEDURE .................................................................................................................................. 3

STORAGE ........................................................................................................................................................ 4

CHAPTER 2 AIR CLEANERS ........................................................................................................................ 5

GENERAL INFORMATION ............................................................................................................................... 5

OPERATION ..................................................................................................................................................... 5

COMPONENTS ................................................................................................................................................ 5

TROUBLESHOOTING OR TESTING .............................................................................................................. 5

SERVICE .......................................................................................................................................................... 6

DISASSEMBLY PROCEDURE ......................................................................................................................... 6

POLYURETHANE-TYPE FILTER ELEMENT...................................................................................................6

PAPER-TYPE FILTER ELEMENT .................................................................................................................... 6

CHAPTER 3 CARBURETORS AND FUEL SYSTEMS ................................................................................... 7

GENERAL INFORMATION ............................................................................................................................... 7

OPERATION ..................................................................................................................................................... 8

FUEL PRIMERS ............................................................................................................................................... 8

IMPULSE FUEL PUMPS .................................................................................................................................. 9

FLOAT STYLE CARBURETORS ..................................................................................................................... 9

DIAPHRAGM (PRESSURE DIFFERENTIAL) CARBURETORS ..................................................................... 9

COMPONENTS .............................................................................................................................................. 10

CARBURETOR IDENTIFICATION ................................................................................................................. 11

DUAL SYSTEM CARBURETORS .................................................................................................................. 11

SERIES 1 CARBURETORS ........................................................................................................................... 11

SERIES 3 & 4 CARBURETORS..................................................................................................................... 11

DIAPHRAGM CARBURETORS ..................................................................................................................... 11

SERIES 6 CARBURETORS 4-CYCLE ........................................................................................................... 12

SERIES 8 ........................................................................................................................................................ 12

SERIES 9 ........................................................................................................................................................ 12

SERIES 10 (EMISSION) ................................................................................................................................. 12

NON-TECUMSEH CARBURETORS -- DELLORTO CARBURETOR........................................................... 12

ENGINE TROUBLESHOOTING CHART ....................................................................................................... 13

CARBURETION TROUBLESHOOTING CHART ........................................................................................... 14

TESTING ........................................................................................................................................................ 15

SERVICE ........................................................................................................................................................ 15

CARBURETOR PRE-SETS AND ADJUSTMENTS ....................................................................................... 15

FINAL ADJUSTMENTS (NON-EMISSION ENGINES) .................................................................................. 16

NON-ADJUSTABLE CARBURETOR ............................................................................................................. 16

DISASSEMBLY PROCEDURE ....................................................................................................................... 17

FLOAT STYLE CARBURETORS ................................................................................................................... 17

DIAPHRAGM CARBURETORS ..................................................................................................................... 19

FLOAT ADJUSTING PROCEDURE ...............................................................................................................19

INSPECTION ..................................................................................................................................................20

ASSEMBLY ..................................................................................................................................................... 21

STANDARD SERVICE CARBURETORS .......................................................................................................24

CHAPTER 4 GOVERNORS AND LINKAGE .................................................................................................26

GENERAL INFORMATION ............................................................................................................................. 26

OPERATION ................................................................................................................................................... 26

INTERNAL COMPONENTS (VARIOUS STYLES) ......................................................................................... 26

TROUBLESHOOTING .................................................................................................................................... 26

ENGINE OVERSPEEDING ............................................................................................................................ 27

ENGINE SURGING ........................................................................................................................................27

SERVICE ........................................................................................................................................................ 27

GOVERNOR ADJUSTMENT .......................................................................................................................... 27

GOVERNOR ADJUSTMENT PROCEDURE FOR SHORT BLOCK INSTALLATIONS ................................. 27

C Tecumseh Products Company

1998

GOVERNOR GEAR AND SHAFT SERVICE .................................................................................................28

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SPEED CONTROLS AND LINKAGE ............................................................................................................. 29

CHAPTER 5 REWIND STARTERS ................................................................................................................ 35

GENERAL INFORMATION ............................................................................................................................. 35

OPERATION ................................................................................................................................................... 35

COMPONENTS .............................................................................................................................................. 35

SERVICE ........................................................................................................................................................ 35

ROPE SERVICE ............................................................................................................................................. 35

RETAINER REPLACEMENT .......................................................................................................................... 36

STYLIZED REWIND STARTER (TVS, HM, TVM, TVXL), AND STAMPED STEEL STARTER

(HM, VM, TVM, TVXL) ............................................................................................................................... 36

STYLIZED REWIND STARTER WITH PLASTIC RETAINER ........................................................................37

STANDARD STAMPED STEEL AND CAST ALUMINUM STARTER (HM, VM) ............................................38

VERTICAL PULL STARTER HORIZONTAL ENGAGEMENT TYPE .............................................................. 39

VERTICAL PULL STARTER VERTICAL ENGAGEMENT TYPE ................................................................... 40

CHAPTER 6 ELECTRICAL SYSTEMS ....................................................................................................... 42

GENERAL INFORMATION ............................................................................................................................. 42

OPERATION ................................................................................................................................................... 42

STARTING CIRCUIT AND ELECTRIC STARTERS ....................................................................................... 42

CHARGING CIRCUIT ..................................................................................................................................... 42

CONVERTING ALTERNATING CURRENT TO DIRECT CURRENT ............................................................ 43

HALF WAVE RECTIFIER SINGLE DIODE .................................................................................................... 43

FULL WAVE RECTIFIER BRIDGE RECTIFIER ............................................................................................. 43

COMPONENTS .............................................................................................................................................. 43

BATTERY ........................................................................................................................................................ 43

WIRING ........................................................................................................................................................... 43

ELECTRICAL TERMS .................................................................................................................................... 44

BASIC CHECKS ............................................................................................................................................. 45

TROUBLESHOOTING ELECTRICAL STARTER CIRCUIT FLOW CHART .................................................. 46

TROUBLESHOOTING ELECTRICAL CHARGING CIRCUIT FLOW CHART ............................................... 47

TESTING PROCEDURE ................................................................................................................................48

STARTING CIRCUIT ...................................................................................................................................... 48

CHARGING CIRCUIT ..................................................................................................................................... 48

VOLTAGE REGULATIONS ............................................................................................................................. 56

LOW OIL SHUTDOWN SWITCHES............................................................................................................... 56

SERVICE ........................................................................................................................................................ 57

12 VOLT OR 120 VOLT ELECTRIC STARTERS WITH EXPOSED SHAFT ................................................. 57

12 VOLT D.C. OR 120 VOLT A.C. ELECTRIC STARTERS WITH THE STARTER GEAR UNDER

THE CAP ASSEMBLY ............................................................................................................................... 57

INSPECTION .................................................................................................................................................. 58

CHAPTER 7 FLYWHEEL BRAKE SYSTEMS ............................................................................................... 59

GENERAL INFORMATION ............................................................................................................................. 59

OPERATION ................................................................................................................................................... 59

BOTTOM SURFACE SYSTEM....................................................................................................................... 59

INSIDE EDGE SYSTEM ................................................................................................................................. 60

COMPONENTS .............................................................................................................................................. 60

SERVICE ........................................................................................................................................................ 61

FLYWHEEL REMOVAL .................................................................................................................................. 61

BRAKE LEVER AND PAD .............................................................................................................................. 61

IGNITION GOUNDOUT TERMINAL...............................................................................................................61

STARTER INTERLOCK SWITCH .................................................................................................................. 62

CONTROL CABLE .......................................................................................................................................... 62

BRAKE BRACKET REPLACEMENT.............................................................................................................. 62

CHAPTER 8 IGNITION .................................................................................................................................. 63

GENERAL INFORMATION ............................................................................................................................. 63

OPERATION ................................................................................................................................................... 63

SOLID STATE IGNITION SYSTEM (CDI) ......................................................................................................63

MAGNETO IGNITION SYSTEM (POINTS) .................................................................................................... 63

IDENTIFICATION OF TECUMSEH IGNITION SYSTEMS ............................................................................. 64

COMPONENTS .............................................................................................................................................. 64

IGNITION TROUBLESHOOTING .................................................................................................................. 66

TESTING PROCEDURE ................................................................................................................................67

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SERVICE ........................................................................................................................................................ 68

SPARK PLUG SERVICE ................................................................................................................................ 68

CONDITIONS CAUSING FREQUENT SPARK PLUG FOULING .................................................................. 68

IGNITION TIMING PROCEDURE .................................................................................................................. 68

SERVICE TIPS ............................................................................................................................................... 71

CHAPTER 9 INTERNAL ENGINE AND CYLINDER ..................................................................................... 72

GENERAL INFORMATION ............................................................................................................................. 72

OPERATION ................................................................................................................................................... 72

4-CYCLE ENGINE THEORY .......................................................................................................................... 72

LUBRICATION SYSTEMS .............................................................................................................................. 73

COUNTERBALANCE SYSTEMS ................................................................................................................... 73

COMPONENTS .............................................................................................................................................. 74

ENGINE OPERATION PROBLEMS ............................................................................................................... 75

TESTING ........................................................................................................................................................ 77

ENGINE KNOCKS .......................................................................................................................................... 77

ENGINE OVERHEATS ................................................................................................................................... 77

SURGES OR RUNS UNEVENLY ................................................................................................................... 77

ENGINE MISFIRES ........................................................................................................................................ 77

ENGINE VIBRATES EXCESSIVELY .............................................................................................................. 78

BREATHER PASSING OIL ............................................................................................................................. 78

EXCESSIVE OIL CONSUMPTION ................................................................................................................. 78

LACKS POWER ............................................................................................................................................. 78

SERVICE ........................................................................................................................................................ 79

DISASSEMBLY PROCEDURE ....................................................................................................................... 79

CYLINDERS ...................................................................................................................................................81

CYLINDER HEADS ........................................................................................................................................ 82

PISTONS, RINGS AND CONNECTING RODS ............................................................................................. 82

CRANKSHAFTS AND CAMSHAFTS ............................................................................................................. 84

VALVES ..........................................................................................................................................................85

CRANKCASE BREATHERS ...........................................................................................................................86

CYLINDER COVER, OIL SEAL, AND BEARING SERVICE .......................................................................... 87

CRANKSHAFT BEARING SERVICE ............................................................................................................. 88

COUNTERBALANCE SERVICE .................................................................................................................... 89

FLYWHEEL SERVICE .................................................................................................................................... 89

CHAPTER 10 ENGINE SPECIFICATIONS ................................................................................................... 90

FOUR CYCLE TORQUE SPECIFICATIONS ................................................................................................. 91

ENGINE SPECIFICATIONS STANDARD POINT IGNITION ......................................................................... 93

SOLID STATE AND EXTERNAL IGNITION ................................................................................................... 97

CHAPTER 11 EDUCATION MATERIALS AND TOOLS ............................................................................. 102

DECIMAL / FRACTION CONVERSIONS ..................................................................................................... 105

SEARS CRAFTSMAN CROSS REFERENCE SUPPLEMENT INCLUDED IN BACK OF BOOK

iii

CHAPTER 1 GENERAL INFORMATION

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ENGINE IDENTIFICATION

Tecumseh engine model, specification, and serial numbers or (date of manufacture, DOM) are stamped into the blower housing or located on a decal on the engine in locations as illustrated (diag. 1 & 2).

NOTE: On some LEV engines, a cover bezel must be removed to provide access to the identification decal (diag. 1).

The engine identification decal also provides the applicable warranty code and oil recommendations (diag.

3). Emissionized engines that meet the California Air

Resource Board (C.A.R.B.) or the Environmental Protection Agency (E.P.A.) standards will include additional required engine information on the engine decal (diag. 3).

INTERPRETATION OF MODEL NUMBER

The first letter designation in a model number indicates basic type of engine.

V - V ertical Shaft LAV - Lightweight Aluminum Vertical VM - Vertical Medium Frame TVM - Tecumseh Vertical (Medium Fr ame) VH - Vertical Heavy Duty (Cast Iron) TVS - Tecumseh Vertical Styled TNT - Toro N’ Tecumseh ECV - Exclusive Craftsman Vertical TVXL - Tecumseh Vertical Extra Lif e LEV - Low Emissions Vertical H - Horizontal Shaft HS - Horizontal Small Frame HM - Horizontal Medium Frame HHM - Horizontal Heavy Duty (Cast Iron) Medium F rame HH - Hor izontal Heavy Duty (Cast Iron) ECH - Exclusive Craftsman Horizontal HSK - Horizontal Snow King

COVER BEZEL

MODEL AND

D.O.M. NUMBER

DECAL

LOCATED

UNDER COVER

(IF SO EQUIPPED)

PRESS IN AND LIFT

HERE TO RELEASE

COVER

HS50 67355H SER 4091D

The number designations following the letter indicate the

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horsepower or cubic inch displacement. The number following the model number is the

specification number. The last three numbers of the specification number indicate a variation to the basic engine specification.

The serial number or D.O .M. indicates the production date. Using model LEV115-57010B, serial 8105C as an

example, interpretation is as follows:

LEV115-57010B is the model and specification number LEV Low Emissions Vertical 115 Indicates a 11.5 cubic inch displacement

FUEL REGULAR UNLEADED

OIL, SAE 30 (BELOW 32oF SAE 5W30)

LEV115 57010B (D)

STP185U1G1RA

8105C

57010B is the specification number used for properly

identifying the parts of the engine

8105C is the serial number 8 first digit is the year of manufacture (1998) 105 indicates calendar day of that year (105th day

or April 15, 1998)

C represents the line and shift on which the

engine was built at the factory.

Engine Family: Engine Tracking Information

SHORT BLOCKS

New short blocks are identified by a tag marked S.B.H. (Short Block Horizontal) or S.B.V. (Short Block Vertical). Original model identification numbers of an engine should always be transferred to a new short block for correct parts identification (diag. 4).

THIS SYMBOL POINTS OUT IMPORTANT SAFETY INSTRUCTIONS WHICH IF NOT FOLLOWED COULD ENDANGER THE PERSONAL SAFETY OF YOURSELF AND OTHERS. FOLLOW ALL INSTRUCTIONS.

THIS ENGINE MEETS 1995-1998

CALIF. EMISSION REGULATOR FOR

ULGE ENGINES AS APPLICBLE

FUEL: REGULAR UNLEADED OIL: USE SEA30

LEV115 57010B (D)

STP185U1G1RA

8105C

SHORT BLOCK IDENTIFICATION TAG

SBV OR SBH IDENTIFICATION NUMBER

SBV-2316

SER 4291

SERIAL NUMBER

FUEL

Tecumseh strongly recommends the use of fresh clean unleaded regular gasoline in all engines. Unleaded gasoline burns cleaner, e xtends engine life and promotes better starting by reducing build-up of comb ustion chamber deposits.

REFORMULATED AND OXYGENATED FUELS

Reformulated fuels containing no more than 10% Ethanol, 15% MTBE, 15% ETBE or premium gasoline can be used if unleaded regular gasoline is not available . Leaded fuel may be used in countries where unleaded fuel is not availab le. NEVER USE FUEL CONTAINING METHANOL.

ENGINE OIL

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Use a clean, high quality detergent oil. Be sure original container is marked: A.P.I. service SF thru SJ. The use of multigrade oil may increase oil consumption under high temperature, high load applications.

NOTE: DO NO T USE SAE10W40 OIL. For summer (above 32°F, 0oC) use SAE 30 oil part # 730225 (1 quar t, .946 liter container) in high temperature, high

load applications. S.A.E.10W30 is an acceptable substitute. For winter (below 32°F, 0oC) use S.A.E. 5W30 oil part # 730226 (1 quart, .946 liter container) S.A.E.10W is an acceptable substitute. S.A.E. 0W30 should only be used when ambient temperature is below 0oF, -18oC.

CAPACITIES: EUROPA MODELS Engine Model Oz. mL. Oz. mL.

LA V30-50, TVS75-120, LEV80-120 21 63 0 V antage 21 63 0 ECV100-120, TNT100-120 21 63 0 Prisma 21 630 V & VH50, 60, 70 27 810 Synergy 21 630 TVM 125, 140 27 810 Synergy "55" 27 810 TVM & TVXL 170, 195, 220 32 960 Spectra 21 630 VM70, 80, 100 32 960 Futura 21 630 VH100 50 1500 Centura 21 630 H & HSK30, 35, HS & HSK40, 50 21 630 HTL 21 630 H, HH & HSK50, 60, 70 19 570 BVS 21 630 HM & HMSK70, 80, 100 26 720 BH Series 21 630

Geo Tech Series 35-50 21 630

Oil Change Intervals. Change the oil after the first two (2) hours of operation and every 25 hours thereafter, or more often if operated under dusty or dirty conditions, extreme temperature, or high load conditions.

Oil Check. Check the oil each time the equipment is used or every 5 hours. Position the equipment so the engine is level when checking the oil.

CAUTION: REMOVE THE SPARK PLUG WIRE BEFORE DOING ANY SERVICE WORK ON THE ENGINE.

Oil Change Procedure: Locate the oil drain plug. On some units this plug is located below the deck through the

bottom of the mounting flange. Other units drain at the base of the engine above the deck or frame. If access to the drain plug is restricted by the equipment it may be necessary to drain the oil by tipping the mower in a position that would allow the oil to drain out of the fill tube.

On units that the drain plug is accessible, remove the plug and allow the oil to drain into a proper receptacle. Always make sure that drain oil is disposed of properly.

Once the oil is drained, reinstall the plug and fill the engine with new oil to the proper capacity.

TUNE-UP PROCEDURE.

The following is a minor tune-up procedure. When this procedure is completed, the engine should operate properly. Further repairs may be necessary if the engine's performance remains poor.

CAUTION: REMOVE THE SPARK PLUG WIRE BEFORE DOING ANY SERVICE WORK ON THE ENGINE.

1. Service or replace the air cleaner as needed.

2. Inspect the level and condition of the oil and change or add oil as required.

3. Remove the blower housing and clean all dirt, grass or debris from the intake screen, cylinder head, cylinder

4. Make sure the fuel tank, fuel filter and fuel line are clean. Replace any worn or damaged governor springs or

cooling fins, carburetor, governor levers and linkage .

linkage. Make the proper governor adjustments and carburetor presets where required.

5. When replacing the spark plug, consult the parts breakdown f or the proper spark plug to be used in the engine being

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serviced. Set the spark plug gap to .030" (.762 mm) and install the spark plug in the engine. Tighten the spark plug to 15 foot pounds of torque (20.4 Nm). If a torque wrench isn’t available, screw the spark plug in as far as possible by hand, and use a spark plug wrench to turn the spark plug 1/8 to 1/4 turn further if using the old spark plug, or 1/2 turn further if using a new spark plug.

6. Make sure all ignition wires are free of abrasions or breaks and are properly routed so they will not rub on the flywheel.

7. Properly reinstall the blower housing, gas tank, fuel line and air cleaner assembly if removed.

8. Make sure all remote cables are properly adjusted for proper operation. See chapter 4 under "Speed Controls and Linkage".

9. Reinstall the spark plug wire, add fuel and oil as necessary, and start the engine.

STORAGE: (IF THE ENGINE IS TO BE UNUSED FOR 30 DAYS OR MORE)

CAUTION: NEVER STORE THE ENGINE WITH FUEL IN THE TANK INDOORS , IN ENCLOSED POORLY VENTILATED AREAS WHERE FUEL FUMES MAY REACH AN OPEN FLAME, SPARK OR PILOT LIGHT AS ON A FURNACE, WATER HEATER, CLOTHES DRYER OR OTHER GAS APPLIANCE.

Gasoline can become stale in less than 30 days and form deposits that can impede proper fuel flow and engine operation. To prevent deposits from forming, all gasoline must be removed from the fuel tank and the carburetor. An acceptable alternative to removing all gasoline is adding a fuel stabilizer to the gasoline. Fuel stabilizer (such as Tecumseh's Part No. 730245) is added to the fuel tank or storage container . Alwa ys f ollow the mix ratio f ound on the stabilizer container . Run the engine at least 10 minutes after adding the stabilizer to allow it to reach the carburetor .

CAUTION: THE USE OF SOME ANTI-ICING ADDITIVES MAY CREA TE A METHANOL FUEL BLEND. DO NOT USE ADDITIVES THA T CONT AIN METHANOL. FUEL CONDITIONERS TH AT CONT AIN ISOPROPYL ALCOHOL IS RECOMMENDED.

Draining the Fuel System:

CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS, AND AWAY FROM ANY OPEN FLAME OR COMBUSTION SOURCE. BE SURE THE ENGINE IS COOL.

1. Remove all gasoline from the fuel tank by running the engine until the engine stops, or by draining the fuel tank b y

removing the fuel line at the carburetor or fuel tank. Be careful not to damage the fuel line, fittings, or fuel tank.

2. Drain the carburetor by pressing upward on the bowl drain (if equipped) which is located on the bottom of the

carburetor bowl. On carb uretors without a bo wl drain, the carburetor may be drained by loosening the bowl nut on the bottom carburetor one full turn. Allow to completely drain and retighten the bowl nut being careful not to damage the bowl gasket when tightening.

3. If "Gasohol" has been used, complete the above procedure and then put one half pint of unleaded gasoline into

the fuel tank and repeat the above procedure. If Gasohol is allowed to remain in the fuel system during storage, the alcohol content will cause rubber gaskets and seals to deteriorate.

Change Oil: If the oil has not been changed recently, this is a good time to do it. Oil Cylinder Bore:

1. Disconnect the spark plug wire and ground the wire to the engine. Remove the spark plug and put 1/2 ounce

(14 ml) of clean engine oil into the spark plug hole.

2. Cover the spark plug hole with a shop towel.

3. Crank the engine over slowly several times.

4. Install the spark plug and connect the spark plug wire.

Clean Engine: Remove the blower housing and clean all dirt, grass or debris from the intake screen, cylinder head, cylinder cooling fins, carburetor, governor levers and linkage.

CAUTION: AVOID SPRAY FROM SPARK PLUG HOLE WHEN SLOWLY CRANKING ENGINE OVER.

CHAPTER 2 AIR CLEANERS

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GENERAL INFORMATION

The air cleaner is the device used to eliminate dust and dirt from the air supply. Filtered air is necessary to assure that abrasive particles are removed before entering the carburetor and combustion chamber . Dirt allowed into the engine will quickly wear the internal components and shorten the life of the engine.

Tecumseh engines use either a polyurethane or a papertype air filter system. A polyurethane pre-cleaner or a flocked screen may be used in conjunction with the main filter. Snow King® engines do not use an air filter.

Extremely dirty conditions may require more frequent filter cleaning or replacement.

OPERA TION

The outer cover encapsulates the air filter element(s) and prevents large particles from entering the filter box. Air is filtered through the pre-cleaner or flocked screen (if equipped) and the polyurethane or paper filter element. Precleaners or flocked screens provide additional air cleaning capacity .

In Tecumseh's Kleen Aire® system, air is drawn in through a rotating screen or recoil cover to be centrifugally cleaned by the flywheel before the air is dra wn into the air filter .

COMPONENTS

The cover holds the filter element and prevents large debris from entering the filter element.

The polyurethane wrap pre-filter is used on XL or XL/C engine models with paper filter elements.

(diag 1 & 2)

COVER

POLYURETHANE

WRAP

SEALING NUTS

PAPER

ELEMENT

AIR CLEANER

BODY

The paper or polyurethane filter element is the main filter to trap dust and dirt. Dry-type paper elements have treated paper folded for increased surface area and rubberlike sealing edges. The polyurethane filter uses an oil film to trap fine particles found in dust.

The flocked screen is used as an additional filter on XL or XL/C engine models that use a polyurethane filter element.

TROUBLESHOOTING OR TESTING

If the engine's performance is unsatisfactory (needs excessive carburetor adjustments, starts smoking abnormally , loses power), the first engine component to be checked is the air cleaner . A dirt restricted or an oil soaked element will cause noticeable performance problems. A polyurethane element may be cleaned following the service procedure listed under "Service" in this chapter. A papertype air filter should only be replaced. A paper-type element cannot have an oil film present on the paper. Follow the procedure listed in the "Service" section of this chapter for replacement. Re-try the engine after filter replacement or service. If the problem persists after filter service, see Chapter 9 under "Engine Operation Problems" for additional causes.

COVER

AIR CLEANER

BODY

FOAM

ELEMENT

FLOCKED SCREEN

SERVICE

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Service on the polyurethane element (cleaning and oiling) is recommended every three months or every twenty five operating hours, whichev er comes first. Extremely dirty or dusty conditions ma y require daily cleanings.

The paper filter element should be replaced at least once a year or more frequently if operated in dusty or dirty conditions. NOTE: NEVER RUN THE ENGINE WITHOUT THE COMPLETE AIR CLEANER ASSEMBLY INSTALLED ON THE

ENGINE. AL W A YS REPLA CE THE FIL TER ELEMENT WITH THE PROPER TECUMSEH ORIGINAL REPLACEMENT PART.

DISASSEMBLY PROCEDURE

1. Unlock the tabs or remove the screws, wingnuts or

snaps holding the air cleaner cover in place.

2. Remove the hex nuts holding the element down if

equipped. New nuts are supplied with a new filter and MUST be used for proper sealing.

3. Clean the excess contaminants out of the air cleaner

body before removing the old element.

4. Remove the old element and the polyurethane pre-

cleaner if equipped.

5. On air cleaners that use a flocked screen under the

polyurethane element, remove the air cleaner assembly from the carburetor before removing the flocked screen. This prevents dirt from entering the carburetor (diag 3).

FOAM

ELEMENT

1/2" (12.7 mm)

FOAM

WITH FLOCKED

SCREEN

ATTACHED

6. Clean the inside of the cover and body, remove the old

gasket between the carburetor and the air cleaner assembly.

7. Reinstall the air cleaner assembly using a new gasket.

8. Use the reverse procedure for reassembly. When

installing the foam polyurethane pre-cleaner , make sure the seam is installed to the outside to prevent gaps

AIR CLEANER

BODY

between the paper element and the pre-cleaner.

POLYURETHANE-TYPE FILTER ELEMENT

This type of air filter can be serviced when restricted with dust or dirt. Wash the filter or pre-cleaner in a liquid detergent and water solution until all the dirt is removed. Rinse in clear water to remove the detergent solution. Squeeze the element (do not twist) to remove the e xcess water . Wrap the element in a clean cloth and squeez e it (do not twist) until completely dry .

Re-oil the element by applying engine oil and squeezing it vigorously to distribute the oil. Roll the element in a cloth and squeeze it (do not twist) to remove the excess oil.

Clean the air cleaner housing and cover being careful not to allow dirt to fall into the carburetor or intak e pipe.

PAPER -TYPE FILTER ELEMENT

Paper type air filter elements can only be serviced by replacement. Do not attempt to clean a paper filter element.

CHAPTER 3 CARBURETORS AND FUEL SYSTEMS

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GENERAL INFORMATION

Tecumseh uses two basic types of carburetors, float and diaphragm type carburetors. Float type carburetors use a hollow float to maintain the operating lev el of fuel in the carburetor. Diaphragm type carburetors use a rubber-like diaphragm. One side is exposed to intake manif old pressure and the other side to atmospheric pressure. The diaphragm provides the same basic function (maintaining the proper fuel level in the carburetor) as the float.

An advantage of the diaphragm carburetor over the float style is that the diaphragm carburetor will allow the engine to operate at a greater degree of tiltability.

T ecumseh carburetors are identified b y a manufacturing number and date code stamped on the carb uretor as illustrated (diag. 1).

When servicing carburetors, use the engine model and specification number to obtain the correct carburetor part number. An alternate method to finding the correct carburetor part number is to use the manufacturing number

ALTERNATE LOCATION

FOR MANUFACTURING

NUMBER

89 4F5

and date code stamped on the carburetor and convert this number to a part number. In the carburetor section of the Master Parts Manual or Microfiche Catalog or computer parts look-up system. A cross reference chart will conv ert a carburetor manufacturing number to a Tecumseh part number.

89 4F5

Complete carburetor replacement may be accomplished with a standard service carburetor. A standard ser vice carburetor is a basic carburetor that may require the use of original carburetor parts or additional new parts to adapt to the specification. An instruction sheet is provided with the new service carburetor or see “SER VICE” in this chapter .

MANUFACTURING

NUMBER

CARBURETOR

DATE CODE

CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS, AND AWAY FROM ANY OPEN FLAME OR COMBUSTION SOURCE. BE SURE THE ENGINE IS COOL.

NOTE: Todays fuels can cause many problems in an engines performance, due to the fuels quality and short shelf life.

Always check fuel as a primary cause of engine performance.

1. Remove the air filter , heater box, or air cleaner assembly if applicable to visually check that the choke shutter completely closes or check to see if fuel comes out of the main nozzle during priming.

2. If the fuel flow from the tank is adequate and no fuel is evident during priming, the carburetor will need to be removed f or service. See “Service” in this chapter or consult the “Carburetion Troubleshooting” chart to diagnose carburetor symptoms. Improper fuel flow indicates the fuel, fuel line, filter or tank require cleaning or replacement.

3. Check the engine compression using a commercially available compression tester and follow the tester’s recommended procedure. Lo w compression, a dry spark plug, adequate fuel flow, and a kno wn good functional carburetor indicates an internal engine problem exists. See under “Troubleshooting.”

4 . A wet spark plug indicates fuel is being supplied by the carburetor . The engine may be flooded by a restricted

air filter, carbon shorted or defective spark plug, excessive choking or over priming, improperly adjusted or defective carb uretor . With the spark plug removed and a shop towel o ver the spark plug hole, turn the engine over slowly 3 or 4 times to remove excess gasoline from the engine cylinder.

CAUTION: KEEP ALL COMBUSTIVE SOURCES AWAY. AVOID THE SPRAY FROM THE SPARK PLUG HOLE WHEN CRANKING THE ENGINE O VER.

5 . Replace the air filter if restricted or oil soaked. Replace the spark plug if questionable. Install the spark plug and

high tension lead and try to start the engine.

6. If the engine floods and fails to start, the carburetor will require service. See the proceeding “Carburetion T roubleshooting” chart for additional causes. If the carburetor is functioning properly the problem ma y be ignition timing related. See “T roub leshooting" under "Ignition”.

OPERATION

Main Menu

In the “CHOKE” or “START” position, the choke shutter is closed and the only air entering the engine enters through openings around the shutter. As the engine starts to rotate, downw ard piston trav el creates a lo w air pressure area (or vacuum) above the piston. Higher pressure (atmospheric) air rushes into the engine and fills this low pressure area. Since the majority of the air passage is blocked by the choke shutter, a relatively small quantity of air enters the carburetor at an increased speed. The main nozzle and both idle fuel discharge ports are supplying fuel due to the low air pressure in the engine intake. Maximum fuel flow through the carburetor orifices combined with the reduced quantity of air that passes through the carburetor , make a v ery rich fuel mixture which is needed to start a cold engine.

At engine IDLE speed, a relatively small amount of fuel is required to operate the engine. The throttle is almost completely closed. Fuel is supplied through the primary idle-fuel discharge orifice.

NOTE: Dual system carburetors do not have an idle circuit.

During INTERMEDIATE engine operation, a second orifice is uncovered as the throttle shutter opens, and more fuel is allowed to mix with the air flowing into the engine.

During HIGH SPEED engine operation, the throttle shutter is fully opened. Air flows through the carburetor at high speed. The venturi, which decreases the size of the air passage through the carburetor, further accelerates the air flow. This high speed movement of the air decreases the air pressure at the main nozzle opening. Fuel is forced out the main nozzle opening due to the difference in the air pressure on the fuel in the carburetor bowl and the reduced air pressure at the main nozzle opening.

For the fuel to flow, the carburetor bowl must be either vented externally or internally . Some internally vented float style carburetors use a tygon tube and a vent within the air intake. This tube m ust be present for the carb uretor to operate properly (diag. 2).

Air is bled into the main nozzle and through the air bleed located in the air horn. This mix es the fuel and air prior to the fuel leaving the main nozzle. Atomization occurs as the fuel mixture contacts the fast moving air stream. This mist then flows into the intake of the engine.

FUEL PRIMERS

Primers may be mounted remotely or as an integral part of the carburetor. The basic function of the primer is to supply a charge of air to the carburetor main well, or carburetor bowl. On diaphragm carburetors it displaces fuel directly into the carburetor venturi. This displaced fuel provides a rich mixture necessary for engines to start easily on the first or second attempt (diag. 3 & 4).

Primers must be vented either internally (a passage in the carburetor air horn prior to the venturi) or externally (through a hole in the primer bulb). The vent allows air to fill the primer bulb after the primer bulb is released. On diaphragm carburetors a one way valve in the body prevents the fuel from being forced back into the fuel tank.

Two different methods are used to prime float style carburetors, leg prime and bowl prime. The leg prime system is used only on the dual system carburetor . Air is forced into the center leg of the carburetor, which then forces an enriched mixture of fuel up the main nozzle. The bowl prime method is used on Series 6, 8, 9 and 10 carburetors and is distinguished by a stepped or hour glass shaped primer bulb. A good seal of the primer bulbs center lip is critical to assure that a full charge of air reaches the bowl. Also critical is a tight seal around the float bowl.

TYGON TUBE

LOCATION

BOWL PRIME

PRIMER BULB

MAIN NOZZLE

EMULSION

TUBE

MAIN JET

NOTE: Never re-use a bowl gasket.

IMPULSE FUEL PUMPS

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Impulse fuel pumps may either be mounted externally onto the carburetor fuel inlet or remotely mounted. These pumps are connected in the fuel line between the fuel supply and the carburetor or directly to the fuel inlet.

Impulse fuel pumps are operated by crankcase impulses created by the up and down movement of the piston. A hose called a pulse line connects the fuel pump diaphragm chamber to the crankcase and transmits these impulses to the pump diaphragm. The impulses actuate the diaphragm and flap valves to lift the fuel from the fuel tank to the carburetor (diag. 6).

FLOAT STYLE CARBURETORS

A float is used to maintain the operating volume of fuel in the carburetor bowl. As the fuel is used by the engine, the fuel volume in the carburetor bowl drops and the float moves downward. This allows the inlet needle valve to move off the sealing seat. Fuel flows by gravity or a pulse pump into the fuel bowl. As the fuel volume in the bowl again rises, it raises the float. This upward float motion moves the inlet needle valve to the closed position. When the needle contacts the seat, the fuel flow is stopped. The tapered end of the inlet needle varies the fuel flow rate so that the fuel volume in the carburetor bowl will remain constant (diag. 7). The float height is set according to the service procedure.

DIAPHRAGM (PRESSURE DIFFERENTIAL) CARBURETORS

This type of carburetor uses a rubber-like diaphragm which is exposed to intake manifold pressure on one side and to atmospheric pressure on the other. T ecumseh diaphragm carburetors use the diaphragm as a metering device. As the intake manifold pressure decreases due to downward piston travel, the atmospheric pressure on the vented side of the diaphragm moves the diaphragm against the inlet needle. The diaphr agm mov ement ov ercomes the spring tension on the inlet needle and moves the inlet needle off the seat. This per mits the fuel to flow through the inlet valve to maintain the correct fuel volume in the fuel chamber. The inlet needle return spring closes the inlet valve when the pressure on the diaphragm equalizes or a pressure higher than atmospheric exists on the intake side (upward piston travel). The diaphragm meters a correct fuel volume in the fuel chamber to be delivered to the mixing passages and discharge ports (diag. 8).

IDLE AND

PROGRESSION

HOLES

THROTTLE

SHUTTER

IDLE

ADJUSTMENT

MAIN NOZZLE

EMULSION

TUBE

THROTTLE

SHUTTER

IDLE

ADJUSTMENT

IDLE AIR

BLEED

MAIN

ADJUSTMENT

CHECK BALL

MAIN AIR

BLEED

CHOKE

SHUTTER

INLET NEEDLE

AND SEAT

FLOAT

CHOKE

SHUTTER

NEEDLE AND

SEAT ASSEMBLY

A main or idle adjustment needle may be replaced by an internally fixed jet on some models.

The main nozzle contains a ball check valve. The main purpose of this ball check is to eliminate air being drawn down the main nozzle during idle speeds and leaning the idle mixture.

An advantage of the diaphragm carburetor over the float system is that the diaphragm carburetor increases the angle that the engine may be operated at.

MAIN

ADJUSTMENT

DIAPHRAGM

COMPONENTS

Main Menu

Loosen screw until it just clears throttle lever, then turn screw in 1 turn.

Place detent reference mark to proper location.

Check spring for return action and binding.

Remove welch plug and blow air through air passages.

Remove adjustment screw. To adjust 20° slant engines, the engine must be mounted in its normal 20° slant position.

Check ball is not serviceable on some models.

Blow air through passage.

Check shaft for looseness or binding. Shutter must be positioned with detent reference marks on top parallel with shaft and to the right or 3 o'clock position.

Check spring for return action and binding.

Remove idle adjustment screw. Check needle tip and condition of "O" ring. Remove welch plug and blow out all passages.

NOTE: On models which have metering rods, do not install idle adjustment screw with carburetors upside down, as pin will obstruct movement of adjustment screw causing damage

*NON METALLIC ITEMS - CAN BE DAMAGED BY HARSH CARBURETOR CLEANERS

IDLE SPEED ADJUSTMENT SCREW

THROTTLE SHAFT AND LEVER DETENT REFERENCE MARK

ON THROTTLE SHUTTER THROTTLE SHUTTER

THROTTLE SHAFT RETURN SPRING

IDLE PROGRESSION HOLE

IDLE AIR BLEED

*IDLE MIXTURE ADJUSTMENT SCREW AND "O" RING (If Present)

*MAIN MIXTURE ADJUSTMENT SCREW AND "O" RING (If Present)

WELCH PLUG (If Present) *MAIN NOZZLE CHECK BALL (If Present)

*NON METALLIC ITEMS - CAN BE DAMAGED BY HARSH CARBURETOR CLEANERS

IDLE AND INTERMEDIA TE AIR BLEED

THROTTLE SHAFT AND LEVER THROTTLE SHUTTER DETENT

REFERENCE MARK

THROTTLE SHAFT RETURN SPRING

IDLE AND INTERMEDIA TE ORIFICES

IDLE AND INTERMEDIA TE FUEL CHAMBER (COVERED WITH WELCH PLUG)

IDLE AND INTERMEDIA TE FUEL MIXTURE PASSAGE

*IDLE ADJUSTMENT SCREW AND "O" RING

ATMOSPHERIC VENT

SOFT BAFFLE PLUG

IDLE AND INTERMEDIA TE FUEL TRANSFER PASSAGE

METERING ROD OR PIN IN FUEL TRANSFER PASSAGE

BALL PLUG CUP PLUG IDLE AND INTERMEDIA TE

FUEL TRANSFER PASSAGE IDLE AND MAIN FUEL PICK UP ORFICE

IDLE

(DO NOT REMOVE)

CHOKE SHAFT AND LEVER

CHOKE SHUTTER

MAIN NOZZLE

*INLET FITTING SCREEN

*INLET FITTING

*INLET SEAT GASKET

*INLET NEEDLE SEA T AND SPRING ASSEMBLY

*DIAPHRAGM GASKET *DIAPHRAGM

ATMOSPHERIC VENT HOLE

IDLE SPEED ADJUSTMENT

MAIN NOZZLE (EMULSION TUBE)

CHOKE SHAFT AND LEVER

CHOKE PLATE

HIGH SPEED AIR BLEED

INLET FITTING

*INLET NEEDLE AND SEAT

*FLOAT BOWL

GASKET FLOAT SHAFT

NUT AND MAIN ADJUSTMENT SEA T *MAIN ADJUSTMENT SCREW AND "O" RING SEAL

INLET NEEDLE CLIP (If Present)

IDLE FUEL TRANSFER PASSAGE AND ANNULAR GROOVE

FLOAT FLOAT BOWL *GASKET

Check shaft for binding. Position shutter opening towards inlet fitting side or air horn.

Blow air through passage.

Part of inlet fitting. If fuel is restricted, clean or replace fitting.

Bulb primer models have Viton* one way valve, in or behind fitting.

Remove and replace.

Proper installation of assembly is important.

Gasket and diaphragm sequence may be reversed on some models. Head of rivet must touch inlet needle. Rivet is hooked into inlet needle control lever on some models.

Hole must be clean. On models with bulb primer, vent hole is very small and is located off center.

Loosen screw until it just clears throttle lever, then turn screw in one turn.

Removable on emission carbs. nonmetallic only .

Check shaft for binding position opening to bottom of air horn.

Blow air through passage. Do not remove restrictor if present.

Proper installation is important.

Replace.

Must hook over float tab.

Check float for leaks or dents. Clean bowl and adjust float level position gasket or gaskets.

If the carburetor is used on a 20° slant engine, the engine must be in its normal 20° slanted position for adjustment.

Check needle for damage and "O" ring for cracks. Clean all passages in nut with compressed air.

CARBURETOR IDENTIFICATION

Main Menu

Tecumseh has a variety of carburetors. To help identify these carburetors here are some simple procedures to follow.

DUAL SYSTEM CARBURETORS

The easiest way to identify the dual system carburetor is by the presence of a large primer bulb located on the side of the carburetor. The absence of adjustment needles help to identify the carb as well. The dual system carburetor is used on 4-cycle vertical crankshaft rotary mower engines. (diag. 11).

SERIES 1 CARBURETORS

Series 1 carburetors come in a variety of styles. They are used on both 2 and 4 cycle vertical and horizontal shaft engines in the 2 through 7 h.p. range. It is a float style carburetor with a smaller venturi than the Series 3 and 4 carburetors. Some will have an adjustable idle and main and others will have a fixed main with an adjustable idle. There are also some fixed speed applications that will only have a fixed main system and the idle system will not be drilled. (diag. 12).

NOTE: Emissionized carburetors will have a fixed jet.

SERIES 3 & SERIES 4 CARBURETORS

Series 3 and 4 carburetors are generally used on 8 through

12.5 horsepower 4-cycle engines. The v enturi size of these carburetors are larger than Series 1 and Dual System Carburetors. The quic kest wa y to identify these carburetors is by the presence of bosses on each side of the idle mixture screw. To identify the Series 3 from a Series 4, view the carburetor from the throttle end. The Series 3 has (1) screw securing the throttle plate and the Series 4 uses (2) screws. (diag. 13 - 15)

DIAPHRAGM CARBURETORS

The diaphragm carburetors are unique. These carburetors can be operated at a more severe angle than float style carburetors. The y still require that the fuel supply be located in a position that allows it to be gravity fed. Its most distinctive feature is the lack of a fuel bowl. (diag. 16).

BOSSES

SERIES 3

SERIES 4

NOTE: Emissionized carburetors will have a fixed jet.

SERIES 6 CARBURETORS 4-CYCLE

Main Menu

Series 6 carburetors are used on 2 and 4-cycle engines. They have a larger venturi than the dual system carburetor and use a simple fixed idle system. Series 6 carburetors used on both vertical and horizontal applications are nonadjustable. The 4 cycle v ersion pictured has a stepped primer bulb. (diag. 17).

SERIES 8

The Series 8 carburetor has both a fixed main and idle circuit. The fixed idle system uses a restricted jet that meters the fuel. The idle restrictor jet will be capped to prevent access unless remo ved. The fix ed main jet is part of the bowl nut. A ball plug is visible from the bottom, which seals the metering passage. This carburetor also has a serviceable main nozzle emulsion tube. It also has a stepped primer bulb to assist in starting. (diag. 18)

CAPPED FIXED

JET

SERIES 9

The Series 9 carburetor uses the same body as the Series 8 but has a simple fixed idle system, identical to the one used on the Series 6 carburetor. It has the idle discharge port located at the 7 o'clock position on the throttle end of the carburetor . Identify this carburetor b y the stepped primer bulb, the presence of a non-drilled idle mixing well and a serviceable main nozzle emulsion tube. (diag. 19)

SERIES 10 (EMISSION)

The Series 10 carburetor is identical to the Series 8 carburetor with the addition of a choke to assist in cold weather starts. It also has a fix ed idle and main. The idle restrictor jet will be capped to prevent access unless the cap is removed. The fixed main jet is part of the bowl nut. A ball plug is visible from the bottom, which seals the metering passage. This carburetor also has a serviceable main nozzle emulsion tube and a stepped primer bulb to assist in starting. (diag. 20)

MIXING WELL

CAST BUT NOT

MACHINED

IDLE JET

CAST BUT NOT

MACHINED

NON-TECUMSEH CARBURETORS DELLORTO CARBURETOR

The Dellorto carburetor is similar to the dual system carburetor . It has no adjustments and has a primer assist start. It has a noncorrosive float and the needle is viton tipped, eliminating the viton seat found in the dual system carburetor. The angle of the fuel inlet is adjustable and attached to the carburetor body with a banjo bolt. This carburetor is used on some TVS rotary lawnmow er engines.

ENGINE

Main Menu

TROUBLESHOOTING

Engine Will Not Start

Check For Spark

Wet Check If Spark Plug Is Wet or Dry Dry

Defective Spark Plug Check Fuel Supply and Fuel

Cap Vent

Restricted Air Filter Restriction in Fuel System

(filter, screen)

Improper or Stale Fuel Carburetion Problem

Sheared or Partially Sheared Poor Compression

Flywheel Key

Carburetion Problems Due to

Flooding, Over Priming, etc.

Ignition System

AIR SYSTEM

Main Menu

PROBLEMS

CARBURETION

TROUBLESHOOTING

START IDLE ACCELERATE HIGH SPEED

Will

Not

Run at

High

Speed

Low

Power

Hunts at

High

Speed

Runs with

Needle

Closed

Hard

Starting

Fuel Leak

Carburetor

Engine

Floods

Will Not

Idle

Rich Idle

Idles with

Needle

Closed

Hunts -

Erratic

Idle

Idles

Fast -

Lean

Will Not

Acceler-

ate

Over Rich

Accelera-

tion

Hesitates

Engine

Over-

speeds

Plugged Air Filter

Leaky Carburetor

Gasket

Throttle or Choke

Shafts Worn

Choke Not

Functioning

Properly

Plugged

Atmospheric Vent

Air Bleed

Restricted

Damaged or

Leaky "O" Rings

DIAPHRAGM

SYSTEM

PROBLEM

Damaged

Diaphragm

Stuck or Dirty Ball

Check

Diaphragm

Upside Down

ÁÁ

ÁÁ Á Á

ÁÁ

ÁÁÁÁ

ÁÁ

FUEL SYSTEM

PROBLEM

Plugged Tank

Filter or Vent

Fuel Pick-up

Incorrect Float

Main Nozzle

Needle and Seat

Fuel Inlet Plugged

Restricted

Idle Port

Restricted

Damaged

Adjustment

Needles

Height

Restricted

Dirty, Stuck

ÁÁ

ÁÁÁ

ÁÁ

TESTING

Main Menu

1. After repeated efforts to start the engine using the procedure listed in the operator’s manual fail, check for spark by removing the high tension lead and the spark plug. Install a commercially av ailable spark plug tester and check for spark. If spark is evident and acceptable , proceed to step 2. If no or weak spark, see Chapter 8 under "Testing".

2. Visually inspect the spark plug for a wet condition indicating the presence of gasoline in the cylinder.

3. If the spark plug is dry, check for restrictions in the fuel system before the carburetor. If the spar k plug is wet, continue with step # 7. Chec k to see if the fuel cap vent is open. With a proper draining receptacle, remove the fuel line clamp on the carburetor fuel inlet and pull the fuel line off the fitting to examine the fuel flow and fuel condition.

4. Remove the air cleaner element or air cleaner assembly to visually check that the choke shutter completely closes or check to see if fuel comes out from the main nozzle during priming.

5. If the fuel flow is adequate and no fuel is evident during priming, the carburetor will need to be removed for service. See “Service” in this chapter or consult the “Carburetion T roubleshooting” chart if other problems exist. Improper fuel flow indicates the fuel, fuel line, filter or tank require cleaning or replacement.

6. Check the engine compression using a commercially availab le compression tester and follow the tester’ s recommended procedure. Low compression, a dry spark plug, adequate fuel flow, and a known good functional carburetor indicates an internal engine problem exists. See Chapter 9 under “Engine Operation Prob lems. ”

7. A wet spark plug indicates fuel is being supplied by the carburetor. The engine may be flooded by a restricted air filter, carbon shorted or defective spark plug, e xcessiv e choking or o v er priming, improperly adjusted or defectiv e carburetor, or the wrong ignition timing. With the spark plug removed and a shop towel ov er the spark plug hole, turn the engine over slowly 3 or 4 times to remo ve e xcess gasoline from the engine cylinder.

CAUTION: KEEP ALL COMBUSTIVE SOURCES AWAY. AVOID THE SPRAY FROM THE SPARK PLUG HOLE WHEN CRANKING THE ENGINE O VER.

8. Replace the air filter if restricted or oil soaked. Replace the spark plug if questionable. Install the spark plug and high tension lead and retry starting the engine.

9. If the engine floods and fails to start, the carburetor may require service. See the preceding “Carburetion T roub leshooting” chart for additional causes. If the carb uretor is functioning properly the problem may be ignition timing related. See Chapter 8 under “Ignition T roub leshooting. ”

SER VICE

CARBURETOR PRE-SETS AND ADJUSTMENT

NOTE: EMISSION GRADE CARBURETORS HA VE FIXED IDLE AND MAIN JETS. THE ABSENCE OF THE ADJUSTING SCREW INDICATES A FIXED JET OR RESTRICTOR AND NO ADJUSTMENT IS NECESSARY. THE IDLE RESTRICTOR ON THE SERIES 8 CARBURETOR APPEARS AS AN ADJUSTABLE SCREW. THIS IS NOT ADJUST ABLE AND MUST REMAIN TIGHT FOR PROPER OPERATION.

Before adjusting any mixture screws the necessary carburetor presets should be made. Check for the proper governor adjustments as outlined in Chapter 4. Identify the correct carburetor model and manufacturer to find locations of the high and low speed adjustment screws. Check the throttle control bracket for proper adjustment allowing a full choke shutter position. See Chapter 4 under "Speed Controls and Linkage". Check to see if the normal maintenance procedures have been performed (oil changed, fresh fuel, air filter replaced or clean). Consult microfiche card #30 to find the correct R.P.M. settings for the engine, or consult Service Bulletin #107 for the revised safety specification for rotary type power lawn mowers. Start the engine and allow it to warm to operating temperature. The carburetor can now be adjusted.

PRE-SETS AND ADJUSTMENTS

Main Menu

(TECUMSEH AND WALBRO CARBURETORS)

NOTE: OVERTIGHTENING WILL DAMA GE THE T APER

PORTION OF THE NEEDLE. All adjustments should be made with the carburetor in the operating position.

Turn both the main and idle mixture adjusting screws in (clockwise) until finger tight.

Now back the mixture screws out (counterclockwise) to

Engine Model

All models with float-type

carburetors All models with diaphragm-type carburetors

Carburetor Model Number

LMH WHG & LME LMK

Tecumseh Carb uretors

Main Pre-set

1-1/2 turn 1 turn

1 turn 1 turn

Walbro Carburetors

1-1/2 turn

1-1/4 turn

Fixed

Idle Pre-set

1-1/2 turn

1-1/4 turn

1 turn

obtain the pre-set figure in the chart shown at right.

FINAL ADJUSTMENTS (NON EMISSION ENGINES)

Start the engine and allow it to warm up to normal operating temper ature (3 - 5 minutes). Set the speed control to the HIGH or F AST position. From the recommended preset position, turn the main mixture adjustment screw in (clockwise) slowly until the engine begins to run erratic (lean). Note the position of the screw . Now , turn the screw out (counterclockwise) until the engine begins to run erratic (rich). Turn the screw in (clockwise) midway between these tw o positions. This will be the best setting. (diag. 21, 22 & 23).

Set the speed control to the IDLE or SLOW position. Adjust the idle mixture screw following the same procedure used to adjust the main mixture adjustment screw .

TECUMSEH CARBURETORS

DIAPHRAGM

IDLE MIXTURE

SCREW

SERIES 1

MAIN MIXTURE

SCREW

IDLE MIXTURE

SCREW

SERIES 3 & 4

MAIN MIXTURE

SCREW

IDLE MIXTURE

SCREW

MAIN MIXTURE

SCREW

If further adjustment is required, the main adjustment should be made under a loaded condition. If the engine stops or hesitates while engaging the load (lean), turn the main mixture adjusting screw out

(counterclockwise) 1/8 turn at a time, testing each setting with the equipment under load, until this condition is corrected.

If the engine smokes excessively (rich), turn the main adjusting screw in (clockwise) 1/8 turn at a time, testing each setting with the equipment under load, until this condition is corrected.

After the main mixture screw is set, move the speed control to the IDLE or SLOW position. If the engine does not idle smoothly , turn the idle mixture screw 1/8 turn either in (clockwise) or out (counterclockwise) until engine idles smoothly.

Recheck the high and low R.P.M. setting and adjust as necessary.

NON-ADJUST ABLE CARB URET ORS

DUAL SYSTEM AND SERIES 6

SERIES 8

MIXING WELL

CAST BUT

NOT

MACHINED

SERIES 9

SERIES 10

CHOKE

NON-ADJUSTABLE

PRIMER NO CHOKE

CAPPED FIXED

JET

CAST BUT NOT MACHINED

IDLE JET

CAPPED IDLE

RESTRICTOR

DISASSEMBLY PROCEDURE

Main Menu

NOTE: Engines which are identified as compliant with CARB (California Air Resources Board) or EPA (US Environmental Pr otection Agency) regulations can NOT be changed from the factory unless specifically authorized.

FLOAT STYLE CARBURETORS

1. Note or mark the high and low mixture adjusting screws to aid in reassembly (if applicable). Remove the high speed adjusting screw, bowl nut, and float bowl. Remove the idle mixture screw assembly.

2. Note the position of the spring clip on the inlet needle and float, the long end of the clip must face toward the choke end of the carburetor. Remove the float hinge pin with a needlenose pliers. Some carburetors use a float dampening spring to aid the inlet valve in maintaining a steady position during rough service applications. Note the position of the hooks before removing the float hinge pin (diag. 28).

3. Remove the float, clip, and inlet needle.

4. Remove the inlet needle seat using a #4 crochet hook, a wire or paper clip with a 3/32" (2.38 mm) hook end as shown. Push the hook through the hole in the center of the seat to remove it. (diag. 29).

LONG END

OF CLIP

CHOKE

END

3/32" (2.38 mm)

HOOK END

CLIP

OPEN END

OF CLIP

THROTTLE

END

5. Note or mark the action of the choke and throttle shutters, and/or the hook points of the choke or throttle return spring, or seal retainer springs located on the top of the choke and/or throttle shaft. Remove the throttle shutter, throttle shaft, choke shutter, springs and choke shaft by removing the screw(s) that attach the throttle or choke shutter to the shaft inside the air horn.

6. Remove the primer bulb (if equipped) by grasping it with a pliers and pulling and twisting out of the body. Remove the retainer by prying and lifting it out with a screwdriver . Do not re-use the old bulb or retainer (diag.

30).

7. Some Tecumseh float style carburetors have a damper spring which is installed as shown. (diag. 31)

POINTS TOWARD

THE CHOKE END

8. Remove all welch plugs if cleaning the carburetor.

Main Menu

Secure the carburetor in a vise equipped with protective jaws. Use a small chisel sharpened to a 1/8" (3.175 mm) wide wedge point. Drive the chisel into the plug to pierce the metal, then push down on the chisel to pry the plug out of the hole (diag. 32).

NOTE: DO NOT REMOVE ANY BALL OR CUP PLUGS (diag. 33).

9. Note the direction of the inlet fitting. If necessary the inlet fitting can be removed. (See page 24).

10. The main nozzle on Series 8 and Series 9 carburetors can be removed by pressing the tube outward from the venturi thru the center leg. This nozzle is nonmetallic and has an "O" ring seal on the top and bottom end of the tube. Do not remove a main nozzle that is made of brass from any Tecumseh carburetor. These are pressed in at the factory to a specific depth. When removing the nozzle, the top "O" ring may not come out with the tube. The "O" ring must be remo v ed and placed on the nozzle before it is placed back into the center leg or it will not seal properly . (diag. 34)

SMALL CHISEL

PRY OUT

PLUG

DO NOT ALLOW

CHISEL POINT

TO STRIKE

CARBURETOR

BODY OR

CHANNEL

REDUCER

BALL PLUG

PIERCE PLUG WITH TIP

SMALL CHISEL

DO NOT REMOVE PLUGS

BRASS OR BALL PLUG

WELCH PLUG TO BE

REMOVED

ABOUT 1/8"

(3.175 mm)

WIDE

The main nozzle on some Walbro carburetors are removable for service. If you remove it, a service nozzle with the under cut fuel passage must be installed or problems will occur (diag. 35).

IDLE FUEL PASSAGE

REDUCTION ROD INSIDE

NOT USED ON SERIES 7

OR VECTOR CARBS.

"O" RING

ON TOP OF STEP

(IN GROOVE)

"O" RING IN GROOVE

"O" RING

SERVICE MAIN NOZZLE

REUSABLE

UNDERCUT

ANNULAR

GROVE

ORIGINAL MAIN NOZZLE

DO NOT REUSE

Diaphragm Carburetors

Main Menu

1. Remove the screws holding the diaphragm cover on.

2. Remove the cover, gask ets, and diaphr agm noting or marking the sequence or location to aid in reassembly .

NOTE: If a "F" designation on the choke end of the carburetor is present, place the diaphragm on first, then the gasket and cover. If no "F" is present, the gasket goes first.

3. Note or mark the high and low mixture adjustment screws. Remove the screw assemblies.

4. Note or mark the action of the choke and throttle shutters and the hook points of the choke or throttle return spring or seal retainer springs located on the top of the choke or throttle shaft. Remove the throttle shutter, throttle shaft, choke shutter , springs and choke shaft by removing the screw or screws that attach the throttle or choke shutter to the shaft inside the air horn.

5. Use a 9/32" (7.144 mm) thin wall socket to unscrew and remove the inlet needle and seat assembly (diag.

36).

6. Note and mark the direction of the inlet fitting. If necessary the inlet fitting can be removed by pulling with a pliers or vise. Some diaphragm carburetors have a strainer as an integral part of the fuel fitting. If the strainer is lacquered or cannot be cleaned, the fitting must be replaced.

7. Remove all welch plugs if cleaning the carburetor. Secure the carburetor in a vise equipped with protective jaws. Use a small chisel sharpened to a 1/8" (3.175 mm) wide wedge point. Drive the chisel into the plug to pierce the metal, then push down on the chisel to pry the plug out of the hole.

NOTE: DO NO T REMOVE ANY BALL OR CUP PLUGS.

"F" DESIGNATION

"F"

DIAPHRAGM FIRST NOT GASKET

To ser vice, disassemble the pump by removing the four (4) screws. Clean all parts with a solvent and install a new kit which consists of a coil spring, gaskets and diaphragms (diag. 37 & 38).

All Tecumseh carburetors with an adjustable float require the correct float height to achieve the proper operation and easy engine starts. T o chec k the float height, hold the carburetor in an upside down position. Remove the bowl nut, float bowl, and "O" ring. Place an 11/64" (4.36 mm) diameter drill bit across the top of the carburetor casting on the opposite side and parallel to the float hinge pin (diag. 39). The float must just touch the drill bit when the bit is flush with the edge of the float. If the float is too high or too low, adjust the height by bending the tab accordingly. If the required adjustment is minor, the tab adjustment may be made without removing the float and carefully inserting a small bladed screwdriver to bend the tab.

Float sticking can occur due to deposits or when the fuel tank is filled for the first time, this condition can be quickly corrected by loosening the carburetor bowl nut one full turn. Turn the bowl 1/4 turn in either direction, then return the bowl to its original position and tighten the bowl nut.

IMPULSE FUEL PUMP

FLOAT ADJUSTING PROCEDURE

OLD STYLE

11/64" (4.36 mm)

DRILL BIT

NEW STYLE

RIM

INSPECTION

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After careful disassembly of the carburetor and the remov al of all non metallic parts, the carburetor body and all other metallic parts should be cleaned with solvent, or commercial carburetor cleaner, no longer than 30 minutes . Use compressed air and soft tag wire to clean internal carburetor passages. To do a proper cleaning job, the welch plugs must be removed to expose the drilled passages.

NOTE: The nylon check balls used in some diaphragm carburetors are not serviceable. Nylon can be damaged if subjected to harsh cleaners for prolonged periods.

Throttle and Choke

Examine the throttle lever and shaft, choke lever and shaft, and carburetor body at the bearing points and holes into which the linkage is fastened, and replace if worn or damaged. Any looseness in these areas can cause dirt to enter the engine and cause premature wear. If dust seals are present, these should be positioned ne xt to the carburetor body.

Idle and High Speed Mixture Adjusting Screw

RETAINER NUT

Examine the idle mixture needle tip and tapered surface for damage. The tip and tapered surf ace of the needle must not show any wear or damage at all. If either is worn or damaged, replace the adjusting needle. Tension is maintained on the screw with a coil spring. Examine and replace the “O” ring seal if damaged (diag. 40).

Examine the tapered surface of the high speed mixture needle. If the tapered surface is damaged or shows wear , replace the needle (non-emissioned). Some Tecumseh carburetors use serviceable jet main nozzles. These are identified as being non-metallic.

FUEL-

Fuel Bowl Retaining Nut

METERING

PORT

ONE-HOLE TYPE

The retaining nut contains the transfer passage or metering jet through which fuel is delivered to the high speed and idle circuit of the carburetor. If a problem occurs with the

idle circuit, examine the small fuel passage in the annular groove in the retaining (metering) nut. This passage must be clean for the proper transf er of fuel into the idle metering circuit. Torque retaining nut to 50 in. lbs. (5.65 Nm) when reinstalling.

"O" RING

BRASS WASHER (used to protect the

"O" ring from the spring)

SPRING

HIGH SPEED

ADJUSTMENT SCREW

IDLE FUEL

TRANSFER

PASSAGE

TW0-HOLE TYPE

FUEL-INLET

PORTS

There are two different types of bowl nuts that are used on adjustable main, float style carburetors. One type has one fuel metering port at the bottom of the nut, and the other has two fuel inlet por ts at the bottom of the nut. This difference relates to calibration changes to the carburetor and is dependent on the application (diag. 41).

NOTE: DO NO T INTERCHANGE BOWL NUTS. The fuel inlet ports must be free of any debris to allow proper fuel flow .

Fuel Bowl, Float, Needle and Seat

The float bowl must be free of dirt and corrosion. Clean with solvent or carb uretor cleaner . Examine the float for damage. Check the float hinge bearing surf aces for wear , as well as the tab that contacts the inlet

needle. Replace an y damaged or worn parts. The needle and seat should be replaced if any fuel delivery problems are experienced (flooding or starvation). Sealing

problems with the inlet needle seat may not be visible, so replacement is recommended.

Diaphragms, Pulse Pumps, and Primer Bulbs

Inspect diaphragms, gaskets, and primer bulbs for cracks, tears, hardness or brittleness. Replace if necessary. 20

ASSEMBLY

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Welch Plugs

To install a new welch plug after cleaning the carburetor, secure the carburetor in a vise equipped with protective jaws. Place the welch plug into the receptacle with the raised portion up. With a punch equal to, or greater than the size of the plug, merely flatten the plug. Do not dent or drive the center of the plug below the top surface of the carburetor. After installation of the welch plug, seal the outer diameter with finger nail polish or equivalent (diag.

42).

Throttle Shaft and Plate

When reassembling, it is important that the lines or lettering on the throttle plate are facing out when in the closed position. Position throttle plate with two lines at 12 and 3 o’clock. If the throttle plate has only one line, the line should be positioned in the 12 o’clock position on Series 1, 6, 8, and 9 carburetors, and positioned in the 3 o’clock position on Series 3 and 4 carburetors (diag. 43 & 44).

Test the operation of the throttle and return spring (if equipped). If binding occurs, correct by loosening screws and repositioning throttle plate.

NEW WELCH PLUG

THROTTLE

PLATE

SERIES 1, 6, 8, 9, 10

SERIES 3 AND 4

FLAT END PUNCH

SAME OR LARGER

DIAMETER OF

PLUG

THROTTLE LEVER

TWELVE O'CLOCK

POSITION

THREE O'CLOCK

POSITION

Always use a new screw(s) when reinstalling the throttle shutter (Tecumseh screws are treated with dry-type adhesive to secure them in place).

NOTE: NEVER REUSE OLD SCREWS.

Choke Shaft and Plate

The choke plate is inserted into the air horn of the carburetor in such a position that the flat surface of the choke is down. Choke plates will operate in either direction. Make sure it is assembled properly for the engine. Test the operation of the choke and return spring function if equipped (diag. 45).

Always use a new screw(s) when reinstalling the choke shutter as the screws are treated with dry-type adhesive to secure them in place.

NOTE: NEVER REUSE OLD SCREWS. The choke shaft and plate must be in the closed position

prior to tightening the screws. Hard starting may be due to insufficient choking action because of a misaligned choke plate. Correct by readjusting the choke plate to close completely. Note the cut-out position of choke shutter if applicable.

CHOKE PLATE

FLAT

DOWN

CHOKE PLATE

Fuel Inlet Fitting

Support the carburetor body with a wood block to avoid damage to other parts. Use a bench vise or press to install the fitting squarely . Insert the tip into the carb uretor body, coat the exposed portion of the shank with Loctite grade A, then press it in until the shoulder contacts the carburetor body .

FLAT SIDE DOWN

High and Low Speed Adjusting Screw, Main Nozzle

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When reassembling, position the coil spring on the adjusting screws, follo wed by the small brass w asher and the “O” ring seal. Tur n the high speed adjustment screw in approximately one turn into the bowl retainer nut to make an assembly (diag. 47).

On 2-7 hp. engines that use carburetors which have the metering rod in the idle circuit (carburetor should rattle when shaking), make certain that the idle adjustment screw is installed when the carburetor is in an upright position or the needle will damage the metering rod, adjustment screw and carburetor casting.

Some carburetors are of the fixed main type and would not have a high speed adjusting scre w .

Inlet Needle and Seat

On float type carburetors, make sure the seat cavity is clean. Moisten the seat with oil and insert the seat with the grooved side down and away from the inlet needle. Press the seat into the cavity using a flat punch close to the diameter of the seat, making sure it is firmly seated (diag. 48).

The inlet needle hooks onto the float tab by means of a spring clip. To prevent binding, the long, straight end of the clip should face the air intake end of the carburetor as shown (diag. 49).

On diaphragm carburetors the inlet needle and seat assembly are installed by using a socket to tighten the assembly until seated.

Needle and Seat Pop-Off T est

To test the pop-off pressure, remove the carburetor from the engine. Be sure to drain any fuel into an approved container. Inve rt the carburetor and remove the float bowl. Place a drop of an oil based product such as WD-40 on the tip of the needle valve. Using a commercially available 0-30 psi pump and gauge, attach the pumps hose to the carburetor inlet. Apply approximately 6 psi or until the needle pops off the seat. The needle should seat at 1.5 psi or greater for a minimum of 5 minutes. If the minimum 1.5 psi cannot be maintained for this period of time, then service to the needle and seat is required.

RETAINER NUT

TORQUE NUT TO

50 IN. LBS. (5.65 Nm)

DRIVE IN UNTIL

SEAT RESTS ON

BODY SHOULDER

INLET NEEDLE

SEATS AT THIS

POINT

LONG END

OF CLIP

CHOKE

END

"O" RING

BRASS WASHER

SPRING

HIGH SPEED

ADJUSTMENT SCREW

5/32" FLAT PUNCH

SEAT

INSERT THIS

FACE FIRST

CLIP

OPEN END

OF CLIP

THROTTLE

END

WASHER

INLET SEAT

INLET NEEDLE

FLOAT SPRING

Float Installation

Reinstall the inlet needle and float into the carburetor. The long end of the spring or clip on the inlet needle must point toward the air intake end of the carburetor. If a float dampening spring is used, reassemble using the following steps (diag. 50).

1. Place the float upside down.

2. P osition the spring on the float with the long end around and to the back side of the float’ s center back tang. The ends

3. Place the float, float spring, clip and inlet needle in position between the hinge legs of the carburetor. As the float

HINGE PIN

FLOAT

must point toward the choke end of the carb uretor. Hook the inlet needle clip on the inside float tang so the clip end points to the choke end of the carburetor (diag. 50).

assembly nears the hinge legs, wind the outside end of the spring so it goes to the outside of the leg (counterclockwise looking from the choke end).

4. Install the hinge pin from the opposite hinge leg. The

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bowl gasket must be positioned over the end of the spring (diag. 51).

5. Set the proper float height. See “Float Adjusting Procedure” in this chapter .

GASKET GOES

OVER SPRING

Diaphragm Assembly

The rivet head on the diaphragm must always face toward the inlet needle valve. On carburetors with an “F” cast into the carburetor flange as illustrated, the diaphragm goes next to the carburetor body. Other diaphragm carb uretors have the gasket located between the diaphragm and carburetor body. Install the cover retaining screws and tighten (diag. 52).

Fuel Bowl And Bowl Nut

Whenever a carburetor bowl is removed for service, the fuel bowl “O” ring must be replaced. For easier installation, lubricate the “O” ring with a small amount oil.

Install the float bowl by placing the detent portion opposite of the hinge pin. Make sure the deepest end of the bowl is opposite of the inlet needle. The bo wl has a small dimple located in the deepest part. The purpose of this dimple is to minimize the chances of the float sticking to the bottom of the bowl caused by stale fuel (diag. 53).

On some fixed jet (non-adjustable) and adjustable carburetors, a fibered washer is required between the carburetor bowl and the bowl retaining nut.

RIDGE AND

RIVET

HEAD UP

DETENT

GASKET

CHOKE END OF

CARBURETOR

ENDS OF SPRING POINT

TOWARD CHOKE END

OF CARBURETOR

RIDGE AND

RIVET HEAD

GASKET

Occasionally, on engines equipped with the dual system carburetor, some rich star ting conditions have occurred when the engine is warm. This condition can be corrected by inserting a non-metallic spacer in the center leg of the carburetor, as shown (part # 632158). This spacer is designed to reduce the amount of prime charge in the main nozzle area for better starting under warm engine conditions. It can only be used on Dual System carburetors and does not lean out the carburetor mixture. (diag. 54) This spacer must be reinstalled if originally equipped in the carburetor .

Impulse Fuel Pump

The diaphragms must be installed against the center body with the gaskets against the outside covers. The parts are

designed so they cannot be misassembled without damage (diag. 54).

To test the unit, assemble the carburetor to the engine, leaving the fuel line from the pump off. Use a different fuel tank remotely placed above the carburetor to provide gravity fuel flow to the carburetor inlet to run the engine while testing the pump. Make sure fuel is available in both fuel tanks and that the original fuel tank's fuel line is connected to the fuel pump inlet. Place the pump outlet line in a proper draining receptacle. With the pulse line connected from the engine crankcase to the pump and the engine running, a definite fuel flow should result at the pump outlet.

NON-METALLIC

SPACER

If the flow is erratic or intermittent, the pump needs repair or replacement.

Primer Bulb

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To install, start the retainer and bulb into the casting with the retainer tabs pointed out. Firmly push the bulb and retainer into position using a 3/4'’ (19.05 mm) deep well socket (diag. 55).

Final Checks

Before reinstalling a newly o verhauled carburetor , pre-set the main mixture adjustment screw, the idle mixture adjustment screw and the idle speed adjustment screw. See “Pre-sets and Adjustments” in this chapter .

STANDARD SERVICE CARBURETORS

T ecumseh supplies some replacement carb uretors on which parts from the old carburetors can be reused or new parts added. This Standard Service Carburetor helps to reduce dealer inventories .

Standard Service Carburetors are built in both float and diaphragm versions. The parts from the original carburetor that are necessary to make a standard service carburetor are: choke shaft, shutter

and spring, throttle lever and spring, fuel fitting, idle adjustment screw and spring. If any or all of these old parts are worn or damaged, replace each part with a new service part to assure proper function and prevent engine damage . Use the diagrams on the next page as a guide to f acilitate the correct installation of parts (diag. 57 & 58).

Fuel Fitting

NOTE: MOST SER VICE CARBURETORS ARE MARKED “SVC CARB NF” IN THE PRICE LIST. THIS MEANS THAT

THE CARBURETOR COMES WITH NO FUEL FITTING. Use the parts manual to obtain the same fuel inlet fitting that was installed in the original carburetor. Install the fuel fitting

in the new carburetor body in the same position as on the original carburetor . Support the carburetor body with a wood block to av oid damage to other parts. Use a bench vise or press to install the fitting squarely. Press it in until it bottoms out.

NOTE: PRESS FUEL FITTING IN SQUARELY USING CAUTION SO THAT THE CARBURETOR BODY IS NOT DAMAGED.

Inlet Fuel Fitting

To remove a leaking or damaged fuel inlet fitting, use a 1/4"(6 mm) bolt, 1/4" (6 mm) nut and 1/4" (6 mm) washer , along with a 1/2" (12 mm) nut. Use a pliers or vise to remove the plastic part of the inlet fitting. Tap the inside of the remaining metal portion of the fitting using a 1/4"- 20 (6 mm) tap. Place a 1/2" (12 mm) nut over the fuel fitting (it may be necessary to guide one side of the nut to seat it squarely to the carburetor). Next thread the 1/4" (6 mm) nut on the bolt until it contacts the shank, add the washer, and thread the bolt into the fitting until snug. Tighten the 1/4"- 20 (6 mm) nut until the fitting is removed. (diag. 56)

Choke Shaft

NOTE: Never reuse choke or throttle shutter screws, always replace with new Tecumseh service screws.

Remove the choke shutter scre w from the original carburetor and remov e the choke shaft. Observe the position of the ends of the choke return spring if one is present. Also observe the position of the cut-out and/or holes in choke shutter . Some chokes turn clockwise and some turn counterclockwise, note the position of the choke shaft prior to removal from the old carburetor.

If a choke stop spring is present on the new carburetor and is not used on the old carburetor , cut it off with a side cutter or pull it out using a pliers.

T est the action of chok e shaft to make sure it moves freely and easily and does not bind in either open or closed position. If binding occurs, loosen the shutter screw; reposition the shutter and tighten the screw.

Throttle Lever

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Remove the throttle lever and spring and file off the peened end of the throttle shaft until the lever can be removed. Install the throttle spring and lever on the new carburetor with the self-tapping screw furnished. If dust seals are furnished, install them under the return spr ing.

Idle Speed Adjustment Screw

Remove the screw assemb ly from the original carburetor and install it in the new carburetor . Turn it in until it contacts the throttle lever. Then an additional 1-1/2 turns f or a static setting.

Final Checks

Consult the service section under “Pre-sets and Adjustments” and follow the adjustment procedures before placing the carburetor on the engine.

FLOAT TYPE CARBURETOR DIAPHRAGM TYPE CARBURETOR

CHOKE SHAFT

SELF TAPPING SCREW

THROTTLE LEVER

AND SHAFT

IDLE CRACK

SCREW AND

SPRING

WASHER

FELT SEAL

CHOKE STOP

SPRING

SHUTTER

SCREW

FLOAT

SPRING

LEVER

SPRING

WASHER

FELT SEAL

THROTTLE SHAFT

SHANK

FUEL FITTING

"O" RING

SEAT AND CLIP

INLET NEEDLE

SPRING CLIP

FLOAT SHAFT

FELT SEAL

THROTTLE SHUTTER

SHUTTER SCREW

IDLE

ADJUSTMENT

SCREW

SEAL

WASHER

SPRING

LOW SPEED

ADJUSTMENT

SCREW

SPRING

WASHER

HIGH SPEED

ADJUSTMENT

SCREW

CHOKE LEVER

AND SHAFT

FUEL INLET

CHOKE

SHUTTER

SCREW

DIAPHRAGM

GASKET

DIAPHRAGM

COVER

FLOAT BOWL

BOWL NUT WASHER

HIGH SPEED BOWL NUT

PRIMER FITTING

DIAPHRAGM

COVER SCREW

CHAPTER 4 GOVERNORS AND LINKAGE

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GENERAL INFORMATION

This chapter includes governor assembly and linkage illustrations to aid in governor or speed control assembly. Tecumseh 4 cycle engines are equipped with mechanical type governors. The governor’s function is to maintain a

constant R.P.M. setting when engine loads are added or taken away. Mechanical type governors are driven off the engine’s camshaft gear. Changes in engine R.P.M. cause the governor to move the solid link that is connected from the governor lever to the throttle in the carb uretor. The throttle is opened when the engine R.P.M. drops and closes as the engine load is removed.

OPERATION

As the speed of the engine increases, the governor weights (on the governor gear) move outward by centrifugal force. The shape of the go vernor weights force the governor spool to lift. The governor rod maintains contact with the governor spool due to the governor spring tension. As the spool rises, the governor rod rotates, causing the attached outer governor lever to pull the solid link and close the throttle opening. When the engine speed decreases, the lower centrifugal force allows the governor weights to be pulled in by the governor spring. As the spool lowers, the governor rod rotates and the solid link pushes the throttle to a more open position (diag.

1).

INTERNAL COMPONENTS (VARIOUS STYLES)

RETAINING

RING

SPOOL

RETAINING

RING

GEAR ASSY.

(GOV.)

WASHER

SHAFT

SPOOL

UPSET

NO RETAINING

RING

SHAFT

GEAR ASSY.

(GOV.)

WASHER

RETAINING

THROTTLE

RING

SPOOL

WASHER

RETAINING

RING

GEAR ASSY.

(GOV.)

WASHER

SPACER

SHAFT

GOVERNOR SHAFT

WEIGHTS

GOVERNOR GEAR

SHAFT

ROD

ASSY

(GOV.)

WASHER

BRACKET

RETAINING

SPRING

SPOOL

RING

GEAR

ASSY.

(GOV)

GOVERNOR

SPOOL

SHAFT

GEAR ASSY. (GOV.)

WASHER

TROUBLESHOO TING

Engine problems where the governor is suspected to be the cause, ma y actually be the result of other engine system problems. Hunting (engine R.P.M. surging up and down) indicates that the engine is incapable of maintaining a constant R.P.M. with or without an engine load. Engine overspeeding (either with or without throttle movement) must be corrected immediately before serious engine damage occurs. Use the following procedure to diagnose a suspected governor problems.

TVS STANDARD

SCREWS

TVS UPSET HORIZONTAL LEV

MEDIUM FRAME

ENGINE OVERSPEEDING

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1. If the engine runs wide open (faster than normal), shut the engine off immediately.

2. Check the condition of the external governor shaft, linkage, governor spring, and speed control assembly for breakage, stretching or binding. Correct or replace binding or damaged parts.

3. Follow the governor adjustment procedure and reset the governor - see "Service" in this chapter.

4. Run the engine. Be ready to shut the engine off if an overspeed problem still exists. If the problem persists, the engine will require disassembly to inspect the governor gear assembly for damage, binding, or wear.

5. See Chapter 9 under "Disassembly Procedure" to disassemble the engine.

6. Remove the governor gear assembly. Repair or replace as necessary.

ENGINE SURGING

1. Try to stabilize the engine R.P.M. by holding steady the solid link between the governor arm and the carburetor throttle, using a pliers or fingers.

2. If the engine R.P.M. stabilizes, the governor or governor adjustment should be checked. See "Ser vice" governor adjustment procedure in this chapter. If the engine R.P.M. does not stabilize, the engine will require additional checks, see Chapter 9 under "Troubleshooting".

3. If the problem persists after the gov ernor adjustment, check the engine R.P.M. f ound on microfiche card # 30. The R.P.M. settings are critical. If the R.P.M. setting for high and low speed are within specification and a slight surge is experienced, increasing the engine idle R.P.M. setting slightly may eliminate this condition.

4. Check the gov ernor shaft or linkages for binding, wear , or improper hookup. Check the gov ernor spring for adequate tension. Repair or replace as necessary.

SERVICE GOVERNOR ADJUSTMENT

With the engine stopped, loosen the screw holding the governor clamp on the governor lev er. Rotate the clamp in a direction that will force the throttle shaft open and allow the governor follower arm to rest on the governor spool. Push the go v ernor lever connected to the throttle to the wide open throttle position. Hold the lever and clamp in this position while tightening the screw (diag.

7).

GOVERNOR ADJUSTMENT PR OCEDURE FOR SHORT BLOCK INSTALLATIONS

Short block installation on 3-5 h.p. v ertical shaft engines built prior to 1977 may require the governor clamp (tinnerman style) to be repositioned to work properly. The clamp must be removed from the gov ernor rod and turned to the same position as the original engine. Hook the solid link and spring to the governor lever and position the clamp on the governor rod. Follow the abov e governor adjustment procedure to complete the short block governor set-up. Units built after 1977 use the normal governor set up procedure. (diag. 8)

GOVERNOR SHAFT

GOVERNOR SPOOL

GOVERNOR GEAR

PUSH LEVER

TO OPEN

THROTTLE

Figure A

Before 1977

production

VERTICAL

Figure B

1977 & Later

production

GOVERNOR GEAR AND SHAFT SERVICE

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After the cylinder cover is removed from the engine, the governor spool, gear, or governor shaft can be removed. On older style governor assemblies, the retaining ring must be removed to allow the spool or gear to slide off the shaft. Newer style gov ernor shafts (3 - 6.75 model engines) use an upset to hold the governor spool on. If the gear requires replacement, the governor shaft will have to be removed.

Governor Spool Replacement With Upset Style Governor Shaft

The spool can be replaced without removing the governor shaft. Grip the original spool in a vise and use a twisting and pulling motion on the flange until the spool is free.

Install the new spool by starting it on the shaft and then turning the flange over. This will allow the weights to hang in the proper position. Place the spool on a solid surface and push on the flange until the spool seats. The gov ernor weights must be in position under the spool after installation. (diag. 9)

Governor Gear or Shaft Replacement, Upset Style Governor Shaft

1. Grip the original spool in a vise and use a twisting and pulling motion on the flange until the spool is free.

2. Clamp the shaft in a vise and pound gently on the flange with a wooden or plastic mallet to remove the shaft.

NOTE: DO NO T TWIST THE SHAFT WHEN REMO VING. THE SHAFT BOSS MAY BECOME ENLARGED, LEA VING THE NEW GOVERNOR SHAFT LOOSE AND CAUSING SEVERE DAMAGE.

3. To install a new shaft, first assemble the gear and

4. Place the flange in a press with a solid piece

Governor Shaft Replacement, Retaining Ring Style

1. Remove the retaining ring, spool, gear assemb ly , and

2. Clamp the shaft in a vise and pound gently on the

NOTE: DO NO T TWIST THE SHAFT WHEN REMO VING. THE SHAFT BOSS MAY BECOME ENLARGED AND THE NEW GOVERNOR SHAFT WILL BE LOOSE AND MOVE.

3. Start the new shaft into the shaft boss by tapping

4. Refer to the chart at right for the proper shaft e xposed

5. Reassemble the gover nor and install the retaining

washer on the shaft. Start the shaft into the hole with a few taps from a soft faced hammer.

supporting the area below the shaft boss. Press the shaft in until a shim, part # 670297 just becomes snug [.010 - .020 (.254 - .508 mm) clearance].

washers.

flange with a wooden or plastic mallet to remove the shaft.

with a soft faced hammer.

length. Add a drop of red Loctite 271 and press the governor shaft to the proper depth using a press or a vise. Wipe the e xtra Loctite off after installation (diag.

11).

ring.

WASHER

ENGINE MODEL

ECH90 ECV100 H 30, 35 HS 40, 50 LAV 35 LEV (all) OHH (all) OVRM (all) TNT 100, 120 TVS (all)

TVM (all) V 50, 60, 70 VH 50, 60, 70

HH 100, 120 VH 100

H 50, 60, 70 HH 60, 70 HHM80 HM 70, 80, 100

GEAR

SHIM

SHAFT BOSS

670297 (modified)

EXPOSED SHAFT LENGTH

Mounting flange to Top

1.319 - 1.334" (33.502 - 33.883 mm)

Mounting flange to Top

1.581 - 1.596" (25.806 - 26.314 mm)

Mounting flange to Top

1.016 - 1.036" (25.806 - 26.314 mm)

Mounting flange to Shoulder

1.283 - 1.293" (32.588 - 32.842 mm)

SPEED CONTROLS AND LINKAGE

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Many different types of speed controls and linkage are used for O.E.M. applications. Linkage attachment points are best recorded or marked prior to disassembly. This assures the correct placement during reassembly. The solid link is always connected from the outermost hole in the governor lever to the throttle in the carburetor. The link with the governor spring attached is connected between the control lever and the lower hole in the governor lever. Horizontal engines use one location (non-adjustable) speed control brackets. Most vertical engines use an adjustable speed control bracket mounted above the carburetor. The ignition ground out switch, idle R.P.M. and high speed R.P.M. adjustment screws are located on the speed control brack et and some models use the idle R.P.M. adjustment on the carburetor.

Vertical shaft engines must have the speed control bracket aligned when installing. To align the control bracket, use the following steps.

1. Loosen the two screws on the top of the panel.

2. Move the control lever to full wide open throttle position and install a wire or aligning pin through the hole in the top of the panel, the hole in the choke actuating lever, and the hole in the choke (diag. 12).

3. With the components aligned, tighten the two screws on the control panel.

The following pages illustrate common linkage attachment. Whenever the carburetor or the governor linkage is removed or replaced, the engine R.P.M.'s should also be checked. Use microfiche card #30 or the computer parts look-up system for the correct R.P.M. settings for the engine model and specification.

SNAP IN "STYLE SPEED CONTROL"

This style of speed control is used on 3 - 6.75 model rotary mower engines and is adjusted by two bendable tabs. Use the speed adjustment tool (part # 670326) as illustrated in diag.13 to adjust engine speed.

To adjust high speed, move the speed control lever to the high speed position and align the high speed pin holes. Place the adjustment tool on the high speed tab and move the tab to achieve the correct engine speed. Move the speed control lever to the low speed position, place the adjustment tool on the low speed tab and bend to either increase or decrease to the correct speed.

LOOSEN TO ADJUST

CONTROL LEVER

LOW SPEED TAB

HIGH SPEED PIN POSITION

HIGH SPEED TAB

DECREASE

INCREASE

TOOL 670326

WIRE

HOLE

ADJUSTING RPM ON MEDIUM FRAME

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VERTICAL SPEED CONTROL

This speed control is adjusted to the equipment throttle control by aligning the slot in the speed control lev er with the alignment hole on the mounting bracket. Place a pin through the two holes, place the equipment throttle control to the wide open position, hook the bowden cable end in the control as shown, and tighten the cable housing clamp. In this position, the gap of .040" - .070" (1.016 - 1.778 mm) should exist at the gap location as illustrated. This will assure that the carburetor will go into full choke when the control is placed in the start position.

ADJUSTING GOVERNED/NON-GO VERNED

With the engine running at its lowest speed, set the governed idle at the designated RPM by adjusting the governed idle screw or bending the idle tab . Next set the non-governed idle by pushing the bottom of the gov ernor lever away from the control brackets so the throttle lever contacts the idle speed crack screw (on the carburetor). Hold the lever in this position and turn the crack scre w to 600 RPM below the governed idle speed. This setting prevents the throttle plate from closing off when going from high speed RPM to low speed RPM. If improperly adjusted, the engine could experience an over lean condition.

The idle speed is adjusted by turning the idle speed screw clockwise to increase engine R.P.M. and counterclockwise to decrease R.P.M. Use tool part # 670326 to adjust the high speed engine R.P.M. Place the slotted end of the tool onto the adjustment tab and bend the tab to the left (toward the spark plug end) to increase engine R.P.M. (diag. 14).

HIGH SPEED

ADJUSTMENT TAB

TOOL

670326

DECREASE

HIGH SPEED

ADJUSTMENT TAB

BEND AREA

GOVERNED

IDLE ADJUSTING

SCREW

GOVERNED

IDLE SPEED SCREW

GAP OF

.040 - .070

(1.016 - 1.778 mm)

INCREASE

.040 - .070 (1.016 - 1.778 mm)

GAP LOCATION

CHOKE ADJUSTING

TOOL

670326

HIGH SPEED

PIN POSITION

TAB

CONTROL

LEVER

HIGH SPEED

PIN POSITION

DECREASE

INCREASE

NOTE: Some engines use nylon bushings on the throttle and choke linkage hook-up points to extend the life of the linkage and to enhance the stability of the governor system. Mak e sure they are in good condition and in place.

ADJUSTING RPM ON MEDIUM FRAME VERTICAL (up/down speed control)

T o adjust the high speed RPM on Medium F rame V ertical engines, move the control lever to the high speed pin position (align high speed pin holes in the speed control bracket). Place the slot on the straight end of tool (number

670326) onto the high speed adjustment tab as pictured. Rotate the bent end of the tool counterclockwise to increase RPM and clockwise to decrease RPM. (diag.

15).

HORIZONTAL SHAFT ENGINES

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IDLE SPEED

CRACK SCREW

HORIZONTAL LIGHTWEIGHT

IDLE SPEED

CRACK SCREW

HIGH SPEED

RPM

ADJUSTMENT

SCREW

IDLE SPEED

CRACK SCREW

LIGHTWEIGHT R.V. TYPE

HIGH SPEED

RPM

ADJUSTMENT

SCREW

HIGH SPEED

RPM

ADJUSTMENT

SCREW

IDLE SPEED

CRACK SCREW

HORIZONTAL MEDIUM FRAME

HIGH SPEED RPM

ADJUSTMENT SCREW

IDLE

MIXTURE

SCREW

MAIN

MIXTURE

SCREW

SMALL FRAME

IDLE SPEED CRACK SCREW

HIGH SPEED RPM

ADJUSTMENT SCREW

CONSTANT SPEED APPLICATIONS

HORIZONTAL SHAFT ENGINES (CONTINUED)

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HIGH SPEED RPM

ADJUSTMENT SCREW

IDLE SPEED

SCREW

IDLE MIXTURE

SCREW

IDLE SPEED

CRACK SCREW

HORIZONTAL MEDIUM FRAME

IDLE MIXTURE

IDLE SPEED

CRACK SCREW

HIGH SPEED RPM

ADUSTMENT SCREW

MEDIUM FRAME

SCREW

HMSK80-100

MAIN MIXTURE

SCREW

BEND LOOP OPEN OR

CLOSED TO ATTAIN

OPERATING RPM'S

SNOW KING ENGINES

IDLE SPEED

CRACK SCREW

MAIN MIXTURE

SCREW

TO INCREASE SPEED - CLOSE LOOP

TO DECREASE SPEED - SPREAD LOOP

SNOW KING ENGINES

VERTICAL SHAFT ENGINES

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HIGH SPEED

ADJUSTMENT

SCREW

IDLE SPEED

CRACK SCREW

VERTICAL SHAFT ENGINES

BEND Ó TO INCREASE SPEED

BEND Ô TO DECREASE SPEED

TNT 100 VERTICAL ENGINES

TVS 115 ENGINE WITH "SNAP IN"

SPEED CONTROL

IDLE SPEED

CRACK SCREW

IDLE MIXTURE

SCREW

TVXL 220 WITH HORIZONTAL SPEED CONTROL

STANDARD TVM ENGINE WITHOUT GOVERNOR

OVERRIDE

3029

GOVERNOR OVERRIDE SYSTEM FOR

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TVM170, 195 AND 220 ENGINES

This system will be found starting on 1985 production models, and will not retrofit onto older engines. It is designed to allow the governor to regulate the low and high speeds of the engine. The high speed is adjusted at the top screw of the override lever; to increase R.P.M. turn the screw out (counterclockwise), to decrease R.P.M. turn the screw in (clockwise). The low speed is adjusted at the bottom screw of the override lever; to increase R.P.M. turn the screw in or clockwise, to decrease R.P.M. turn the screw out or counterclockwise (diag. 31).

GO VERNED / NON-GOVERNED IDLE

With the engine throttle set at its lowest speed, set the governed idle at the designated RPM by bending the idle RPM tab or adjusting a screw . Next set the non-go verned idle by pushing the bottom of the governor lever away from the control brackets, so the throttle lever contacts the idle speed screw. Hold the lever in this position and turn the idle adjustment screw clockwise to increase or counterclockwise to decrease engine idle speed. The setting on the carburetor screw should be set 600 RPM below the governed idle setting. This setting pre v ents the throttle plate from closing when going from high speed RPM to low speed RPM. If improperly adjusted, the engine could experience an over lead condition.

MAIN MIXTURE

SCREW

HIGH SPEED

ADJUSTMENT SCREW

LOW SPEED ADJUSTMENT SCREW

TVM ENGINES WITH GOVERNOR OVERRIDE

CHAPTER 5 REWIND STARTERS

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GENERAL INFORMATION

Rewind starters used on vertical shaft Tecumseh engines are top mount horizontal pull style or side mount vertical pull style. Horizontal shaft engines use side mounted starters which can be mounted to pull either vertically or horizontally. All rewind starters except the vertical pull style turn the engine over by engaging a dog(s) into the starter cup attached to the engine flywheel. The vertical pull starter engages the starter gear into the ring gear of the flywheel to tur n the engine over. All starters are spr ing loaded to retract the dog(s) or starter gear when the engine speed exceeds the turning speed of the star ter.

OPERATION

As the starter rope is pulled, the starter pulley rotates on the center pin. The starter dog(s) is pinned or pocketed in the pulley hub and extends outw ard when the pulley's rotation f orces the starter dog(s) to contact the ears on the retainer. The retainer ears act as a ramp to fully extend the starter dog(s). The fully extended star ter dog(s) locks in contact with notches in the starter cup. When the engine fires and the rotational speed of the starter cup exceeds the starter pulley, the star ter dog(s) disengages from the starter cup. The starter dog spring(s) returns the starter dog(s) to the disengaged position. The recoil spring turns the starter pulley in the opposite direction, retracting the starter rope until the handle contacts the stop.

COMPONENTS

HANDLE

ROPE

PULLEY AND REWIND

SPRING ASSY.

STARTER DOG

STARTER HOUSING

DOG SPRING

WASHER

RETAINER

BRAKE SPRING

WASHER

SPRING PIN

HANDLE

DOG SPRING

RETAINER

BRAKE SPRING

HOUSING

SPRING & KEEPER

PULLEY

DOG

BRAKE WASHER

CAM DOG

CENTER SCREW

SERVICE

Starter related problems will require the starter to be removed from the engine to diagnose the cause. Visually inspect the starter dog(s), starter cup, retainer, springs, rope, washers, and the starter pulley for wear or breakage. Use one of the following procedures that applies to your application, to disassemble, repair, and assemble the starter. Always consult the Tecumseh Master Parts Manual for the correct replacement parts.

ROPE SERVICE

Rope replacement should be done using the correct part number replacement rope or braided rope of the correct diameter and length. Consult the Tecumseh Master Parts Manual to obtain the correct part number, length, and size required. Use the following rope chart to convert a numbered rope to a fractional diameter for bulk rope use.

# 4 1/2 rope = 9/64" (3.572 mm) diameter Part No. 730526 100' (30.48 meters) spool # 5 rope = 5/32" (3.964 mm) diameter Part No. 730514 100' (30.48 meters) spool # 6 rope = 3/16" (4.762 mm) diameter Part No. 730516 100' (30.48 meters) spool

Standard rope lengths

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54" (16.5 meters) standard stamped steel star ter 61" (18.6 meters) vertical pull - horizontal engagement

type

65" (20 meters) ver tical pull - vertical engagement

type

85" (26 meters) extended handlebar rope start

(compliance)

Check the old rope for the right length for the application. Some applications require longer lengths. The rope ends should be cauterized by burning with a match and wiping the rope end with a cloth while hot.

LEFT-HAND

KNOT

Rope replacement can be done without the starter being disassembled on vertical pull starters that have "V" notches in the bracket. Use the following procedure for rope replacement.

1. Remove the starter assembly from the engine.

2. Turn the pulley until the staple in the pulley lines up with the "V" notch. Pry out the staple with a small screwdriver and remove the original rope (diag. 3).

3. Turn the pulley counterclockwise to fully wind the starter return spring until tight. Allow the pulley to unwind until the hole in the pulley lines up with the "V" notch.

4. Hold the pulley in this position and f eed the new rope through the hole and tie a left-handed knot on the rope end. Make sure the rope and knot do not protrude from the knot cavity and bind the pulley rotation.

RETAINER REPLACEMENT (DIAGRAM 4)

1. Remove the starter handle if the retainer is a complete circle design. Remove the staple and old retainer.

2. Slide the rope retainer into the proper position and insert the staple using a pliers.

3. Install the starter handle and tie a left hand knot to secure the handle.

STYLIZED REWIND ST ARTER (TVS, HM, TVM, TVXL), AND ST AMPED STEEL ST A RTER (HM, VM, TVM, TVXL)

ONE PIECE ROPE RETAINER

HANDLE

ROPE

PULLEY AND REWIND

SPRING ASSY.

STARTER DOG

STARTER HOUSING

DOG SPRING

WASHER

RETAINER

BRAKE SPRING

WASHER

SPRING PIN

Disassembly Procedure

1. After removing the rewind assemb ly from the engine

2. Place a 1" (25 mm) deep well socket under the

3. Use a 5/16" (7.938 mm) or 1/4" (6.35 mm) (for

blower housing, release the tension on the rewind spring. This can be done by removing the starter handle and carefully allowing the rope to unwind in the starter housing assembly.

retainer. Set the rewind on a bench, suppor ted on the socket.

stamped steel) roll pin punch to drive out the center pin. The stamped steel center pin is driven out from the top, inside the center hole. Mov e the punch around while driving the pin to help keep the pin straight.

CAUTION: THIS REWIND SPRING IS NOT SECURED IN A CANISTER. PULLEY BOSSES HOLD THE

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REWIND SPRING AND COVER, AND CAN BE EASILY DISLODGED DURING HANDLING.

4. Remove the brake spring, spring retainer, washers, and pulley assembly (diag. 7, 8, 9 & 10)

NOTE: THE STARTER DOGS FACE OUT ON THE STAMPED STEEL STAR TER AND THE DOGS FACE IN ON THE STYLIZED REWIND STARTER.

5. All components in need of service should be replaced.

SPRING PIN 1/8"

FROM TOP

Assembly Procedure

STARTER HOUSING

LEFT-HAND

KNOT

HANDLE

NOTE: It is critical to support the starter on a deep well socket to prevent damage.

1. Reverse the disassemb ly procedure. The starter dogs with the dog springs must snap back to the center of the pulley (disengaged position). When the rope is pulled, the tabs on the retainer must be positioned so that they will force the starter dogs to engage the starter cup. (diag. 7 & 8)

2. Always replace the center spring pin with a new one upon reassembly. Place the two new plastic washers between the center leg of the starter and the retainer. New plastic washers are provided with a new center spring pin. Discard the old plastic washer.

ROPE

HANDLE INSERT

PULLEY AND REWIND

SPRING ASSY.

STARTER DOG

BRAKE SPRING

SPRING PIN

DOG SPRING

WASHER

RETAINER

WASHER

3. Place the rewind on a flat surface and drive the new center pin in until it is within 1/8" (3.175 mm) of the top of the starter.

NOTE: DO NO T DRIVE THE CENTER PIN IN TOO FAR.

The retainer will bend and the starter dogs will not engage the starter cup. On the stamped steel starter the center pin should be driven in until it contacts the shoulder in the starter body.

4. Wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring, thread the rope through the starter housing eyelet and tie a temporary knot in the rope. Reattach the starter handle to the rope using a left-hand knot. Untie the tempor ary knot and allow the rope to recoil.

STYLIZED REWIND STARTER WITH PLASTIC RETAINER

Disassembly Procedure

1. After removing the rewind assembly from the engine blower housing, remove the starter handle by first pulling a length of rope out using the handle, tying a temporary knot in the exposed rope, and either untying the knot in the handle or prying out the staple.

2. Untie the temporar y knot and slowly allow the rope to fully retract into the starter housing and the recoil spring to fully unwind.

3. Remove the decal from the center of the starter housing.

SPRING PIN 1/8"

FROM TOP

STARTER

HOUSING

HANDLE

ROPE

PULLEY AND REWIND

SPRING ASSY.

DOG SPRING

STARTER DOG

WASHER

RETAINER

BRAKE SPRING

WASHER

SPRING PIN

4. Use a small Phillips screwdriver or similar tool to pry the retainer legs apart and lift out the retaining wedge (or steel clip on newer style starters).

5. Pinch the legs of the retainer together and pull on the head of the retainer to remove it from the housing.

6. Remove the pulley assembly from the recoil housing.

7. Repair or replace as necessar y.

Assembly

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1. If replacing the starter rope, see Step 8.

Extreme caution should be used when working with springs. Always where appropriate safety equipment.

2. Install a new recoil spring if necessar y by pushing the new spring out of the holder into the pulley cavity while aligning the outside spring hook into the deep notch in the pulley. Push the spring cover in until seated.

3. Apply a small amount of lithium grease to the inner bore of the center shaft.

LEFT-HAND

KNOT

RETAINING WEDGE

(STEEL CLIP - NEW STYLE)

STARTER

HOUSING

STARTER PULLEY

SPRING & COVER

4. Replace or check that both starter dogs are in the pulley pockets and that the dog springs are hooked on the outer surface of the dog.

5. Pinch the two legs of the plastic retainer together and start into the center shaft hole.

6. Rotate the retainer so the two tabs on the bottom of the part fit between the dog and pulley hub (left side of the dog). Push the retainer in until the leg prongs pop out of the center shaft.

7. Turn the starter over and snap the locking tab between the retainer legs, replace the top decal.

NOTE: Ref er to Service Bulletin 122 for steel locking clip.

8. Wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring and thread the rope through the starter housing eyelet. Pull enough rope through to tie a temporary knot in the rope. Reattach the starter handle to the rope using a left-hand knot. Untie the temporary knot and allow the rope to recoil.

STANDARD STAMPED STEEL AND CAST ALUMINUM STARTER (HM, VM)

Disassembly Procedure

1. Untie the knot in the rope and slowly release the spring tension.

HANDLE

DOG SPRING

STARTER DOG

DOG RETAINER

STARTER

HOUSING

REWIND

SPRING AND

KEEPER ASSY.

2. Remove the retainer screw, retainer cup (cam dog

3. Turn the spring and keeper assembly to remove the

Assembly Procedure

1. Place the rewind spring and keeper assembly into

on snow proof type), starter dog(s) and dog spring(s), and brake spring (diag. 10).

pulley. Lift the pulley out of the starter housing. Replace all worn or damaged parts.

the pulley. Turn the pulley to lock into position. A light coating of non-freeze grease should be applied on the spring.

HANDLE INSERT

ROPE

PULLEY

CAM DOG

WASHER

DOG SPRING

STARTER DOG

DOG RETAINER

RETAINER SCREW

BRAKE SPRING

SPRING PIN

2. Place the pulley assembly into the starter housing.

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3. Install the brake spring, star ter dog(s), and starter dog return spring(s). The starter dog spr ing(s) must hold the dog(s) in against the pulley. On Snow King engines the starter dog posts should be lubricated with S.A.E. 30 engine oil.

4. Replace the retainer cup (cam dog on snow proof starter) and retainer screw. Tighten to 65 - 75 in. lbs. Older models that use a 10 - 32 retainer screw can be replaced with a larger 12 - 28 screw (part # 590409A). Re-drill the screw hole using a 13/64" (4.35 mm) drill bit. The center screw torque on cast aluminum starters is 115 to 135 in. lbs (13 - 15 Nm) (diag. 11 & 12).

5. Add-on alternator starters must have the center tubular rivet replaced each time the tubular rivet is removed. The tubular rivet should be pressed to a depth of 1/4" (3.175 mm) from the top of the starter housing. Skip this step if not applicable.

6. Apply tension to the recoil spring by winding the pulley counterclockwise until it becomes tight, then allow the pulley to unwind until the hole in the pulley lines up with the rope eyelet in the starter housing. Install a knotted rope through the pulley and the eyelet and install the handle. A left-hand knot should be tied on the end of the rope to secure the handle.

LEFT-HAND

KNOT

HANDLE

BRAKE SPRING

HANDLE

HOUSING

SPRING &

KEEPER ASSY.

PULLEY

DOG SPRNG

RETAINER

RETAINER SCREW

CENTER PIN

HOUSING

7. If a center ing pin is used, be sure to align with the crankshaft (bottom pin in center screw hole). Install nylon sleev e 1/8" (3.175 mm) onto pin. P osition nylon sleeve in aligning recess in the crankshaft. START two mounting screws in blower housing 90o apart. With sleeve centered in crankshaft, gently push the starter in place, tighten the two mounting screws, insert and tighten the other two screws.

VERTICAL PULL STARTER HORIZONTAL ENGAGEMENT TYPE

Disassembly Procedure

1. Remove the handle and relieve the starter spring tension by allowing the rope to slip past the rope clip .

2. Remove the spring cover by carefully removing the two small screws. Carefully take out the spring.

3. Remove the center hub screw and the spring hub.

4. Lift off the gear and pulley assembly. Disassemble the pulley assembly by removing the snap ring and washer (diag. 13).

DOG SPRING

RETAINER

BRAKE SPRING

HANDLE

ROPE CLIP

THRUST WASHER

MOUNTING

BRACKET

AND SNAP SCREW

SPRING &

KEEPER

PULLEY

DOG

BRAKE WASHER

CAM DOG

CENTER SCREW

GEAR

BRAKE SPRING

PULLEY

ROPE

SPRING HUB

SCREW

SPRING

SCREW

COVER

5. Remove the starter rope if necessar y. Replace all

worn or damaged parts.

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Assembly Procedure

1. Insert the rope through the starter pulley.

LEFT-HAND

KNOT

2. Assemble the gear, pulley, washer, and snap ring.

3. Place a small amount of grease on the center shaft, place the gear and pulley into position making sure the brake spring loop is positioned over the metal tab on the bracket. The rope clip must fit tightly onto the bracket. The raised section fits into the hole in the bracket (diag. 14 & 15).

4. Install the hub and hub screw. Torque the hub screw to 45 - 55 in. lbs. (5 - 6 Nm). A loose hub screw will prevent the rope from retracting.

5. Install the return spring if necessary. A replacement spring is installed by placing the spring and its retainer over the top of the pulley and pushing the spring out of the retainer into the pulley's recessed area.

6. Install the spr ing cover and the cover screws.

7. Wind the rope onto the pulley by slipping it past the rope clip. When the rope is fully wound on the pulley , wind the pulley assembly two additional turns to put tension on the spring.

8. Mount the starter on the engine making sure the top of the starter gear teeth are no closer than 1/16" (1.59 mm) from the top of the flywheel ring gear teeth.

ROPE CLIP

RECEPTACLE

FOR RAISED

SECTION

RAISED SPOT

MOUNTING BRACKET

TAB MUST FIT INTO

SPRING LOOP

BRAKE

VERTICAL PULL STARTER, VERTICAL ENGAGEMENT TYPE

Disassembly Procedure

1. Pull out enough rope to lock the rope in the "V" of the bracket.

2. Remove the handle if necessary by prying out the small staple in the handle with a screwdriver.

3. Place the star ter bracket on the top of a deep well socket that is large enough to receive the head of the center pin. Use an arbor press to drive out the center pin.

4. Rotate the spring capsule strut until it is aligned with the legs of the brake spring. Insert a nail or pin no longer than 3/4" (19.05 mm) through the hole in the strut so it catches in the gear teeth. This will k eep the capsule in the wound position (diag. 16).

5. Slip the sheave out of the bracket.

CAUTION: DO NOT ATTEMPT TO REMO VE THE SPRING CAPSULE FROM THE SHEAVE ASSEMBLY UNLESS THE SPRING IS FULLY UNWOUND.

ROTATE

COUNTERCLOCKWISE

STRUT

6. Squeeze and hold tightly by hand the spring capsule

at the outer edge against the gear sheave.

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7. Remove the retainer pin from the strut and slowly relieve the spring tension by allowing the spring capsule to rotate slowly under control, until completely unwound. The spr ing capsule can now be removed from the gear sheave.

Assembly Procedure

ORIGINAL INSTALLATION WITH STAPLE

INSTALL NEW

ROPE BY TYING

LEFT-HAND

KNOT

LEFT-HAND

KNOT

1. Feed the new rope through the hole and tie a lefthanded knot on the rope end. Make sure the rope and knot do not protrude from the knot cavity and bind the pulley rotation (diag. 17).

2. Wind the rope on the sheave assembly clockwise, viewing the gear from the gear side of the sheave.

3. Reinstall the brake spring, being careful not to spread the spring more than necessary.

4. Install the spr ing capsule, making sure the starter spring end hooks on the gear hub (diag. 18).

5. Wind the spr ing four full turns and align the brake spring legs with the strut as shown. Insert the pin in the strut (diag. 19).

6. If the starter is equipped with a locking or delay pawl and spring, make sure these are in place before grasping the gear and spring capsule assembly and sliding it into the bracket. Make sure the legs of the brake spring are positioned in the slots of the brack et.

7. Feed the rope end under the rope guide and hook it into the "V" notch. Remove the pin and the strut will rotate clockwise against the bracket (diag. 21).

8. Inser t the new center pin by pressing or driving the pin firmly in place. Reinstall the starter assembly on the engine (diag. 21).

GEAR HUB

STARTER SPRING

END

SPRING HOOKED ON

GEAR HUB

REINSTALL

LEFT-HANDED

KNOT

ROTATE SPRING

PRY STAPLE

OUT TO

REMOVE OLD

ROPE

4 FULL TURNS

PAWL SPRING *

"V"ROPE WEDGE

BRAKE

CLIP *

KEY*

ROPE CLIP

BRACKET

STARTER HANDLE

ROPE

PULLEY

* USED ON SOME MODELS

SPRING

ASSY.

STRUT

PAWL

LOCKING PAWL*

GUIDE BRAKE ENDS

THROUGH SLOT

WHEN PIN IS REMOVED STRUT

WILL ROTATE 45o CLOCKWISE

CHAPTER 6 ELECTRICAL SYSTEMS

Main Menu

GENERAL INFORMATION

The electrical system consists of three main elements: a battery, a starting circuit, and a charging circuit. The battery is part of both the starting and charging circuit. The battery should be checked before going into any extensive starter or charging system checks. If a battery has a shorted cell, overcharging can result, and the regulator or rectifier may appear to be at fault. If a cell has an open or high resistance connection, the electric starter operation will be affected.

The power source used to provide the energy to turn an electric starter motor on Tecumseh engines is either 120 volt A.C. current or 12 volt D.C. An A.C. starter circuit utilizes a 120 volt power source instead of a battery. The 12 volt battery models require a charging system to maintain proper batter y charge.

The starting circuit includes the batter y, battery cables, starter or ignition switch, safety switches, and an electric starter motor.

The charging system consists of alternator charge coils, rectifiers or diodes, regulator, ignition s witch, flywheel magnets, and a battery. All engines that have a charging system will use a combination of some or all of these features.

OPERATION

STARTING CIRCUIT AND ELECTRIC STARTERS

After all of the safety interlock switches have been activated, the starter switch will complete the circuit. A strong magnetic force is produced by the electrical current running through the armature windings. The armature magnetism repels the magnetism produced by the permanent field magnets of the electric starter. The repelling magnetic forces cause the armature to rotate, moving the drive pinion laterally on the splined armature shaft, meshing the starter pinion gear with the flywheel ring gear. When the drive pinion contacts the stop at the end of the armature shaft, the pinion rotates along with the armature shaft to crank the engine. The armature and pinion remain positively engaged until the engine fires and the flywheel rotates faster than the armature. The greater momentum of the flywheel throws the starter pinion gear out of mesh and forces the starter pinion back to the disengaged position. After the switch is released, the starting circuit is opened and the armature coasts to a stop. A small anti-dr ift spring holds the pinion in the disengaged position (diag. 1).

CHARGING CIRCUIT

When a conductor (alternating coils) cuts the magnetic field generated by the magnets in the flywheel, a current will be induced in the alternator coil. The permanent magnets in the flywheel have a magnetic field in which the lines of magnetic force run from the North Pole to the South Pole. As the flywheel rotates and the position of the magnets change, the direction of the magnetic field changes or alternates. The alternating coils are wound in different directions to allow current to flow as an A.C. wavefor m (diag. 2).

BRUSH CARD

HOUSING

SPRING

RETAINER

BRUSHES

BRUSH SPRINGS

DUST COVER

ROTA TION OF FLYWHEEL

SPRING

LOCK NUT

BOLT

GEAR

END CAP

WASHER

NUTS

ARMATURE

THRUST WASHER

END CAP

ENGAGING NUT

CONVERTING ALTERNATING CURRENT TO

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DIRECT CURRENT

ANODE

CATHODE

In order to charge a battery, it is necessary to convert alternating current (A.C.) to direct current (D.C.). This is accomplished by using a diode or rectifier (diag. 3). A

DIRECTION OR FLOW OF CURRENT

BAND OR OTHER

MARKING INDICATES

CATHODE END

single diode makes use of only one half of the A.C. signal and is known as HALF W AVE RECTIFICA TION (diag. 4). This is acceptable in certain applications. In certain

situations it is necessary to make use of the entire A.C. signal. To accomplish this, multiple diodes in a bridge configuration are used to produce FULL WAVE RECTIFICATION (diag. 5).

Current flows through a diode when the anode is more positive than the cathode. The cathode end of the diode should point toward the battery when diode is used between a charging system and a battery.

HALF WAVE RECTIFIER SINGLE DIODE

The single diode allows only the positive half of the A.C. signal through. It does not allow the negative portion through.

HALF WAVE RECTIFIER

+ VOLTAGE

(SINGLE DIODE)

+ VOLTAGE

A.C. INPUT

- VOLTAGE

FULL WAVE RECTIFIER (BRIDGE RECTIFIER)

- VOLTAGE

+ VOLTAGE

FULL WA VE RECTIFIER

(BRIDGE RECTIFIER)

D.C. OUTPUT

The full wave rectifier mak es use of the entire A.C. signal, converting it to D.C.

COMPONENTS BATTERY

- VOLTAGE

A.C. INPUT

+ VOLTAGE

A.C. INPUT

+ VOLTAGE

(D.C.)

The batteries used in conjunction with Tecumseh engines are 12 volt lead acid or “maintenance free” style. The chemical energy produced by the dissimilar metals of the battery plates provides a electrical potential that is used to power the electric starter or unit accessories. Consult

- VOLTAGE

D.C. OUTPUT

the original equipment manufacturer’s service manual f or battery size, capacities, and testing procedure.

WIRING

The wires used in Tecumseh electr ical systems are copper stranded with an insulated coating around the copper strands.

CONDITION: All wiring must be fully insulated between connection points, securely fastened and free of foreign material (such as rust and corrosion) at the connection points. This is especially important in the use of batteries where much of the potential may be lost due to loose connections or corrosion. Remember to check the insulation on the wire. All it takes is a pin hole to "ground out" on the engine or frame. This is of special concern when moisture or water is present. This may cause the engine to run erratically or be impossible to start.

WIRE GAUGE: The proper thickness of wire is necessary

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in all electrical circuits. Wire diameter is measured in increments of gauge numbers. As the gauge number of the wire increases, the wire diameter decreases in size

THE LARGER THE NUMBER THE SMALLER THE WIRE

# 18

(diag.6).

1. The starter circuit wiring must be rated at #6 or lo wer gauge number.

# 6

2. The charging circuit wir ing must be rated at #16 or lower gauge number (20 amp system requires #14 or lower gauge number).

3. The magneto circuit wir ing (ground circuit) must be rated at #18 or lower gauge number.

Tecumseh's standard engine wiring color codes, effective August, 1992 are as follows:

Code Product

Yellow - Alternator A.C. Leads Red - Alternator D.C. + Leads Brown - Alter nator D.C. - Leads Black - Alternator Ground Leads, Battery Ground Leads Orange - 12 Volt Starter B + Leads Dark Green - Ignition Shut-Off Leads

NOTE: PRIOR TO AUGUST 1992, WIRE CODES CHANGED ACCORDING TO MODEL AND SPECIFICATION NUMBERS.

ELECTRICAL TERMS

AL TERNAT OR - An alternator consists of coils of wire

wound around a metal lamination stack. When a magnet is moved past the coils, a current is induced in the coils. In general, the greater the number of coils, the greater the output of the alternator (diag. 7).

IGNITION COIL - The ignition coil is used to fire the spark plug. It is completely independent from the alternator coils.

RECTIFIERS and DIODES - Charging a battery requires that the alternating current produced by the alternator be changed to direct current. This is accomplished by using a diode or rectifier.

REGULATOR/RECTIFIERS - This combines a regulator with a rectifier. The regulator prevents overcharging of the battery and the rectifier changes the alternating current to direct current (diag.8, 9, 10).

CONDUCTORS - A conductor is a material that allows an electric current to pass through it. All metals are conductors of electricity , but some are better conductors than others. Silv er, copper and gold are some of the better known conductors. As the temperature of the conductor increases, the resistance increases.

INSULATORS - An insulator is a material that will not allow an electric current to pass through it. Some of the more common materials that are insulators are glass, plastic, rubber, ceramics and porcelain.

BASIC CHECKS

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Before going into extensive checks, be sure to perform the more basic checks first, such as:

1. Battery defective or not charged.

2. Corroded or loose ter minals and connections, or wrong connections.

3. Cracked insulation or broken wires.

4. A wire "grounding out" in the system.

5. Defective switch.

6. Operator presence system functioning proper ly.* *NOTE: ALL LAWN AND GARDEN TRACTORS BUILT AFTER JULY OF 1987 ARE REQUIRED TO HAVE AN

OPERATOR PRESENCE SYSTEM AND MANY CAME EQUIPPED WITH SUCH A SYSTEM PRIOR T O THIS D ATE. IF THE TRACT OR IS "CUTTING OUT" OR WILL NOT START , THIS IS AN AREA THAT SHOULD BE CHECKED OUT.

TROUBLESHOO TING ELECTRICAL STARTER CIRCUIT FLOW CHART

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Repair or

replace power

source

Starter will not

turn

Is there power

at the power

source?

Check wiring,

connections,

safety switches,

starter switch

YES

Intermittent

starter operation

Is power supplied to the

starter terminal?

Starter turns at

stalls under load

YES

Isolate engine

from the

equipment,

does engine

turn over?

low rpms or

YES

Check starter for binding brushes,

worn brushes,

dirty or oily

commutator

Internal engine

failure or flywheel

interference

Remove spark

plug, does engine

turn over freely?

Repair or replace

electric starter

YES

Reinstall spark

plug, does

engine bind on

compression

stroke?

Repair or replace

equipment

causing

excessive loading

YES

Check valve lash.

necessary. Does

YES

Internal engine

failure, repair or

replace engine

the engine turn

over without

binding now?

Adjust if

TROUBLESHOO TING ELECTRICAL CHARGING CIRCUIT FLOW CHART

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Identify the charging system used by model and specification number or visually check the electrical plug

Consult the Technician's Handbook or Electrical Troubleshooting booklet for test procedure for the charging system used

T est f or either A C or DC voltage as directed at the proper engine RPM

Alternator coil failure, replace coil assy.

Is AC voltage before diode or rectifier greater than the minimum value?

Is the voltage greater than or equal to the minimum value?

YES

Check diodes,

replace if no

continuity exists or

if continuity exists

reversing test leads

Check fuses,

replace as necessary

YES

Check wiring, switches, or ammeter for breaks, shorts

Check switches,

wiring, or lights for

shorts

TESTING PROCEDURE

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STARTING CIRCUIT

1. Check the power source using an electrical tester and follow the testers recommended procedure. Mak e sure the battery meets the minimum battery voltage requirements found in the original equipment manufacturer's service manual.

2. Check the electric starter terminal for the required voltage (12v D.C. or 120 v A.C.) using a voltmeter.

CAUTION: FOLLOW ALL SAFETY PRECA UTIONS WHEN TESTING FOR A.C. V OL TAGE, ELECTRIC SHOCK CAN KILL.

3. Check wiring, connections, fuses, ignition or starter switch, safety switches, or solenoid for continuity using a ohmmeter or a continuity light. Repair or replace as necessary.

4. Remove all equipment loads from the engine. Take off all drive belts, chains, and couplers to isolate the engine from the equipment it is powering.

5. Try to turn the engine over using the recoil assembly if equipped. If the engine doesn’t turn over, a mechanical binding may be the cause. Chec k for proper lubrication (oil le vel and viscosity), starter gear and flywheel ring gear interference. If no problem is discovered, the problem is an internal failure.

6. If the engine binds only on the compression stroke, check the engine valve clearance per the specification table in Chapter 10. If the v alve clearance is within the specifications, the camshaft (compression release) may require replacement. Valve clearance not within the listed specifications will require either resetting or grinding the valve stems to obtain the proper clearance.

7. If the engine turns ov er freely, the electric starter should be disassembled and checked. If the preceding steps f ail to correct the problem, the engine will require disassembly to find the mechanical failure. See Chapter 9 under "Disassembly Procedure".

CHARGING CIRCUIT

The following pages will show wiring diagrams of several Tecumseh charging systems. The charging system used on the engine is best identified by obtaining the engine model number and the specification number on the engine. Consult a Tecumseh dealer or a parts manual to identify the charging system. To make many of the tests it is necessary to run the engine and measure alternator output with a voltmeter. When making v oltage tests with the engine running, it is not necessary to take readings at all the listed R.P.M.s. Checking at one of the speeds is sufficient.

In some cases an open circuit D.C. check cannot be made. An SCR (Silicon Controlled Rectifier) is located in the circuit which requires a minimum “turn on” voltage to allo w it to conduct. Without the battery in the circuit this “turn on” voltage is not present. The SCR “senses” this and there will be no D.C. output from the regulator or rectifier.

Each charging system has its own testing procedure. T est the charging system using the applicab le procedure on the following pages.

350 Milliamp Charging System

(+) POSITIVE LEAD

Models: TVS 75-90-100-105-115-120

CHECKING THE SYSTEM: The batter y must be in the

circuit to perform the test properly. Connect a voltmeter across the battery . The v oltmeter should read the battery voltage. Start the engine. With the engine running, there should be an increase in the voltage reading. If there is no change in the voltage reading, the alternator is defective and should be replaced. See Chapter 9 for "Disassembly Procedure" (diag. 11).

NOTE: SET THE VOLTMETER TO THE 0-20 VOLT D.C. SCALE FOR THE TEST.

MAGNETO GROUND

(GR)

BATTERY

GROUND (BL)

BLACK

(-) ENGINE GROUND

D.C. OUTPUT

LEAD (RED)

ELEC. STARTER

LEAD (ORG)

RED

18 Watt A.C. Lighting Alternator

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Models: H35, HS & HSSK 40-50, HM & HMSK 70-80-100

CHECKING THE SYSTEM: To check the system,

disconnect the plug from the rest of the lighting system. Connect a wire lead from the single pin connector coming out of the engine to one terminal of a No. 4414, 18 watt bulb. Connect another wire lead to the other terminal of the bulb and run to a good ground on the engine. Start the engine and test the circuit using the A.C. voltmeter as shown (diag. 12).

With the engine running, minimum A.C. voltage across the bulb should be:

2000 R.P.M. - 6.0 Volts A.C.

ENGINE

YELLOW

3000 R.P.M. - 8.5 Volts A.C. 3600 R.P.M. - 10.0 Volts A.C. If minimum values are noted, the alternator is okay. If

less than the minimum values, the alternator is defectiv e. See Chapter 9 for "Disassembly Procedure".

1 Amp (18 Watt) Add-on Alternator

CHECKING THE SYSTEM: To check the system,

disconnect the plug from the rest of the lighting system. Connect a No. 4414, 18 watt bulb in line with each terminal in the plug. Start the engine and test the circuit using a voltmeter as shown (diag. 13).

With the engine running, minimum A.C. voltage values across the bulb should be:

2000 R.P.M. - 8.0 Volts A.C. 3000 R.P.M. - 10.5 Volts A.C. 3600 R.P.M. - 12.0 Volts A.C. If minimum values are noted, the alternator is okay. If the

minimum values are not noted, the alternator or A.C. connector is defective. See Chapter 9 for "Disassembly Procedure".

#4414 BULB

YELLOW

#4414 BULB

YELLOW

D.C. Charging Adaptor

Rectifier Bridge Check With Ohmmeter for D.C. Adaptor

The following tests should be performed without the engine running to determine the condition of the D.C. adaptor.

Continuity should exist during one of the two following tests. No continuity should exist while performing the opposite test.

If continuity exists during both tests, or if no continuity exists during both tests, the D.C. adaptor is defective.

TEST NO. 1 - Connect negative probe of meter to red output lead. Connect positiv e probe of meter to both A.C. terminals and black output lead (diag. 14).

BLACK

A.C. TERMINALS

(continued on top of next page)

BLACK

RED

OUTPUT LEADS

RED

#4414

BULB

TEST NO. 2 - Connect the positive probe of meter to red output lead. Connect the negativ e probe of meter to both A.C.

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terminals and black output lead. Connect the negative probe of meter to black output lead. Connect the positive probe of meter to both A.C. terminals

and red output lead. If the D.C. adaptor is not defective and a known good battery fails to hold a charge, then perform an A.C. output

voltage test.

NOTE: PRIOR TO AUGUST 1992, THE BLACK WIRE WAS BROWN. CHECKING THE SYSTEM: To check the system, disconnect the D.C. adaptor from the add-on alternator. Connect a

No. 4414, 18 watt bulb in line with each terminal in the alternator. Start engine and test circuit using an A.C. voltmeter as shown (diag 14).

With the engine running, minimum A.C. voltage values across the bulb should be: 2000 R.P.M. - 8.0 Volts A.C. 3000 R.P.M. - 10.5 Volts A.C. 3600 R.P.M. - 12.0 Volts A.C. If the minimum values are noted, alternator is okay. If the minimum values are not noted, the alternator or A.C.

connector is defective.

2.5 Amp D.C., 35 Watt Lighting

To check this system follow the meter hook ups at the right, checking the D .C . negative and D.C . positiv e first. If output is below standard listed, pull back protective coating in front of the diode and check A.C. output. If A.C . is good check each diode it services as requested see parts list. (diag. 15)

D.C. value (+) or (-) check. A.C. outputs both sides. R.P.M. D.C . Volts R.P.M. Volts A.C.

2500 - 8.0 Volts D.C . 2500 - 18 Volts A.C. 3000- 9.5 V olts D .C . 3000 - 22 Volts A.C . 3300- 10.5 Volts D .C . 3600 - 26 Volts A.C. 3600- 11.5 Volts D . C.

NOTE: These minimum numbers should be obtained by your meter and will often be higher.

3 Amp A.C. Lighting Alternator Models: H & HSK 30- 35, HS & HSSK 40, H & HSK 50-60, HH50-60, HM & HMSK 70-80-100, HHM80

Before making any e xterior tests, check for an inoper ative switch, shorted wires and burned out headlight and/or stop tail light. To check out the alternator, check the A.C. lead to ground (diag. 16).

TWO DIODES

A.C.

HEAD & TAIL LIGHT

RED

D.C.

YELLOW

TO POSITIVE SIDE OF BATTERY

D.C. NEGATIVE OUTPUT LEAD (BROWN D.C.)

D.C. POSITIVE OUTPUT LEAD (RED D.C.)

With engine running, minimum values should read:

2500 R.P.M. - 8.0 Volts A.C. 3000 R.P.M. - 9.5 Volts A.C. 3300 R.P.M. - 10.5 Volts A.C. 3600 R.P.M. - 11.5 Volts A.C.

If the above minimum readings are noted, the alternator is okay. Check for defective lights, wiring or switches. If less than the above readings, the alternator is defectiv e. See Chapter 9 for "Disassembly Procedure".

GREEN

YELLOW

IGNITION GROUND

STOP LIGHT

NOTE: ON OLDER POINT IGNITION SYSTEMS, THE

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A.C. OUTPUT LEADS ARE BLACK AND RED.

3 Amp D.C. Alternator System - Rectifier Panel

This 3 amp system is readily identified by the rectifier panel in the circuit. The panel includes two diodes and a fuse for overload protection. The rectifier panel does not regulate the output of this system.

CHECKING THE SYSTEM: Check the fuse to determine if it is good. A continuity light or ohmmeter can detect a faulty fuse. Replace with a six (6) amp fuse if necessary. Determine if the diodes are functioning properly. A continuity light may be used to check diodes. (diag. 17).

GREEN

YELLOW

D.C. VOLTMETER

YELLOW

When replacing the diode in the rectifier panel, locate the undercut on one end of the diode and match it to the detent on terminal clip of the rectifier panel.

Test the D.C. output of the rectifier panel as follows: Disconnect the battery lead from the terminal of rectifier

panel. Use D .C . voltage meter probe on + battery terminal as shown in the diagram (diag. 18). Connect negative lead to engine ground.

Minimum values should read: 2500 R.P.M. - 12.0 Volts D.C. 3000 R.P.M. - 14.0 Volts D.C. 3300 R.P.M. - 16.0 Volts D.C. 3600 R.P.M. - 18.0 Volts D.C. If these minimum readings are noted, the system is okay.

Check for bad battery, ammeter, wiring, etc. If less than above reading, proceed to make an A.C . output

check. With the battery lead disconnected from rectifier panel, probe the A.C. terminals with the voltmeter on the A.C. scale (diag. 19).

Minimum values should read:

PROBE

FUSE

RECTIFIER PANEL

MOUNTED ON

ENGINE

FUSE

TO ENGINE

GROUND

VOLTMETER

A.C.

2500 R.P.M. - 24.0 Volts A.C. 3000 R.P.M. - 29.0 Volts A.C. 3300 R.P.M. - 32.0 Volts A.C. 3600 R.P.M. - 35.0 Volts A.C. If less than above output, generating coil assembly is

defective. See Chapter 9 for "Disassembly Procedure". NOTE: There is no regulator in this system. The total

output of the two diodes is three (3) AMPS. If the battery is overcharging (boiling and bubbling), reduce the D.C. input by one-half by removing one of the diodes.

3 Amp DC Alternator System - Diode in

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Harness Sleeve Models: H30-35, HS40, H50-60, HH50-60, HM70-80-100, HHM80

This system has a diode included in the red wire which converts the alternating current (A.C.) to direct current. The direct current (D .C.) is used to provide a trickle charge for the battery . The leads from the alternator and the type of connector may vary, but the output readings will be the same.

CHECKING THE SYSTEM: Remove the fuse from the fuse holder and check the fuse to make certain it is good. If faulty, replace with a six (6) AMP fuse.

To check D.C. output, separate the connectors at the engine. Place the probe (+) in the red wire lead connector . Ground the other probe to the engine (diag. 20).

With the engine running minimum values should read: 2500 R.P.M. - 8.0 Volts D.C.

GREEN

RED

GROUND

PROBE (+)

DIODE

3000 R.P.M. - 9.5 Volts D.C. 3300 R.P.M. -10.5 Volts D.C. 3600 R.P.M. -11.5 Volts D.C. If these minimum readings are noted, the system is okay.

Check for bad battery, ammeter, wiring, etc. If less than the above readings , proceed to make an A.C.

output check by pulling back the protective coating from the fuse holder and diode. Using an A.C. voltmeter , check voltage from a point between the engine and the diode as shown in the diagram (diag. 21).

With the engine running, minimum values should read: 2500 R.P.M. - 18.0 Volts A.C. 3000 R.P.M. - 22.0 Volts A.C. 3300 R.P.M. - 24.0 Volts A.C. 3600 R.P.M. - 26.0 Volts A.C. If low or no voltage is e xperienced, replace the alternator.

If the alternator puts out the minimum A.C. voltage, replace the diode.

T o replace the diode , disconnect at plug (spade terminal) and cut the wire on the opposite end of the diode at the solderless (crimped) connector. Remove 1/4" (6.35 mm) of insulation from the cut end of the wire and twist the strands together. Place the solderless connector from the new diode onto the exposed 1/4" (6.35 mm) wire and crimp the connector with a standard electricians pliers. Reconnect plug end (or spade connector (diag. 22).

PROBE (+)

GROUND

SOLDERLESS CONNECTOR

FUSE HOLDER

RED

GREEN

SPADE CONNECTOR

5 Amp Alternator System Regulator-Rectifier

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Under Blower Housing

CHECKING THE SYSTEM: An open circuit D. C. voltage

check cannot be made with this system. If a known good battery fails to maintain a charge, proceed to make an A.C. voltage test.

To do this, the blower housing must be remov ed, and the regulator-rectifier must be brought outside of the blower housing.

Disconnect the red D.C. output connector at the wiring harness and connect the probes from an A.C. voltmeter to the wire terminals at the regulator-rectifier (diag. 23).

INSERT PROBES INTO CONNECTOR SLOTS. DO NOT REMOVE CONNECTOR WIRES.

A.C. VOL TMETER

CAUTION: A T NO TIME SHOULD THE ENGINE BE STARTED WITH THE BLOWER HOUSING REMOVED.

CAUTION: BLOWER HOUSING MUST BE INST ALLED WHEN RUNNING ENGINE

With the engine running, the minimum values should read: 2500 R.P.M. - 19.0 Volts A.C. 3000 R.P.M. - 23.0 Volts A.C. 3300 R.P.M. - 26.0 Volts A.C. 3600 R.P.M. - 28.0 Volts A.C. If the minimum values are noted, the alternator is okay; the regulator-rectifier is def ectiv e. If less than above readings,

the alternator is defective. See Chapter 9 for "Disassembly Procedure".

3 Amp D.C. 5 Amp A.C. Alternator Models: H & HSK 50-60, HH50-60, HM & HMSK 70-80-90-100, TVM125-140-170-195-220,

TVXL195-220

This unit combines a 3 Amp D .C. system used to charge a battery with a 5 Amp A.C. system used for lighting. Located in the red wire of the harness is a diode which converts the alternating current to direct current for charging the battery. The yellow wire provides the A.C. voltage for the lighting circuit.

RED

DIODE

YELLOW

D.C .

(continued on top of next page)

CHECKING THE SYSTEM: To check the system,

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disconnect the plug and measure the D.C. voltage at the red wire terminal (diag. 24). Measure the A.C. voltage at the yellow wire terminal. With the engine running, the minimum values should be:

3 Amp D.C.

2500 R.P.M. - 8.0 Volts D.C. 3000 R.P.M. - 11.0 Volts D.C. 3600 R.P.M. - 13.0 Volts D.C.

5 Amp A.C.

RED

2500 R.P.M. - 8.0 Volts A.C. 3000 R.P.M. - 11.0 Volts A.C. 3600 R.P.M. - 13.0 Volts A.C.

If the above minimum values are noted, system is okay. Check for def ectiv e lights , wiring or switches. If less than above values are noted, pull back the protective shrink tubing from the diode. Using an A.C. voltmeter, chec k the voltage going into the diode from alternator, at the lead on the alternator side of the diode (diag.25).

All Models

With the engine running, the minimum values should read: 2500 R.P.M. - 20.0 Volts A.C. 3000 R.P.M. - 25.0 Volts A.C. 3300 R.P.M. - 26.5 Volts A.C. 3600 R.P.M. - 29.0 Volts A.C. If low or no voltage is e xperienced, replace the alternator. If the alternator puts out the minimum A.C. voltage, replace the diode.

7 Amp Alternator System Regulator-Rectifier External to Engine

A.C.

YELLOW

D.C. VOLTMETER

B + TERMINAL WIRE

REGULATOR/RECTIFIER

MUST BE GROUNDED

CHECKING THE SYSTEM: To check the system, disconnect the D.C. or B+ wire at the switch end and measure D .C. voltage between the lead and ground (diag.

26).

With the engine running, minimum values should read: 2500 R.P.M. - 9.0 Volts D.C. 3000 R.P.M. - 11.0 Volts D.C. 3600 R.P.M. - 14.0 Volts D.C.

If the minimum readings are noted, system is okay. Chec k for defective ammeter, wiring, etc. If less than the above readings, disconnect the plug from the regulator-rectifier, and insert the A.C. voltmeter probes in the two outside terminals (diag. 27).

With the engine running, minimum values should read: 2500 R.P.M. - 12.0 Volts A.C. 3000 R.P.M. - 14.0 Volts A.C. 3600 R.P.M. - 18.0 Volts A.C.

If the minimum readings are noted, the alternator is okay; the regulator-rectifier is defective. If less than the above readings, the alternator is defective. See Chapter 9 for "Disassembly Procedure".

A.C.

7 Amp Alternator System Regulator-

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Rectifier Under Engine Block Housing Models: H50-60, HH50-60, HM70-80-100, HHM80, TVM125-140-170-195-220

In this system, the regulator and rectifier are combined in one solid state unit mounted under the blower housing of the engine.

Various types of regulator-rectifiers have been used on different applications. Test procedures for all types are the same. However, regulator styles are not interchangeable (diag. 28).

CHECKING THE SYSTEM: An open circuit D. C. voltage check cannot be made with this system. If a known good battery fails to maintain a charge, proceed to make an A.C. voltage test.

To do this, the blower housing must be remov ed, and the regulator-rectifier must be brought outside of the blower housing. Keep the A.C. leads attached to the regulator-rectifier. Install the blower housing with the regulator-rectifier outside the housing. With an A.C. voltmeter probe the regulator as shown (diag. 29)

CAUTION: A T NO TIME SHOULD THE ENGINE BE STARTED WITH THE BLOWER HOUSING REMOVED.

With engine running, minimum A.C. voltage from lead to lead should be:

2500 R.P.M. - 16.0 Volts A.C. 3000 R.P.M. - 19.0 Volts A.C. 3300 R.P.M. - 21.0 Volts A.C. 3600 R.P.M. - 23.0 Volts A.C.

If the minimum readings are noted, the alternator is okay . If the system fails to charge a known good battery, the regulator-rectifier must be defective.

MAGNETO GROUND - GREEN

CAUTION: BLOWER

HOUSING MUST BE

INSTALLED WHEN

RUNNING ENGINE

B+ TERMINAL WIRE

D.C. OUTPUT LEAD-RED

INSERT PROBES INTO

CONNECTOR SLOTS

DO NOT REMOVE

CONNECTOR WIRES

YELLOW

RED

A.C. VOLTMETER

10 Amp Alternator System - RegulatorRectifier-External to Engine

In this system, the regulator and rectifier are combined in one solid state unit.

CHECKING THE SYSTEM: To check the system, disconnect the D.C. or B+ wire at the switch end and measure D .C. voltage between the lead and ground (diag.

30). With the engine running, minimum values should read: 2500 R.P.M. - 13.0 Volts D.C.

3000 R.P.M. - 16.0 Volts D.C. 3600 R.P.M. - 20.0 Volts D.C.

If the minimum values are noted, the system is okay. Check for def ective ammeter, wiring, etc. If less than the above readings, disconnect the plug from the regulatorrectifier, and insert the A.C. voltmeter probes in the two outside terminals (diag. 31).

GREEN

(continued on top of next page)

YELLOW

REGULATOR/

RECTIFIER MUST BE

GROUNDED

With the engine running, minimum values should read:

Main Menu

2500 R.P.M. - 16.0 Volts A.C. 3000 R.P.M. - 19.0 Volts A.C. 3600 R.P.M. - 24.0 Volts A.C. If the minimum readings are noted, the alternator is okay;

the regulator-rectifier is defective. If less than above readings, the alternator is defective. See Chapter 9 for "Disassembly Procedure".

A.C. OUTPUT

YELLOW

A.C.

10 Amp Alternator Models: H & HSK 50-60, HH50-60, HM & HMSK 70-80-100, HHM80, TVM125-140-170-195-220

CHECKING THE SYSTEM: Unplug the connector at the wiring harness supplied by the OEM. Proceed to make an

A.C. output check. Place one lead of the A.C. voltmeter on the center plug of the connector. Place the other lead to engine ground (diag. 32).

With the engine running, minimum values should read: 2500 R.P.M. - 16.0 Volts A.C. 3000 R.P.M. - 20.0 Volts A.C. 3300 R.P.M. - 22.0 Volts A.C. If less than above output, the alternator assembly is defective. See Chapter 9 for "Disassembly Procedure".

VOLTAGE REGULATORS

If a known good or load tested battery fails to maintain a charge, the charging system and the regulator can be checked using a voltmeter. Set the voltmeter on the 0-20 Volt D.C. scale and connect the probes across the battery terminals as shown. Note the battery voltage. Star t the engine, the voltage reading should increase from the noted battery voltage but not exceed 15 Volts D.C. If no voltage increase is noted, proceed to make an A.C. voltage check using the applicable procedure. If the batter y voltage exceeds 15 Volts D.C., or the proper minimum A.C. voltage is noted during the check, replace the regulator.

LOW OIL SHUTDOWN SWITCHES

Check the LOS switch while it is in the engine. The engine must be level, and the oil level at the full mark. Place the speed control in the run position. Remo ve the spark plug wire from the spark plug. Install a gap type tester connected to the spark plug wire and a good engine ground. Spin the engine ov er using the electric or recoil starter. A bright b lue spark should be seen at the tester. If not, remove the blower housing and disconnect the LOS lead from the ignition module. Reinstall the blower housing and spin the engine over. If spar k occurs now, replace the LOS switch. If no spark is seen, replace the ignition module.

ON/OFF LIGHTED ROCKER SWITCH W/LO W OIL SHUTDOWN

SER VICE

Main Menu

This section covers the service procedures for the 12 and 120 v olt electric starters. For diagnosis of the starting circuit see “Electrical Starter Troubleshooting” in this chapter. Illustrations may not be identical in configur ation to the starter being serviced, but procedures and tests apply unless otherwise stated.

12 V OL T OR 120 V OL T ELECTRIC ST ARTERS WITH EXPOSED SHAFT

1. Remove the plastic dust cover on the armature end (diag. 34).

2. Push down the spring retainer and remove the retainer ring.

3. Slide off the spring retainer, anti-dr ift spring, gear, and drive nut.

4. If inter nal ser vice is necessary, scribe a line across the cap assemblies and armature housing to aid in reassembly.

5. Remove the two or four retaining nuts from the through bolts holding the cap assembly.

6. Slide off the cap assembly. The ter minal insulator slides out of the commutator cap.

7. Remove the armature.

8. Inspect and replace as necessar y.

9. Use the reverse procedure for reassembly.

10. Inspect flywheel ring gear for damage before

installation.

12 VOLT D.C. OR 120 VOLT A.C. ELECTRIC STARTERS WITH CAP ASSEMBLY

1. Remove the retainer ring from the armature shaft (diag.35).

2. Remove the two nuts from the through bolts holding the cap assembly on.

3. Slide off the cap assembly. The engaging nut, gear, spring, and spring retainer will remain in the cap assembly.

4. If complete disassembly is required, refer to step # 4 in the previous section for additional steps.

5. Inspect and replace as necessary. Use reverse procedure for assembly. ( F or ease of assembly , place the armature into the brush end frame first.)

6. Inspect flywheel ring gear for damage before

installation.

GEAR

DRIVE NUT

SPRING

RETAINER

RING

CAP ASSY.

ARMATURE

(continued on top of next page)

INSPECTION AND REPAIR

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1. The pinion gear parts should be checked f or damage or wear. If the gear does not engage or slips , it should be washed in solvent ( rubber parts cleaned in soap and water) to remove dirt and grease, and dried before reassembly. Also check the armature and drive nut splines for wear or damage. Replace par ts as necessary.

2. The brushes and brush card holder should be checked f or wear . With the armature in place and the brushes engaging the commutator surface, chec k the brushes for wear. Brushes should be replaced if the brush wire approaches the bottom of the brush holder slot. Brush springs must exhibit enough strength to keep tension on the brushes and hold them on the commutator.

3. The field windings can be checked using a continuity light or ohmmeter. Attach one lead to each field coil connection. Continuity should exist between each field coil connection, and no continuity should exist between the field coil connections and the starter housing (diag. 36 & 37).

4. The armature should be check ed for glazing or wear . If necessary the ar mature can be turned down in a lathe. While rotating, polish the commutator bars using a piece of 00 sandpaper (diag. 38). Light pressure and back and forth movement should be used. Recut the comm utator bars to a depth equal to the width of the insulators between the bars. Check for continuity between the copper commutator bars and the iron of the armature, none should exist (diag.

39). If any is noted the armature must be replaced.

FIELD COIL

CONNECTORS

BRUSH

SPRINGS

12 VOL T

FIELD COIL

CONNECTORS

CONNECTION POINT OF

POWER CORD LEADS

120 VOLT

38 39

Brush Card Replacement

1. Loosen but do not remove the two nuts on the starter terminal post.

2. Remove the nuts holding the end cap in place. Remove the end cap and the thrust washer.

3. Grasp the thru bolts using a vise gr ip positioned as close to the flanged end as possible to prevent thread damage. Remove the two nuts holding the driving end cap in place. Remove the armature and driving cap assembly, followed by the two thru bolts. Notice the position of the brush ground eyelet under the thru bolt flange.

4. Note or mar k the position of the connectors of the brush wires. Use a wire cutter to clip the solid field wires as close to the connectors as possible.

5. Note or mark the brush card in the starter housing and remove the brush card assembly. Clean the accumulated dirt off all starter parts. Scrape the insulating varnish off the last 1/2" (12.7 mm) of the solid field wires.

6. Inser t the new brush card into position while guiding the solid field wires through the proper slots in the brush card.

7. Crimp and solder the brush leads to the solid field wires. Use a needle nose pliers or vise grip to hold the woven brush lead close to the connector while soldering. This prevents solder and heat from flowing up the brush lead. Insulate the crimped connection nearest the starter ter minal post using electrical tape or heat shrink tubing. Route the wires to prevent damage during assembly.

8. Install the ar mature into the housing while spreading the brushes. Install the thru bolts while checking to make sure the bolts go thru the ground brush eyelet terminals. Install and tighten the drive end thru bolt nuts, b ut do not overtighten.

9. Install the thrust washer (cupped side faces towards the end cap) on the end of the armature and then install the starter end cap. Secure the cap with the locking nuts and tighten the nut on the starter terminal post. Rotate the armature by hand to check for binding before installation on the engine.

CHAPTER 7 FLYWHEEL BRAKE SYSTEMS

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GENERAL INFORMATION

Tecumseh’s brake systems provide two methods of meeting compliance standards which has become a federal law as of June 30, 1982. There are two additional methods used by equipment manufacturers that also meet compliance standards and they are as follows:

1. Use of the blade brake clutch in conjunction with either a top or side mounted recoil starter or 12 volt electric starter. The blade stops within three seconds after the operator lets go of the blade control bail at the operator position and the engine continues to run. Starter rope handle is either on the engine or on the equipment handle.

2. Use of a recoil starter (top or side mounted) with the rope handle on the engine as opposed to within 24 inches (60.9 cm) of the operator position. This method is acceptable if the mower deck passes the 360 degree foot probe test. A specified foot probe must not contact the blade when applied completely around the entire blade housing. This alternative can be used with engine mounted brake systems and typical bail controls. The b lade stops within three seconds after the operator lets go of the engine/blade control bail at the operator position and the engine is stopped.

Tecumseh’s Flywheel Brake system provides consumer safety by stopping the engine and blade within three seconds after the operator releases the engine/blade control bail at the handle of the lawnmower. These systems are available on both recoil and electric start models. The engine stopping time is affected by the engine R.P.M. Consult microfiche card #30, the Plus 1 or Parts Smart Look-Up system, or Service Bulletin #107 to determine the correct engine speed or blade tip speed.

OPERATION

BOTTOM SURFACE SYSTEM

In the stop position with the handle mounted engine / blade control released, the torsion spring rotates the brake lever forcing the brake pad against the underside of the flywheel, actuates the ignition kill switch and on electric start models, opens the star ter inter lock switch (diag. 1).

In order to restart the engine, the handle mounted engine / blade control must be applied. This action pulls the brake pad away from the flywheel, opens the ignition kill switch and on electric start models, closes the starter interlock switch. This will allow the engine to be started by energizing the starter with a starter switch (diag. 2).

BRAKE

APPLIED

IGNITION

SHORTED

BRAKE

RELEASED

IGNITION

OPEN

INTER-LOCK

SWITCH OPEN

INTER-LOCK

SWITCH CLOSED

OPERATION (CONTINUED)

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INSIDE EDGE SYSTEM

In the stop position the brake pad is applied to the inside edge of the flywheel, at the same time the ignition system is grounded (diag. 3).

In order to restart the engine, the brake control must be applied. This action pulls the brake pad away from the inside edge of the flywheel and opens the ignition kill switch. On electric start systems the starter is energized by an ignition switch or a two motion control. On non-electric start systems, the recoil starter rope must be pulled to start engine (diag. 4).

IGNITION SHORTED

BRAKE APPLIED

COMPONENTS

Both the Bottom Surface and the Inside Edge systems use the following components:

The brake lever and pad assembly consists of a steel lever with a brake pad bonded to the lever (diag. 5).

The ignition kill switch is a plastic block with a wire extending out of it. The wire is attached to a terminal which is connected to the ignition kill wire. The brake lever contacts and g rounds the wire of the switch when the engine / blade control is released, and the ignition module is grounded. This in turn kills the ignition (diag.

5).

The interlock switch is a push button switch that is activated by the brake lever when the engine / blade control is actuated. If there is a starter switch used to start the engine, the interlock switch acts as a safety switch and will not allow the starter to crank unless the engine / blade control is depressed.

BRAKE LEVER

IGNITION KILL

CONTROL CABLE

IGNITION OPEN

AND PAD

SWITCH

INTERLOCK

SWITCH

BRAKE RELEASED

TORSION

SPRING

Where a two motion control is used the interlock switch is utilized as the starter switch.

The Torsion Spring supplies the pressure to the brake lever and brake pad to stop the flywheel.

The Control Cable transfers the motion of the engine / blade control to the brake system.

SERVICE

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If the brake system fails to kill the ignition and stop the blade within 3 seconds the following service procedures should be followed.

FLYWHEEL REMOVAL

NOTE: BEFORE THE FLYWHEEL IS REMOVED OR REPLACED, THE BRAKE PRESSURE ON THE FLYWHEEL

MUST BE RELIEVED AS OUTLINED BELOW UNDER "BRAKE LEVER AND PAD". Remove the flywheel as outlined in Chapter 9 under "Disassembly".

BRAKE LEVER AND PAD Bottom Surface

To relieve the brake pressure on the flywheel, remove the torsion spring by firmly grasping the short end of the spring with a pliers and unhook the spring from the bracket then remove the flywheel (diag. 6).

Remove the brake lever and pad assembly. Inspect the brake pad for dirt, oil or grease contamination. If the pad is contaminated, or if there is less than .060" (1.524 mm) of brake pad material at the pad's thinnest point, replacement is necessary. The brake pad is bonded to the brake lever and must be replaced as an assembly. Install the brake lever and pad assembly and continue to reassemble the brake system in the reverse order of disassembly.

NOTE: WHEN REMOVING THE BRAKE BRACKET THE TORSION SPRING MUST BE RELEASED BEFORE THE TOP STARTER BOLT IS REMOVED OR THE THREADS IN THE CYLINDER BLOCK WILL BE DAMAGED.

Inside Edge

SWITCH

LEVER

UNHOOK TORSION SPRING

SHORT END OF SPRING

ALIGN HOLES

670298

T o relie ve the brak e pressure on the flywheel, compress the spring by moving the lever toward the spark plug, when the hole in the lever aligns with the hole in the bracket, secure the lever with alignment tool 670298 then remove the flywheel (diag. 7). Remove the alignment tool. Release the spring tension by unhooking the short end of the spring from bracket with a pliers. Remove the “E” clip from the brake pad shaft. Slide the pad lever from the shaft and unhook the link. Inspect the brake pad for dirt, oil or grease contamination. If the pad is contaminated, or if there is less than .060" (1.524 mm) of brake pad material at the pad's thinnest point, replacement is necessary. The brake pad is bonded to the brake lever and must be replaced as an assembly. Rehook the link, install the brake lev er and pad assembly , install the "E" clip, rehook the short end of the spring and continue to reassemble the brake system in the reverse order of disassembly.

IGNITION GROUNDOUT TERMINAL

Inspect the ignition kill switch grounding clip for proper alignment and contact with the brake arm. Insure that all electrical connections are clean and secure (diag. 8 & 9).

"E" CLIP

GROUNDING CLIP

GROUNDING CLIP POSITION

LINKAGE

BRAKE PAD

STARTER INTERLOCK SWITCH

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The engine / blade control must close the interlock s witch before the starter can be engaged. T o chec k the interlock switch, use an ohmmeter or continuity light to perform a continuity check. Continuity should exist between the two terminals when the interlock switch button is completely depressed. No continuity should e xist when the button is released. If the switch fails replace the switch (diag. 10).

T o replace the interlock s witch, carefully grind the heads off of the rivets that fasten the interlock switch to the brake bracket. Remove the rivets from the back side of brake brack et. Use the self-tapping scre w supplied with the new switch to make threads in the bracket. Install the interlock switch onto the brake br acket in the proper position and secure the switch to the brake brac ket with the machine screws supplied. Be careful not to overtighten the screws as switch breakage can occur (diag. 11).

CONTROL CABLE Bottom Surface

The control cable conduit must be assembled against the stop in the bracket. Make sure the bottom of the lever completely depresses the button on the starter interlock switch, if equipped, when the control is fully applied. The cable must provide enough travel so the brake will contact the flywheel. Some slack should exist in the cable adjustment to compensate for brake pad wear (diag. 12).

SELF TAPPING

SCREW

MACHINE

SCREWS

STOP

Inside Edge

If replacing the cable conduit screw with a screw other than a service part replacement, be cer tain that the screw length is not too long as to prevent free travel of the lever. Make sure the button on the starter interlock switch is completely depressed when the control is fully applied. The cable must provide enough travel so the brake will contact the flywheel. Some slack should exist in the cable adjustment to compensate for brake pad wear (diag. 13).

BRAKE BRACKET REPLACEMENT

The spring tension must be relieved on a bottom surf ace system prior to the removal of the top electric starter bolt, or damage to the threads in the cylinder block can occur.

When installing a inside edge brake bracket assembly, be sure the slotted holes in the brake bracket are all the way down on the fasteners. This will properly align the brake bracket to the flywheel brake surface (diag.

14).

SCREW END MUST

NOT BLOCK LEVER

ACTION

MOUNTING HOLES

MECHANISM FULL DOWN

BEFORE SCREWS TORQUED

CABLE CLAMP

SCREW

CHAPTER 8 IGNITION

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GENERAL INFORMATION

The ignition systems used on Tecumseh engines are either solid state capacitor discharge modules or magneto ignition systems. The basic functional difference is that the solid state modules are triggered by an electronic switch (SCR). Magneto ignition systems rely on the mechanical action of opening and closing a set of moveable contact points to trigger when the spark will occur.

The solid state ignition system consists of a flywheel magnet and key, charge coil, capacitor, a silicon controlled rectifier, pulse transformer, trigger coil, high tension lead, and a spark plug. Everything except the flywheel magnet, key and the spark plug are located in a encapsulated ignition module. This solid state (CDI - Capacitive Discharge Igntion) module is protected by epoxy filler from e xposure to dirt and moisture. This system requires no maintenance other than checks of the high tension lead and spark plug.

The Tecumseh magneto ignition consists of a stator assembly made of laminations, a coil, contact points, condenser, a permanent magnet mounted in the flywheel, high tension lead, and a spark plug. The coil is sealed by epoxy filler, and the points and condenser are sealed from dirt and moisture by a crankshaft seal and cover gasket.

OPERATION

SOLID STATE IGNITION SYSTEM (CDI)

As the magnets in the flywheel rotate past the charge coil, electrical energy is produced in the module. The energy is stored in the capacitor ( approx. 200 v olts) until it is released by an electrical switch (SCR). As the magnet continues to rotate, it travels past a trigger coil where a low voltage signal is produced. This low voltage signal closes the SCR switch, allowing the energy stored in the capacitor to flow to a transformer where the voltage is increased from 200 volts at 200 RPM to 22,000 volts at 3000 RPM. This voltage flows through the high tension lead to the spark plug where it arcs across the electrodes and ignites the air-fuel mixture (diag. 1).

MAGNETO IGNITION SYSTEM (POINTS)

As the flywheel turns, the magnets that are mounted in the wheelpass the coil mounted on the stator. As the magnet's North Pole enters the area of the center leg of the stator, a magnetic field is concentrated through the laminations to the magnet's South Pole. This causes a generation of current flow in the coil's primary winding. The ignition points are closed (diag. 2).

As the flywheel continues to rotate, the North Pole approaches the last leg of the lamination stack. The magnetic field through the center leg reverses , producing a large change in the magnetic field, and a high current in the primary side of the coil (diag. 3).

At this time, the contacts open and the primary current stops flowing. This change in current causes a v oltage in the primary, which induces a high voltage in the secondary winding of the coil. The voltage tra vels through the spark plug wire, to the spark plug and jumps the gap of the plug to ignite the air/fuel mixture.

PATH OF MAGNETIC LINES OF FORCE

MAGNET

FLYWHEEL ROTA TION

POINTS CLOSED

POINTS OPEN

IDENTIFICATION OF TECUMSEH IGNITION SYSTEMS

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INTERNAL IGNITION

SOLID STATE IGNITION (CDI)

EXTERNAL IGNITION

COMPONENTS OF A TECUMSEH MA GNETO IGNITION SYSTEM (DIAG. 7)

A. Flywheel with magnets B. Coil C. Condenser D. Spark plug E. Contact points F. Ignition cam G. Stator plate (dust cover , cam wiper, and laminations .) H. Flywheel key The flywheel with magnets provide the magnetic flux

(or field) which is necessary to induce the low voltage in the primary circuit. A horseshoe magnet is a good example of how the magnets function in the flywheel. The magnets are either cast in or glued onto the flywheel, and are not a replaceable item (diag. 8).

The ignition coil is used to increase the low voltage in the primary to high voltage in the secondary, capable of jumping the spark plug gap. The coil consists of a primary and a secondary winding of wire. The primary is the low voltage (200 - 300 volts) winding, consisting of approximately 150 turns of heavy gauge wire next to the core. The secondary winding consists of approximately 10,000 turns of very fine wire wrapped over the primary. When induced by the primary, the secondary winding generates a voltage of between 10,000 - 20,000 volts, which can arc the spark plug gap (diag. 9).

A. FLYWHEEL WITH

MAGNETS

D. SPARK PLUG

GROUND LEAD

PRIMARY LEAD

B. COIL

E. CONTACT POINTS

F. IGNITION CAM

PRIMARY WINDING

SECONDARY WIRING

HIGH TENSION LEAD

C. CONDENSER

G. STATOR PLATE

H. FLYWHEEL KEY

The condenser acts as an electrical shock absorber to

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prevent arcing betw een the contact points as they open. Arcing will lower the voltage at the spark plug, as well as burn and pit the contact points. The condenser is a replaceable item (diag. 10).

The spark plug is made up of two electrodes. The outside electrode is grounded and secured to the threaded sleeve. The center electrode is insulated with porcelain. The two are separated by an air gap which creates a resistance. A large voltage from the secondary arcs the air gap which causes a spark and ignites the air-fuel mixture in the cylinder (diag. 11).

The contact points consist of an insulated, movable point that connects to the coil primary lead, and a stationar y point that is grounded to the stator body. Spring tension holds the points together making a complete path for the primary circuit, and are opened by the action of the point arm which rests on the ignition cam. The contact points are a replaceable item (diag. 12).

The ignition cam is an oblong device which rotates with the crankshaft, and opens the points for firing the ignition system. It is important to check the ignition cam for roughness, if rough replace the cam. When inserting the ignition cam onto the crankshaft make sure that the side stamped "TOP", or the side that has an arrow on it f aces the mechanic (diag. 13).

NOTE: SOME IGNITION CAMS ARE MACHINED DIRECTLY ONTO THE CRANKSHAFT AND ARE NOT REPLACEABLE.

The stator plate is an aluminum fixture which houses the points, cam wiper, condenser , and has the laminations riveted to it. The laminations are strips of iron riveted together to form an iron core. Rust or debris in between the laminations will hamper the performance of the ignition system. If corrosion on the laminations is se vere, the stator plate should be replaced (diag. 14).

The flywheel key locates the flywheel to the crankshaft in the proper position. If a flywheel key is sheared, or partially sheared, the engine will not star t or be difficult to start (diag. 15).

IGNITION TROUBLESHOOTING

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Spark

Check flywheel for

damaged or sheared key

Set proper air gap on

external coil

Set proper point gap, check

condensor and timing

Engine Will

Not Start

Check for spark

Equipment problem,

check switches, wiring

and equipment controls

Spark

Engine runs

erratically or shuts

off, restarts

No Spark

Replace spark plug

Isolate engine and repeat

test

No Spark

Engine problem, check

for shorts or grounds in

wiring

Test

coil for intermittent or

weak spark

Check electric starter and

battery if applicable

Parasitic load

Disconnect ignition

cut-off wire

at the ignition coil &

repeat test

Oil shutdown or

on/off rocker switch

Check for proper air gap

on external

coil and repeat test

Check flywheel magnets

for strength

Test ignition module

TESTING PROCEDURE

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1. Check for spark using a commercially available spark tester and following the tester's recommended procedure.

2. Check for the correct spark plug and for cracks in the porcelain, pitted or burned electrodes, excessive carbon buildup, and proper air gap setting. Replace if questionable.

3/4 " (19.05 mm)

3. Remove the blower housing, disconnect the ignition ground lead at the ignition coil (solid state only). Reinstall the blower housing and crank the engine over . If spark occurs, check the ignition switch, saf ety interlock switches, electrical wiring for shorting to ground, or oil shutdown switch.

NOTE: STANDARD POINT IGNITION MAY HA VE T O BE DISCONNECTED A T THE IGNITION SHUTOFF (AT THE SPEED CONTROL).

4. Check the air gap between the flywheel magnets and the laminations of an externally mounted coil or module. It should be .0125 (.317 mm) or use gauge part # 670297.

5. Check the flywheel magnets for the proper strength using this rough test. Hold a screwdriver at the extreme end of the handle with the blade down, mov e the blade to within 3/4 inch (19.05 mm) of the magnets. If the screwdriver blade is attracted to the magnets, the magnetic strength is satisfactory (diag.

16).

6. Examine the stator components (diag. 17). A. Check the ignition cam for roughness. B. Check the movable point arm that rests on the

ignition cam for wear.

MAGNETS

C. Check the spring steel on the point assembly for

evidence of excessive heat.

D . Check contact points for wear. If they are pitted or

burned, this is an indication that the condenser is not functioning properly. If any of the above are faulty, replace accordingly.

E. When replacing the points, also replace the

condenser.

F. After the points are replaced and engine is re-

timed, be sure to clean the points with lint free paper. An engine will not run smoothly if the points are improperly set or coated with even a small quantity of oil, etc.

7. Examine the coil and lamination assembly (either internal or external) for cracks in the insulation or other damage which would cause shorts or leakage of current. Make sure the electrical leads are intact, especially where they enter the coil (diag. 18).

8. Check the operation of the coil using an approved tester. Follow the instructions furnished with the test unit or booklets offered by the Tecumseh Products Co. Engine and Transmission Group Ser vice Division. If the coil or lamination assembly is defective, replace as necessary.

NOTE: IF LAMINATIONS ARE BAD ON AN INTERNAL COIL ASSEMBLY, THE ENTIRE STATOR BODY MUST BE REPLACED SINCE THE LAMINATIONS ARE PERMANENTLY RIVETED TO THE STATOR.

External coils are permanently attached to the lamination and must be serviced as an assembly.

SERVICE

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To remove ignition components from the engine, see Chapter 9 under "Disassembly".

SPARK PLUG SERVICE

Spark plugs should be removed, cleaned, and adjusted periodically.

Check the air gap with a spark plug gap gauge and adjust accordingly. Set the spark plug gap at .030" (.762 mm) (diag. 19).

Replace the plug if the center and ground electrodes are pitted or burned, or if the porcelain is cracked or discolored.

When reinstalling the plug make sure it is clean of all foreign material. NOTE: DO NO T USE A SAND BLASTER T O CLEAN PLUGS, MICR OSCOPIC P AR TICLES LEFT IN THE PLUG CAN

SCORE THE ENGINE CYLINDER DURING OPERATION. USE A SOLVENT AND A WIRE BRUSH T O CLEAN, AND BLOW OUT THOROUGHLY WITH COMPRESSED AIR.

Replace the spark plug with the proper spark plug. Consult the proper parts breakdown for the spark plug to be used in the engine being serviced.

Set the spark plug gap at .030" (.762 mm). Install the spark plug and tighten to 180 inch pounds torque (20.5 Nm). If a torque wrench is not av ailable , screw spark

plug in as far as possible, by hand, and use a spark plug wrench to turn spark plug 1/8 to 1/4 of a turn further if using the old spark plug or 1/2 of a turn further if using a new spark plug.

CONDITIONS CAUSING FREQ UENT SPARK PLUG FOULING

1. Carburetor setting too r ich or air cleaner restricted.

2. Partially closed choke shutter.

3. Poor grade of gasoline.

4. Improper fuel.

5. Restr icted exhaust system.

NORMAL

CARBON DEPOSIT

6. Incorrect spar k plug.

7. Incorrect spar k plug gap.

8. Oil level too high, or breather is restricted.

9. Faulty piston rings.

10. Weak ignition system.

IGNITION TIMING PROCEDURE

In order for an engine to run effectiv ely and efficiently, the spark must ignite the compressed air-fuel mixture when the piston is in a specific position to deliver maximum power. This position is kno wn as Before Top Dead Center (BTDC). If the mixture is ignited too soon, kickback can be e xperienced due to preignition. If the mixture is ignited too late , loss of power can be experienced due to retarded spark.

The Standard P oint System

Internal coils are used on small and medium frame 4 cycle engines. First chec k the specification charts in the back of this manual or the quick reference chart for the correct ignition dimensions , (point gap setting and timing specification) depending on the model of engine.

WORN

OIL DEPOSIT

Begin the procedure by replacing the points if necessary .

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T o do this remo ve the nut that secure the mov able portion of the breaker points. Remove the screw from the stationary portion of the breaker points and the worn breaker point assembly. Install a new breaker point assembly and adjust the point gap. This is done by rotating the crankshaft until the point arm is resting on the high side of the ignition cam. Set the point gap by loosening the screw on the movable point set and insert a feeler gauge per specification. Adjust the point gap so that a light drag is felt on the feeler gauge. Tighten the screw and recheck the gap. Leave the leads unattached for the timing procedure. Use this procedure on all standard point ignition systems when point replacement is necessary (diag. 21).

CRANKSHAFT

ARM

PIVOT

IGNITION

CAM

POINTS

DIAL SCREW

Install a dial indicator (Part # 670241), equipped with the correct tip on the extender leg. Use the small tip for engines with timing dimensions of between top dead center (T.D.C.) and .050" (1.27 mm) before top dead center (B.T .D .C .). Use the large tip f or engines with timing dimensions of between .051" (1.295 mm) B.T.D.C. to .150" (3.81 mm) B.T.D.C. Make sure to secure the extender leg in position to locate the tip directly over the piston head. Loosen the scre w on the side of the adaptor sleeve to allo w the sleev e to be turned into the threads of the spark plug hole, not the entire dial indicator. This will ensure the proper location of the tip. Once the adapter sleeve is secured in the hole, tighten screw on sleeve adaptor to prevent the dial from moving up or do wn, which would give a false reading (diag. 22).

Find T.D.C. with both valves closed by rotating the crankshaft clockwise when looking at the magneto end of the crank, until the needle on the dial stops and reverses direction. Where the needle stops is T.D.C. Loosen the screw on the dial, and rotate the dial so that zero is lined up with the needle at T.D.C. Tighten the screw on the dial to secure it in place (diag. 23).

While watching the needle on the dial indicator, rotate the crankshaft counterclockwise when looking at the magneto end of the crank, .010" (.254 mm) past the B.T.D. C. dimension. Then rotate the crankshaft clockwise to the proper B.T.D.C. dimension, this will take out any slack between the connecting rod and crankshaft assembly.

SLEEVE

DIAL AT

.090"

(2.286 mm)

SLEEVE

SCREW

DIAL AT 0"

DIAL AT

.080"

(2.032 mm)

Example: If the specification of .080" (2.032 mm) is the B.T.D.C. dimension, rotate the crankshaft counterclockwise so that the needle on the dial indicator travels to .090" (2.286 mm) B.T.D.C. (diag. 24), then rotate the crankshaft clockwise so that the needle travels to the specified dimension of .080" (2.032 mm) B.T.D.C. (diag.

25).

Next, if the original breaker points are being used, disconnect the leads from the point terminal. Reinstall the nut & tighten. Connect one lead of a continuity light, or ohmmeter to the point terminal and the other lead to a good ground. Loosen the two bolts holding down the stator and rotate the stator until the continuity light or ohmmeter indicates a break in the circuit. Torque down the stator bolts while maintaining the stator plate position and the timing procedure is completed. Reconnect the leads on the point terminal and tighten the nut making sure that the leads do not touch the flywheel (diag. 26).

(continued on top of next page)

Before putting the dust cover back on the points box,

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clean the points by sliding lint free paper back and forth between the contacts. Manually, open the points when removing the paper to eliminate paper fibers from remaining between the contact points (diag. 27).

Fixed Timed System (External coil)

This system has the contact points and condenser mounted under the flywheel with the laminations and coil mounted outside the flywheel. This system is identified by the square hole in the stator, the round configuration of the coil, and on older coils, the word "Grey Key" is stamped on the coil to identify the proper flywheel key to be used. When ordering an e xternal coil f or replacement from Tecumseh Products, a solid state module will be received as a replacement. The new module will be supplied with the proper flywheel key (diag. 28).

T orque down the stator bolts to secure the stator in place . Next, rotate the crankshaft until the point arm is resting on the high side of the ignition cam. Set the point gap at .020" (.508 mm), by loosening the screw on the mov ab le point, and insert a .020" (.508 mm) feeler gauge between the contact points (diag. 29). Tighten the screw on the movable point and then rechec k the point gap . Be sure to clean contact points with lint free paper (diag. 27).

LINT FREE PAPER

NOTE: The flywheel key used on engines with an e xternal coil and points looks similar to the solid state key , ho wev er, timing will be effected if the wrong key is used.

Reinstall the proper flywheel key, flywheel, washer and torque down the flywheel nut to specification. Reinstall the external coil and set the proper air gap to .0125" (.3175 mm) using air gap gauge, part # 670297 between the magnets and laminations and torque the mounting screws to specification. Remove the air gap gauge and rotate the flywheel to check for any possible striking points. If none are found, the air gap is set correctly and the timing procedure is completed (diag. 30).

Solid State Ignition Timing

Timing is set using a .0125" (.3175 mm) air gap gauge (Part No. 670297). Loosen the two hold-down screws, insert the .0125" (.3175 mm) remove semi-color gauge between the laminations and the magnet on the flywheel. Slide the solid state ignition assembly against the air gap gauge and the flywheel magnet. T orque the tw o hold down screws to the correct specification and remove the air gap gauge. Rotate the flywheel one full revolution to chec k for any possible striking points. If none are found, the air gap is set correctly and the timing procedure is completed (diag. 30).

.0125

(.3175 mm)

Other Solid State Systems

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The following systems are located under the flywheel. All components are encapsulated into one module. No timing is necessary with this type (diag. 31, 32, 33).

Check the system by checking for a spark or use a commercially available test equipment.

SERVICE TIPS

DO NOT :

Interchange flywheels, flywheel keys, spark plugs, condensers, or points. (Some systems do not use standard points and condensers.)

Use flywheels with cooling fins that are broken off. Reglue ceramic magnets back onto the inside of the

flywheel. Re-oil the cam wiper in a magneto system. Use a standard business card as an air gap gauge. File the contact points.

Attempt to reglue the spark plug lead back into a coil or a solid state module.

Store a solid state module within 20 feet (6.1 meters) of an unshielded welder.

PLEASE DO:

Follow directions carefully. Lookup the correct ignition dimensions in the proper

mechanic's manual or quick reference chart, for the engine being repaired.

Clean points with lint free paper after setting gap. Reinstall the point terminal nut and tighten after

removing leads, before timing procedure. Remember to correctly TIME a Tecumseh engine,

even when just changing points on a magneto system.

Remember to use correct air gap gauge. Check for correct flywheel key which effects timing.

CHAPTER 9 INTERNAL ENGINE AND CYLINDER

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GENERAL INFORMATION

This chapter covers the cylinder block, piston and rod assemblies, cylinder head, crankshaft, camshaft, valve train, breather, cylinder cov er, flywheel, counterbalance systems, and lubrication systems. The go vernors and the gov ernor systems are covered in Chapter 4.

All Tecumseh engines covered in this manual are four cycle engines with the valv es in the engine block. The crankshaft position is designated as either horizontal or vertical as the engine rests on its base. The engines identified by decals or model as XL (Extra Life) or XL/C (Extra Life / Commercial ) are made using aluminum alloy diecast around a cast iron cylinder liner. However , not all engines with cast iron cylinder liners are identified as XL or XL/C . Engine blocks of the heavy frame series (HH, VH) are made of cast iron. All other engines use aluminum alloy for the cylinder block along with pistons that are chromium plated.

OPERATION

4-CYCLE ENGINE THEORY

All 4-cycle engines require four piston strokes to complete one power cycle. The flywheel on one end of the crankshaft provides the inertia to keep the engine running smoothly between power strokes.

The camshaft gear is twice as large as the mating gear on the crankshaft so as to allow proper engine valve timing for each cycle. The crankshaft makes two re volutions for every camshaft revolution.

1. INTAKE. The intake valve is open and the exhaust valve is closed. The piston is traveling downward creating a low pressure area, drawing the air-fuel mixture from the carburetor into the cylinder area above the piston (diag. 1).

2. COMPRESSION. As the piston reaches Bottom Dead Center (BDC) the intake valv e closes. The piston then rises, compressing the air-fuel mixture trapped in the combustion chamber (diag. 2).

3. POWER. During this piston stroke both valves remain closed. As the piston reaches the Before Top Dead Center (BTDC) ignition point, the spark plug fires, igniting the air-fuel mixture. In the time it takes to ignite all the available fuel, the piston has moved to Top Dead Center (TDC) ready to take the full combustive force of the fuel for maximum po wer during downward piston travel. The expanding gases force the piston down (diag. 3).

4. EXHAUST. The exhaust valve opens. As the piston starts to the top of the cylinder, the exhaust gases are forced out (diag. 4).

COMPRESSION INTAKE

After the piston reaches Top Dead Center (TDC), the four stroke process will begin again as the piston moves downward and the intake valve opens.

POWER

EXHAUST

LUBRICATION SYSTEMS

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The lubrication system used with all Tecumseh horizontal crankshaft engines covered in this manual utiliz e a splash type system. An oil dipper on the connecting rod splashes oil in the crankcase to lubricate all internal moving parts. Some engines have the dipper as an integral part of the connecting rod assembly, while others have a dipper that is bolted on with one of the rod bolts (diag. 5).

All vertical shaft engines use a positive displacement plunger oil pump or rotary type oil pump. Oil is pumped from the bottom of the crankcase, up through the camshaft and over to the top main bearing. Oil under pressure lubricates the top crankshaft main bearing and camshaft upper bearing (diag. 6).

On all Tecumseh vertical shaft 4-cycle engines, the oil is sprayed out under pressure through a small hole betw een the top camshaft and crankshaft bearing to lubricate the piston, connecting rod, and other internal parts (diag. 7).

The plunger style oil pump is located on an eccentric on the camshaft. As the camshaft rotates, the eccentric moves the barrel back and forth on the plunger forcing oil through the hole in the center of the camshaft. The ball on the end of the plunger is anchored in a recess in the cylinder cover (diag. 8).

CRANKSHAFT

PASSAGE

PLUG

CAMSHAFT

DRILLED

CAMSHAFT

PASSAGE

DIPPER

SPRAY

MIST HOLE

MAIN BEARING OIL

GROOVE

CRANKSHAFT

OIL PASSAGE

CURRENT

(TVM195, 220)

BARREL TYPE

LUBRICATION

PUMP

ASSEMBLE PUMP BARREL

WITH INSIDE CHAMFER

TOWARD CAMSHAFT GEAR

Some Tecumseh engines may be equipped with an UltraBalance® counterbalance system. This system uses a single weighted shaft that is driven off the crankshaft. The shaft's function is to counteract the imbalance caused by the counterweights on the crankshaft and the combustion forces (diag. 9).

SPRAY

MIST HOLE

OIL DRAIN

HOLE

COUNTERBALANCE SYSTEMS

DRIVE GEAR

CAMSHAFT

COUNTERBALANCE

SHAFT

GOVERNOR

FLANGE

COMPONENTS

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The cylinder bloc k houses the piston, valv es and along with the cylinder cov er all the internal components. The bloc k is a one piece diecast aluminum alloy or cast iron cylinder casting (diag. 10).

The piston transmits the force of the burning and expanding gases through the connecting rod to the crankshaft. The piston rings provide the seal between the cylinder wall and the piston. The rings keep the combustion pressures

from entering the crankcase and also wipe the oil off the cylinder wall and return it to the sump. The connecting rod assembly is the link between the piston (piston pin) and the crankshaft. The cylinder head is a one piece aluminum alloy or cast iron casting that is bolted to the top of the cylinder bloc k. The

many fins provide cooling for the engine. The crankshaft converts the up and down piston movement to the rotational force (torque) by an offset crankpin or

rod journal. The camshaft lobes raise and lower the lifters at the proper time to allow air and fuel in and exhaust out of the

cylinder. Teeth on the camshaft gear time the camshaft to the crankshaft. The valves allow air-fuel mixture to enter the cylinder and exhaust gases to exit. The valves provide a positive seal

when closed. The valve springs return the valves to the closed position and must be strong enough to maintain v alve lifter and cam

lobe contact. The valve retainers lock the spring to the valve stem. The valve lifters maintain contact on the camshaft and push the valves open. The crankcase breather is a one way check valve that allows air out and prevents air from coming in. It allows the

engine to develop a partial vacuum in the crankcase during operation. The cylinder cover (or flange on verticals) provides the bearing surface for the power take off (P.T.O.) end of the

crankshaft and camshaft. This bolted on cover is removed to provide access to all internal components. The oil pump (vertical shaft only) consists of a steel plunger and a nylon housing that rides on the camshaft eccentric. The flywheel provides the mass to smooth the effects of one po wer stroke e very other crankshaft revolution. Flywheels

are made of aluminum alloy or cast iron. The flywheel fins act as a fan to cool the engine.

CYLINDER COVER

CYLINDER HEAD

CYLINDER BLOCK

PISTON RINGS

PISTON

VALVES

CONNECTING

ROD

CRANKSHAFT

VALVE LIFTERS

CAMSHAFT

VALVE SPRINGS

CRANKCASE BREATHER

FLYWHEEL

ENGINE OPERA TION PROBLEMS

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ENGINE KNOCKS

Associated equipment loose or

improperly adjusted

Check for excessive carbon in

combustion chamber

Loose flywheel, examine key,

keyway, and proper flywheel nut

torque

Incorrect spark plug or Ignition

timing

Loose or worn connecting rod

Worn cylinder

OVERHEATS

Excessive engine loading

Low oil level or wrong viscosity oil

Cooling air flow, obstructed or

clogged cooling fins

Carburetor improperly adjusted or

improper RPM setting

Incorrect spark plug

or Ignition timing

Carbon in the combustion chamber

SURGES OR RUNS UNEVENLY

Fuel cap vent obstructed

Dirty carburetor or air filter

Carburetor improperly adjusted

Governor sticking, binding or

improper RPM setting

Carburetor linkage, shafts or

shutters sticking or binding

Incorrect spark plug or Intermittent

spark, check ignition

Incorrect or damaged flywheel key

EXCESSIVE OIL CONSUMPTION

Oil level above full

Wrong viscosity oil

Excessive engine speed

Engine cooling fins dirty causing

overheating

Breather damaged, dirty or

improperly installed

Lean carb setting causing

overheating (adjustable carb)

Piston rings worn

Worn or glazed cylinder

Valve guides worn excessively

Damaged gaskets, seals or

"O" rings

ENGINE OPERA TION PROBLEMS

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ENGINE MISFIRES

Wrong or fouled spark plug

Carburetor improperly adjusted

Valves sticking or not seating properly

Incorrect spark plug or

Ignition timing

Excessive carbon build up

Improper Valve Lash or

Weak valve springs

ENGINE VIBRATES EXCESSIVELY

Bent crankshaft

Attached equipment out of balance

Loose mounting bolts

If applicable counter balance not

properly aligned

BREATHER PASSING OIL

Oil level too high

Excessive RPM or improper governor

setting

Damaged gaskets, seals or "O" rings

Breather damaged, dirty or improperly

installed

Piston rings not properly seated or ring

end gaps are aligned

Angle of operation too severe

LACKS POWER

Air intake obstructed

Lack of lubrication or improper

lubrication

Carburetor improperly adjusted

Exhaust Obstructed

Improper valve lash

Loss of compression (worn rings,

blown head gasket)

TESTING

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ENGINE KNOCKS

1. Check the blade hub, blade adapter, or crankshaft coupler for loose fit, loose bolts, or crankshaft key damage. Remove, inspect, replace if necessary. Reinstall and re-torque the bolts to the proper torque.

2. Check the flywheel key and the flywheel and crankshaft keyway for wear or partial shearing. Replace if any damage is evident. Tighten the flywheel nut to the proper torque.

3. Check for the correct ignition module air gap or the correct timing (point ignition). Replace the points and condenser if the points show any wear, oil, or pitting.

4. Remove the cylinder head and check for excessive carbon in the combustion chamber. Also chec k f or the correct head gasket used, and check the spark plug for proper reach and heat range (correct spark plug for the engine).

5. Check for the proper v alve lash using a feeler gauge, and chec k the internal components (piston, cylinder, connecting rod, crankshaft journal) for excessive clearance.

ENGINE OVERHEATS

1. Make sure the engine is not being overloaded. Remove excess load (sharpen blades, limit operation speed, process less material).

2. Check the oil level and viscosity. Add or replace as necessary.

3. Check for clogged cooling fins or obstructions to the air flow. Remove the blower housing, clean and reinstall.

4. Check the carburetor for correct adjustment or remove and clean the carburetor using tag wire and compressed air. See Chapter 3 under "Ser vice."

5. Check the engine R.P.M. setting using a vibratach or other tachometer and compare it to the R.P.M. settings found on microfiche card #30 according to the engine model and specification number. Adjust as necessar y.

6. Make sure the correct spark plug is being used. Check the ignition timing. See Chapter 8 "Ignition - Ser vice." Correct flywheel key or partially sheared key.

7. Remove the cylinder head to check for excessive carbon buildup. Clean as necessar y.

SURGES OR RUNS UNEVENLY

1. Check the fuel cap to make sure it is venting. Loosen the cap and retry engine operation.

2. Replace or clean the air filter.

3. Check the carburetor adjustment or clean the carburetor. See Chapter 3 under "Service."

4. Check the engine R.P.M. setting using a vibratach or other tachometer and compare it to the R.P.M. settings found on microfiche card #30 according to the engine model and specification number. Adjust as necessar y.

5. Visually check all linkages. Check the gover nor shaft, throttle shaft, or pivot points for binding.

6. Check the ignition module operation using a gap type tester inserted in the high tension lead. Chec k for intermittent spark, incorrect spark plug, or a fouled condition.

ENGINE MISFIRES

1. Check the spark plug for the proper application or a fouled condition. Replace if questionable.

2. Reset the carburetor following the adjustment procedure or clean the carburetor. See Chapter 3 under "Service."

3. Check the ignition timing. See Chapter 8 under "Service."

4. Check for carbon buildup in the combustion chamber.

5. Inspect the valves and valve seats for leakage. Check for scor ing or discoloration on the valve stem in the valve guide area. Recut the valves and seats if questionable. See "Valve Service" in this chapter.

(continued on top of next page)

ENGINE VIBRATES EXCESSIVELY

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1. Check the engine crankshaft on the PTO end for bends using a straight edge, square or a dial indicator . Blades or adapters must be removed. Any deflection will cause a vibration problem.

2. Check the engine mounting bolts, make sure they are tight.

3. Remove and check the attached equipment for an out of balance condition.

4. If the engine is equipped with a counterbalance shaft, check the gear timing to determine if the counterbalance is out of time.

BREATHER PASSING OIL

1. Check the oil level, make sure the engine is not overfilled. Also verify that the viscosity rating on the container of the oil being used is to specification.

2. Check the angle of operation. Avoid prolonged use at a severe angle.

3. Check the engine R.P.M. setting f or e xcessive R.P.M. using a vibratach or other tachometer and compare it to the R.P.M. settings found on microfiche card # 30 according to the engine model and specification number . Adjust the high and low R.P.M. as necessary.

4. Check for leaking or damaged gaskets, seals, or "O"-rings. External leaks may not be evident; however, the leak may prevent the engine from achieving a partial crankcase vacuum.

5. Check the breather for damage, dirty condition, or improper installation. The oil return hole(s) must face down.

6. Check the engine compression using a compression tester. If the engine has weak compression, determine the cause of weak compression: worn rings, leaking head gasket, or leaking valves. Follow the compression tester's procedure.

EXCESSIVE OIL CONSUMPTION

1. Check the oil level, oil viscosity on the container of the oil being used, and oil condition. Replace and fill to the proper level.

2. Check the angle of operation. Avoid prolonged use at a severe angle.

3. Check for leaking or damaged gaskets, seals, or "O"-rings. External leaks may not be evident, however, the leak may prevent the engine from achieving a partial crankcase vacuum.

5. Check the breather for damage, dirty condition, or improper installation. The oil return hole(s) must face down.

6. Clean the cooling fins to prevent overheating.

7. Check the carburetor setting causing a lean running condition, overheating the engine.

8. Check the engine compression using a compression tester. If the engine has weak compression, determine the cause of weak compression: worn rings, leaking head gasket, or leaking valves. Follow the compression tester's procedure.

9. Check the valve guide clearance for excessive wear.

LACKS POWER

1. Check the air intake for an obstruction (dirty filter, oil saturated filter, other debris).

2. Check the oil level, oil viscosity on the container of the oil being used and oil condition. Replace and fill to the

3. Readjust the carburetor or remove the carburetor for cleaning. See Chapter 3 under "Ser vice."

4. Check the exhaust for a restriction preventing proper exhaust flow.

proper level.

(continued on top of next page)

5. Check the engine valve lash. Reset the valves at the proper lash.

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6. Check the valves for proper seating and valve guide lash. Recondition the valves and seats. Replace the valves if necessary.

7. Check the ignition timing. Check the flywheel key for partial shearing.

SERVICE DISASSEMBLY PROCEDURE

The following procedures apply to most engine models. Actual procedure may vary.

1. Disconnect the high tension lead from the spark plug. Remove the spark plug.

2. Drain the oil from the crankcase. Drain or shut off the fuel supply.

3. Remove the air cleaner assembly.

4. Remove the fuel tank if it is attached to the engine. Fuel tanks may be held on with bolts, scre ws, or some models require taps upward with a soft face hammer loosening the plastic tank wedged in the blower housing slots.

On some LEV engine models, removal of the bezel cover is necessary to view the engine identification or to provide access to the recoil assembly screws. Push in toward the spark end (as shown), lift up to clean the recoil, then pull the cover away from the spark plug to remove. (diag. 11)

5. Remove the blower housing by first unscrewing the screw holding the dipstick tube to the blo wer housing or unscrewing the dipstick tube and removing the remaining bolts on the blower housing.

6. Unplug the ignition kill wire from the ter minal on top of the ignition module and unbolt the ignition module.

COVER BEZEL

FLYWHEEL

TOOL

MODEL AND

D.O.M. NUMBER

DECAL

LOCATED

UNDER COVER

(IF SO EQUIPPED)

SOCKET WRENCH

FLYWHEEL

7. Remove the flywheel nut, washer, and starter cup. Use a strap wrench (part # 670305) to hold the flywheel from turning (diag. 12). Thread the appropriate flywheel knock-off tool part # 670103, (7/16") or part # 670169 (1/2") on the crankshaft until it bottoms out, then back-off one complete turn. Using a large screwdriver, lift upward under the flywheel and tap sharply and squarely on the knock-off tool to break the flywheel loose. If necessary, rotate the flywheel a half turn and repeat until it loosens (diag.

13). A flywheel puller (part # 670306) may be used on engines with cored holes and also on flywheels with holes drilled and tapped (diag. 14).

NOTE: DO NO T USE A JAW TYPE PULLER.

8. Remove the flywheel key, stator, and baffle plate.

9. Remove the muffler.

10. Remove the intak e pipe and the carburetor. Be careful not to bend or damage the linkage when removing. Mark the hookup points or diagram the linkage arrangement to aid in reassembly.

11. Remove the cylinder head.

12. Remove the crankcase breather.

METAL HAMMER

KNOCK OFF TOOL

SCREWDRIVER TO

RAISE FLYWHEEL

(continued on top of next page)

13. Remove the cylinder cover or mounting flange using a seal protector positioned in the seal to prevent seal

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damage. The crankshaft must be free of rust or scale to slide the cover off the crankshaft. H30-HS50 horizontal crankshaft engines with ball bearings on the crankshaft require the oil seal and the snap ring to be removed prior to the cylinder cover removal. On engines equipped with 8 1/2:1 gear reduction, turn the crankshaft to roll the reduction shaft gear off the crankshaft worm gear when removing the cylinder cover (diag. 15, 16, 17, 18).

1. PTO

Shaft

2. Thin

Washer

3. Gear

4. Tang

Washer

5. Thick

Washer

6. Retainer

OIL SLEEVE TOOL

MOUNTING FLANGE

OIL SEAL

OIL SEAL REMOVED

WORM GEAR

14. Remove the internal components. Align the timing marks on all engines except VM70, 80, 100, HHM80, HM70, 80, 100, TVM170, 195, 220 to relieve valve lifter pressure. On these engines it is necessary to rotate the camshaft clockwise three (3) teeth past the aligned position to allow the compression release mechanism to clear the exhaust valve lifter and to allow the camshaft to be removed (diag. 19 & 20).

15. Remove the lifters, rod cap, and balance shaft or gears if applicable.

16. Before removing the piston, remove any carbon from the top of the cylinder bore to prevent ring breakage. Push the piston out the top of the cylinder bore.

17. Remove the valves by using a valve spring compressor to compress the valve spring and rotate the valve spring retainer to allow the valve stem to pass through. Lift the v alves out of the cylinder b lock. Remove the spring assemblies being careful to note the differences, the original placement of the springs and the presence of seals. Reinstall the spring assemblies on the same valve in the reverse order as they are removed.

SNAP RING

BEVELED TOOTH

CRANKSHAFT

GEAR

CAM GEAR

INTAKE CAM

TIMING MARK

CAMSHAFT GEAR

EXHAUST CAM

ROLL PIN

SPRING

PLUNGER (COMPRESSION RELIEF PIN)

CYLINDERS

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Visually check the cylinder for broken or cracked fins or a scored cylinder bore. Check the main bearings for wear or scoring. If the main bearings are worn or scored they can be replaced on some models. See "Crankshaft Bearing Service" in this chapter.

Use a dial bore gauge or telescoping gauge with a micrometer to accurately measure the cylinder bore. Measure in the piston travel area appro ximately 1/2 to 3/4 of an inch (12.7 to 19.05 mm) from the top and the bottom . Measure at 90 degrees to the piston pin, 45 degrees to the piston pin, and even with the piston pin as the piston would appear when assembled. A rigid hone is recommended to "true" any cylinder irregularities. If the cylinder bore is worn more than .005" (.127 mm) oversize , out of round or scored, it should be replaced or re-siz ed to .010 or .020 ov ersiz e (.254 mm or .508 mm). In some cases engines are b uilt with ov ersize cylinders . If the cylinder is ov ersiz e, the ov ersize v alue will be imprinted in the top of the cylinder (diag. 23).

To re-size a cylinder, use a commercially available hone of the proper size. Chuck the hone in a drill press with a spindle speed of about 600 R.P.M.

Start with coarse stones and center the cylinder under the drill press spindle. Lower the hone so the lower end of the stones contacts the lowest point in the cylinder bore.

Rotate the adjusting nut so that the stones touch the cylinder wall and begin honing at the bottom of the cylinder. A light honing oil should be used to lubricate and cool while honing. Mov e the hone up and down at a r ate of 50 strok es per minute to avoid putting ridges in the cylinder wall. Every fourth or fifth strok e, mo v e the hone f ar enough to e xtend the stones one inch beyond the top and bottom of the cylinder bore.

Check the bore diameter every twenty or thir ty strokes for size and a 35o - 45o crosshatch pattern. If the stones collect metal, clean the stones with a wire brush when the hone is removed. (diag. 21).

Hone with the coarse stones until the cylinder bore is within .002 inch (.051 mm) of the desired finish size. Replace the coarse stones with finishing stones and continue honing the cylinder to the final size. Tecumseh recommends using a 390 grit hone for finishing.

Clean the cylinder and crankcase with soap and water and dry thoroughly.

Replace the piston and the piston rings with the correct oversize parts as indicated in the parts manual.

Trenching has been incorporated in the cylinders of the H50, H60, HHM80, and HM100 series of engines, as well as the TVM125,140, and 220 models. T renching improv es air/fuel flow and results in increased horsepower in these engines. When reinstalling the piston, rings, and rod assembly in these engines, stagger the ring end gaps and place the ring end gaps out of the trenched area. This will prevent the rings from possibly catching the trenched area and breaking during assembly (diag. 22).

TRENCHING

GAPS

STAGGER RING END GAPS AWAY FROM TRENCHING

INDICATES

.010 OVERSIZE

CYLINDER

CYLINDER HEADS

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Check the cylinder head for warpage by placing the head on a precision flat surface. If war ped in excess of .005" (.13 mm) replace the head. Slight warpage can be corrected by placing a sheet of #400 wet /dry sandpaper on a precision flat surface and rubbing the head gasket surface in a circular pattern until the entire gasket surf ace shows evidence of sanding. A small amount of honing oil on the sandpaper will make it easier to slide the head. Always replace the head gask et and torque the head bolts in 50 inch pound increments in the numbered sequence to 200 inch pounds (22.5 Nm) (diag. 24 & 25).

Engine models V50, H50, H60, H70, VH50, VH60, VH70 require a flat and a belleville washer on bolts numbered 1, 3, and 7. Current production HM80 and HM100 use flat washers only on bolts numbered 2 and 3 in conjunction with the gas tank mounting bolts. All other head bolts on HM80 and HM100 use a flat and a belleville washer on each bolt.

Engine models V60, V70, TVM125, 140, 195, 220 require a flat washer and a belleville washer on all head bolts.

PISTONS, RINGS, AND CONNECTING RODS

ALL MODELS EXCEPT HM,VM, TVM170,195,220

TVM170,195,220,VM & HM MODEL ENGINES

BELLEVILLE WASHER

(CROWN TOWARD

BOLT HEAD)

INDICATES .010

OVERSIZE PISTON

FLAT

WASHER

Piston

The piston should be checked for wear by measuring at the bottom of the skirt 90 degrees from the piston pin hole with a micrometer. Check the ring side clearance using a feeler gauge with new ring. Clean all carbon from the piston top and the ring grooves before measuring. Visually inspect the piston skirt area for scoring or scratches from dirt ingestion. If scoring or deep scratches are evident, replace the piston.

If the cylinder bore needs re-sizing, an oversize piston will be necessary. Oversize pistons are identified by the imprinted decimal oversize v alue imprinted on the top of the piston (diag. 26).

Rings

After the cylinder bore diameter has been checked and is acceptable to rebuild, the ring end gap should be checked using ne w rings. Place a new compression ring squarely in the center of the ring travel area. Use the piston upside down to push the ring down (diag. 28) and measure the gap with a feeler gauge. The ring end gap must be within the specification to have adequate oil control (diag. 29). This procedure will assure correct piston ring end gap measurement. Ring side clearance should also be checked with a feeler gauge when using new rings with an old piston (diag. 27).

PISTON MEASUREMENTS ARE TAKEN AT

BOTTOM OF SKIRT 900 FROM WRIST PIN HOLE

1ST COMPRESSION RING

SIDE CLEARANCE

3RD OIL

2ND

COMPRESSION

RING

CYLINDER

CONTROL RING

PISTON

PISTON RING

Replace the rings in sets and install the piston, rings, and rod assembly in the cylinder bore with the ring end gaps staggered. When installing new rings in a used cylinder, the cylinder wall should be de-glazed using a commercially available de-glazing tool or hone.

(continued on top of next page)

Use a ring expander to remove and replace the rings. Do

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not spread the rings too wide or breakage will result. The top compression ring has an inside chamfer, this

chamfer must face UP. If the second compression ring has an inside chamfer, the chamfer must face DOWN in all engines except for HM100 and TVM220 engines where the chamfer faces UP. If there is a notch on the outside diameter, the notch goes DOWN.

The oil control ring can be installed with either side up. The expander (if equipped) end gap and the ring end gap should be staggered (diag. 30).

1ST COMPRESSION RING

2ND COMPRESSION RING

PISTON RING PLACEMENT FOR

HM100, TVM220 ENGINES

EMISSION RINGS

3RD OIL

CONTROL RING

1ST

COMPRESSION

RING

Emission Rings

Used on TVS, LEV, H35, VLV, HM80 and TVXL195 engines that comply with emission standards. These rings have a narrower width and a diff erent profile (barrel faced). The underside of the oil control ring utilizes a coil type expander.

These rings conform better to the cylinder allowing for better oil control by wiping the cylinder wall cleaner. The coiled expander ring helps create a more uniform load on the cylinder wall which gives a more consistent distribution of oil. NOTE: The use of these rings on a standard non-emission piston will cause ring breakage due to its wider ring grooves.

Connecting Rods

Some engine models have offset piston pins (not centered) to centralize the combustion f orce on the piston. Engine models LAV50, HM70, HM80, HHM80, HM100, TVM170,195, 220, have offset pistons. When installing the connecting rod to the piston it is imperative that the rod be installed correctly . The piston used on these models will have either an arrow stamped above the piston pin hole, a number cast on the inside of the piston skirt or an arrow stamped on the top of the piston (diag. 32 &

33). All other engine models use a centered piston pin. If the piston does not have an arrow or number cast inside , the piston can be installed in either direction on the connecting rod. On all engine models, the match marks

on the connecting rod must align and face out when installing the assembly in the engine (diag. 34 & 35).

The arrow on the top of the piston must point toward the valves when installing it in the cylinder (diag. 32). The inside casting number (if present) must face toward the long side of the connecting rod. If there is an arrow on the side of the piston, the arrow must point toward the short side of the connecting rod. (diag. 32).

On horizontal shaft engines, oil dippers are attached to the bottom connecting rod bolt. Some engines have the oil dipper cast in the rod cap. Consult the specification chart for the proper rod bolt torque when installing the cap. The rod bolts should be torqued in 50 inch pound (5.5 Nm) increments until the specified torque is achieved.

2ND

COMPRESSION

RING

LONG SIDE OF ROD

CASTING NUMBER

VM70, VM100, HM70-100, V80, H80, HHM80, AND TVM SERIES

PISTON AND CONNECTING ROD ASSEMBLIES

WRIST PIN

TVM220 PISTON AND ROD

MATCH MARKS

3RD OIL

CONTROL RING

SHORT SIDE OF ROD

ARROW

DIRECTION

ARROW POINTS

TOWARD THE

VALVES

MATCH MARKS

MATCH

MARKS

3534

CRANKSHAFTS AND CAMSHAFTS

Main Menu

Inspect the crankshaft visually and with a micrometer for wear, scr atching, scoring, or out of round condition. Check for bends on the P.T .O . end using a str aight edge, square or a dial indicator.

CAUTION: NEVER TRY TO STRAIGHTEN A BENT CRANKSHAFT.

CAMSHAFT

GEAR TIMING

MARK

BEVEL

CHAMFER TOOTH

CRANKSHAFT GEAR

PUNCH MARK

SMALL

HOBBING HOLE

The timing marks on the camshaft and the crankshaft gears must be aligned for proper v alve timing. (diag. 36 &

37).

Camshafts

Check the camshaft bearing surfaces for wear using a micrometer. Inspect the cam lobes for scoring or excessive wear. If a damaged camshaft is replaced, the mating crankshaft and governor gear should also be replaced. If the crankshaft gear is pressed on it is not serviceable and the crankshaft must also be replaced.

Clean the camshaft with solvent and blow all parts and passages dry with compressed air, making sure that the pins and counterweights are operating freely and smoothly on mechanical compression relief types.

Camshafts used in rotary mower engines utilize a composite gear (glass filled nylon) for the purpose of reducing internal gear noise.

Mechanical Compression Release (MCR) camshafts have a pin located in the camshaft, that e xtends ov er the exhaust cam lobe, to lift the valve and relieve the engine compression for easier cranking. When the engine starts, centrifugal force moves the weight outward and the pin will drop back down. The engine will now run at full compression (diag. 38).

CRANKSHAFT

GEAR

KEYWAY

SMALL HOBBING

HOLE

CAMSHAFT

GEAR

COMPRESSION

RELEASE

MECHANISM

Some engines are equipped with Bump Compression Release (BCR) camshafts that have a small bump g round on the exhaust lobe of the camshaft to relieve compression (diag. 39).

Newer camshafts are designated as Ramp Compression Release (RCR) and utilize a less aggressive ramp than what is used on the BCR camshaft.

EXHAUST

INTAKE

VALVES

Main Menu

The valves should be checked for proper clearance, sealing, and wear. Valve condition is critical for proper engine performance. V alve clear ance should be checke d before removal from the engine block if a valve problem is suspected or when the valves or seats are recut.

V alve clearance (between the v alve stem and valv e lifter) should be set or checked when the engine is cold. The piston should be at T.D.C. on the compression stroke (both valves closed).

Use a valve grinder or "V" bloc k to hold the v alv e square when grinding the valve stem to obtain the proper clearance (diag. 40).

When servicing the valves, all carbon should be remov ed from the valve head and stem. If the valv es are in a usable condition, the valve f ace should be g round using a valve grinder to a 45 degree angle. If after grinding the valve face the margin is less than 1/32 of an inch (.793 mm), the valve should be replaced (diag. 41).

Valves are not identical. Valves marked "EX" or "X" are installed in the exhaust valve location. Valves marked "I" are installed in the intake valv e location. If the valves are unmarked, the nonmagnetic valve (head) is installed in the exhaust valve location.

T o reinstall the v alves, position the valv e caps and springs in the valve compartment. If the spring has dampening coils, the valve spring should be installed with the dampening coils away from the valve cap and retainer (diag. 42).

RIGHT

1/32"

(.793 mm)

MINIMUM

DIMENSION

FACE

WRONG

MARGIN

FACE

STEM

SPRING MUST BE SQUARE

DAMPENING COILS

LOCATED CLOSER

TOGETHER

Install the valves into the guides making sure the correct valve is in the proper port. The valve stem must pass through the upper valve cap and spring. Hook the valve spring retainer on the groove in the valve stem and release the spring tension to lock the cap in place. Early models may hav e a pin through the valve stem. Compress the spring and cap and use a needle nose pliers to insert the pin in the valve stem hole. Release the spring and check that the pin is locked under the cap.

NOTE: If the spring has dampening coils, the y always go toward the stationary surface.

V alve Seats

Main Menu

V alve seats are not replaceab le . If they are burned, pitted, or distorted they can be reground using a grinding stone or a valve seat cutting tool. V alve seats are ground to an angle of 46 deg rees. Check the specifications section for proper width.

The recommended procedure to properly cut a valve seat is to use the Neway Valve Cutting System, which consists of three different cutters. LEV engines have a small combustion chamber and require the use of a special Neway cutter #103 for the 46 and 31 degree combination cutter. The 60 degree cutter is Neway cutter #101. The tapered pilots required are; Neway #100-1/4-1 for the .249 (6.325 mm) exhaust guide, and Neway #100-1/4 for the .250 (6.35 mm) intake guide. Consult the cutter's complete procedure guide for additional information.

NOTE: The v alve seats are cast into the engine bloc k at a slight angle on the LEV engines. When reconditioning valve seats on the LEV engine, the seat cutter will make simultaneous contact with the seat and the aluminum portion of the engine block. There is no detrimental effect to performance or life of the valve seat or block from the procedure.

First, use the 60 degree cutter to clean and narrow the seat from the bottom to the center (diag. 43). Second, use the 31 degree cutter to clean and narrow the seat from the top toward the center (diag. 44). Third or last, use the 46 degree cutter to cut the seat to a width of 3/64" (1.191 mm) (diag. 45).

BOTTOM

NARROWING

CUTTER

BOTTOM

NARROWING

TOP

SEAT

NARROWING

CUTTER

TOP

NARROW

3/64"

(1.191 mm)

SEAT

BOTTOM

NARROW

SEAT CUTTER

31 46

V alve Lifters

The valve lifters on some engines are different lengths. The shor ter lifter is installed in the intake position and the longer lifter is installed in the exhaust position. When removing, mark the lifters to install the lifter in the same position as it was removed from.

Oversize Valve Guides

The valve guides are permanently installed in the cylinder block. If they get worn excessively, they can be reamed oversize to accommodate a 1/32" (.793 mm) oversize valve stem.

The guides should be reamed oversize with a straight shanked hand reamer or low speed drill press. Refer to the "Table of Specifications" (Chapter 10) to determine the correct oversize dimension. Reamers are available through your local Tecumseh parts supplier. Consult the tool section in Chapter 11 for the correct part numbers.

The upper and lower valve spring caps must be redrilled to accommodate the oversize valve stems. After oversizing the valve guides, the valve seats must be recut to align the valve seat to the valve guide.

CRANKCASE BREATHERS

The breather element and case can be cleaned using cleaning solvent. Make sure the small drain hole or holes are clean and installed facing down, so as to allow oil to return back into the crankcase.

Top Mounted Breather

This type of breather is mounted in the top and rear of the cylinder block in vertical shaft engines. The check valve allows positive pressure to be vented through the element and out the tube. Some engines have the breather tube connected to the air cleaner assembly (diag.

46).

ELEMENT

BAFFLE

OIL RETURN

TUBE

CHECK VALVE

PRESSURE OUT

Late production top mounted breathers use the rubber

Main Menu

boot and breather tube as a push in design. Mark or note the location of the breather tube. Use a large flat blade screwdriver to pry the boot up and lift the breather assembly out. Be careful not to drop the breather body out of the rubber boot when removing (diag. 47).

A new breather tube boot is recommended for replacement to assure proper crankcase seal. Apply engine oil to the breather tube boot and push the breather in until the top shoulder of the boot contacts the crankcase.

Side Mounted Breather

This type of breather mounts over the valv e compartment and uses a reed style check valve. Most horizontal shaft engines use this style of breather. The filter element is held in place by a small barb in the cover. To remove the filter, insert a knife blade between the filter element and the barb, and depress the filter element (diag. 48).

Some engine models have two gaskets installed next to the cylinder block. If two gaskets w ere originally installed, replace them using two gaskets (diag. 49).

Integral Breather

Some ECV engines are equipped with breathers that are part of the cylinder block. V enting is accomplished through passages drilled in the block to route the air flow to the outside (diag. 50).

COVER

GASKET

IDENTIFICATION

GASKET

BAFFLE

COVER

PLATE

BODY

REED

DRAIN

HOLE

48 49

RETURN HOLE

ONE WAY

DISC VALVE

ONE WAY

DISC VALVE

WELCH

PLUG

GASKET

FILTER

GASKET

RETURN

HOLE

BODY

GASKET

COVER

COVER PLATE

BAFFLE

TUBE

CYLINDER COVER, OIL SEAL, AND BEARING SERVICE Cylinder Cover

The following procedures, except oil seal replacement, require engine disassembly. See "Disassembly Procedure" in this chapter.

Clean and inspect the cover , look for w ear and scoring of the bearing surfaces. Measure the bearing surface diameters using a micrometer and check the specifications for worn or damaged parts. Replace as necessary.

When reinstalling the cover , apply a drop of Loctite 242 to the cov er screw threads and re-torque to the recommended specification. Always use new oil seals and gaskets after disassembly.

Oil Seal Service

Main Menu

NOTE: BEFORE REMOVING THE OIL SEAL, CHECK TO SEE IF THE SEAL IS RAISED OR RECESSED. WHEN INSTALLING A NEW OIL SEAL, TAP IT INTO POSITION GENTLY UNTIL IT IS SEATED INTO ITS BOSS. SOME SEALS ARE NOT POSITIONED FLUSH TO THE CYLINDER CO VER. ATTEMPTING TO INSTALL THE SEAL T OO FAR IN CAN CAUSE DAMA GE T O THE OIL SEAL AND ENGINE.

OIL SEAL REMOVER

TOOL: POSITIONED FOR

REMOVAL OF OIL SEAL

OIL SEAL

If the crankshaft is removed from the engine , remov e the old oil seals by tapping them out with a screwdriver or punch from the inside. If the crankshaft is in place, remov e the seal by using the proper oil seal puller (diag. 51).

Select the proper seal protector and driver from the tool list in Chapter 11 to install a new oil seal. Place the oil seal over the protector (spring side of seal faces inw ard) and place it over the crankshaft. Drive the seal into position using the universal driver part no. 670272. The seal protector will insure that the seal is driven in to the proper depth (diag. 52).

CRANKSHAFT BEARING SERVICE Ball Bearing Service (H40-HM100 engines)

To remove the ball bearing from the cylinder cover, the bearing locks will have to be rotated out of the way. First loosen the locking nuts with a socket. Turn the retainer bolts counterclockwise to the unlocked position with a needle nose pliers (diag. 53). The flat side of the retainer will face away from the bearing in the unlocked position (diag. 54).

When reinstalling the locks, the flat side must face the bearing while the locking nuts should be torqued to 15-22 inch pounds (1.695 - 2.486 Nm).

To remove a ball bearing from the crankshaft, use a bearing splitter and a puller (diag. 55).

OIL SEAL

LOCKED

INTERIOR OF COVER

OIL SEAL

DRIVER 670272

OIL SEAL DRIVER

PROTECTOR

UNLOCKED

P.T.O. BALL BEARING

When installing the ball bearing to the crankshaft, the bearing must be heated by either using a hot oil bath or heat lamp to expand the bearing. This will allow the bearing to slide on the crankshaft with no interference fit. Be careful to use adequate protection handling the hot ball bearing. The bear ing and the thrust washer must seat tightly against the crankshaft gear.

FLAT

TURN COUNTER-

CLOCKWISE TO UNLOCK

BALL

BEARING

SPLITTER

FLAT

EXTERIOR OF COVER

TURN CLOCKWISE

TO LOCK

PULLER

COUNTERBALANCE SERVICE

Main Menu

To correctly align the Ultra-Balance® system, rotate the piston to top dead center (TDC) and insert the counterbalance shaft into its boss in the cylinder block with the arrow on the gear pointing toward the crankshaft.

Slide the drive gear on the crankshaft, making sure the drive gear is located on the crankshaft key and that the arrow on the drive gear is aligned with the arrow on the gear on the counterbalance shaft (diag. 56 & 57).

FLYWHEEL SERVICE

Some Tecumseh engines have polypropylene fans that are replaceable. A damaged fan can be replaced by tapping on the outside portion of the fan until it separates from the iron portion of the flywheel (diag. 58).

DRIVE GEAR

CAMSHAFT

KEYWAY

DRIVE

GEAR

GOVERNOR

FLANGE

COUNTER

BALANCE

SHAFT

POLYPROPYLENE

PORTION OF

FLYWHEEL

A new fan ma y be installed b y heating the polypropylene fan in a pan of boiling water. Suspend the fan off the bottom of the pan while heating. Using adequate protection, install the hot fan to the flywheel. Make sure the fan locators fit into the hub area of the flywheel.

Flywheel magnets are factory installed and permanently bonded to the flywheel. If the magnets are damaged or lose their magnetic strength, the flywheel must be replaced.

IRON WHEEL

CHAPTER 10

Main Menu

ENGINE SPECIFICATIONS

The engine specifications listed on the following

pages include tolerances that are considered

acceptable to achieve normal engine operation.

Observed values inside the listed tolerance range

are satisfactory and require no adjustments.

FOUR CYCLE TORQUE SPECIFICATIONS

Main Menu

The torque specifications listed in this chart are to be used for replacing components after disassembly, not for

checking an existing engine bolt torque. Checking a torque value on a new or used engine may be lower due to

torque relaxation that occurs on all engines from thermal expansion and contraction. However, sufficient clamping

force exists and a re-torque is not necessary.

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Main Menu

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Main Menu

All models have point setting of .020" (.508 mm), spark plug gap of .030" (.762 mm), valve seat angle of 460.

All dimensions are in inches.

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* Check to detemine bore size

Notes: (A) VM & HM80 - Displacement 19.41 (318 cc) (B) VM & HM80 - Bore 3-1/8"(79.375 mm) (C) VM & HM80 Piston Dia. 3.1195/3.1205

(79.235/79.261 mm) (D) VH50, 60 .0015/.0055 (.038/.140mm) (E) VH70 .0038/.0073 (.097/.185 mm) (F) VH, HH50-70 Models .003/.031

(.762/.787 mm)

ENGINE SPECIFICATIONS STANDARD POINT IGNITION (CONT.)

Main Menu

All models have point setting of .020" (.508 mm), spark plug gap of .030" (.762 mm), valve seat angle of 460.

All dimensions are in inches.

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031.7

551.7

721.

686.

968.12

288.12

263.52

573.52

.S.U

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400.

800.

240.

250.

2343.

2443.

500.

720.

5160.1

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04HH,04H

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201.

302.

760.1

123.1

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347.8

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686.

269.62

579.62

263.52

573.52

.S.U

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0626.2

400.

800.

530.

540.

7082.

7182.

500.

720.

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,501SVT,04VAL

501LXVT,04SH501VCE011VCE

cirteM

576.66

007.66

201.

302.

988.

341.1

031.7

551.7

721.

686.

783.52

004.52

263.52

573.52

.S.U

0526.2

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400.

800.

530.

540.

7082.

7182.

500.

720.

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5899.

0999.

cirteM

576.66

007.66

201.

302.

988.

341.1

031.7

551.7

721.

686.

783.52

004.52

263.52

573.52

.S.U

0057.2

0157.2

400.

800.

530.

540.

7082.

7182.

500.

720.

5999.

0000.1

0999.

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cirteM

58.96

88.96

201.

302.

988.

341.1

031.7

551.7

721.

686.

783.52

004.52

573.52

783.52

.O.T.PtfahsknarC

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gniraeBtfahsmaC

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retemaiDnotsiP

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evoorGgniR

ecnaraelCediS

.pmoCdn2&ts1

evoorGgniR

ecnaraelCediS

liOmottoB

trikSnotsiP

ecnaraelC

paGdnEgniR

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5378.

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5268.

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200.

500.

100.

400.

0400.

8500.

700.

710.

5000.1

0100.1

5578.

0678.

781.22

002.22

736.21

946.21

598.12

809.12

355.66

375.66

150.

721.

520.

201.

741.

871.

234.

314.52

524.52

832.22

052.22

5899.

0999.

0326.

5326.

0360.1

5360.1

5494.2

0594.2

200.

500.

100.

400.

5500.

0700.

700.

710.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

428.51

738.51

000.72

310.72

063.36

373.36

150.

721.

520.

201.

041.

871.

234.

314.52

524.52

314.52

524.52

5899.

0999.

5794.

0894.

5000.1

0100.1

2026.2

0126.2

200.

500.

100.

400.

0400.

8500.

700.

710.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

736.21

946.21

314.52

524.52

355.66

375.66

150.

721.

520.

201.

741.

871.

234.

314.52

524.52

314.52

524.52

5899.

0999.

5794.

0894.

5000.1

0100.1

2026.2

0126.2

200.

500.

100.

400.

0400.

8500.

700.

710.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

314.52

524.52

736.21

946.21

355.66

375.66

150.

721.

520.

201.

741.

871.

234.

314.52

524.52

314.52

524.52

5899.

0999.

5794.

0894.

5000.1

0100.1

0547.2

5547.2

200.

500.

100.

400.

5400.

0600.

700.

710.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

314.52

524.52

736.21

946.21

327.96

637.96

150.

721.

520.

201.

411.

251.

871.

234.

314.52

524.52

314.52

524.52

* Check to detemine bore size

Notes: (A) VM & HM80 - Displacement 19.41 (318 cc) (B) VM & HM80 - Bore 3-1/8"(79.375 mm) (C) VM & HM80 Piston Dia. 3.1195/3.1205

(79.235/79.261 mm) (D) VH50, 60 .0015/.0055 (.038/.140mm) (E) VH70 .0038/.0073 (.097/.185 mm) (F) VH, HH50-70 Models .003/.031

(.762/.787 mm)

ENGINE SPECIFICATIONS STANDARD POINT IGNITION

Main Menu

All models have point setting of .020" (.508 mm), spark plug gap of .030" (.762 mm), valve seat angle of 460.

All dimensions are in inches.

SNOITACIFICEPS

.S.U

)cc()³ni(tnemecalpsiD

ekortS

eroB

.miDgnimiT

.C.D.T.B

ecnaraelCevlaV

htdiWtaeSevlaV

ediuGevlaV

.miDezisrevO

dnEtfahsknarC

yalP

lanruoJnipknarC

.aiD

40.2143.79140.2143.79181.2136.99135.3167.12240.5115.642

839.132.94839.132.9452.251.755.25.36235.213.46

0218.2

0318.2

530.0988.530.0988.080.0230.2080.0230.2080.0230.2

400.

010.

530.

540.

7082.

7182.

500.

720.

5999.

0000.1

,021SVT,05VAL

05SH

cirteM

524.17

054.17

201.

452.

988.

341.1

031.7

551.7

721.

686.

783.52

004.52

021TNT 021VCE

.S.U

0218.2

0318.2

400.

010.

530.

540.

7082.

7182.

500.

720.

5999.

0000.1

cirteM

524.17

054.17

201.

452.

988.

341.1

031.7

551.7

721.

720.

783.52

004.52

.S.U

800.

210.

240.

250.

500.

720.

,05HV,05V

05HH,05H,521MVT

cirteM

0526.2

0626.2

2343.

2443.

Feton

5160.1

0260.1

576.66

007.66

302.

503.

760.1

123.1

717.8

347.8

721.

720.

269.62

579.62

800.

210.

240.

250.

500.

720.

,06HV,06V

06HH,06H,041MVT

.S.U

0526.2

0626.2

2343.

2443.

Feton

5160.1

0260.1

cirteM

576.66

007.66

302.

503.

760.1

123.1

717.8

347.8

721.

720.

269.62

579.62

.S.U

800.

210.

240.

250.

2343.

2443.

500.

720.

,07HV,07V

,07MV

07HH,07H

cirteM

0057.2

0157.2

Feton

0681.1

5681.1

58.96

88.96

302.

503.

760.1

123.1

717.8

347.8

721.

720.

421.03

731.03

.gaMtfahsknarC

.aiD.grBniaM

.O.T.PtfahsknarC

.aiD.grBniaM

gniraeBtfahsmaC

.aiDdoR.nnoC

.grBknarC

retemaiDnotsiP

trikSfOmottoB

evoorGgniR

ecnaraelCediS

.pmoCdn2&ts1

evoorGgniR

ecnaraelCediS

liOmottoB

trikSnotsiP

ecnaraelC

paGdnEgniR

niaMrednilyC

.grB

rednilyC

egnalF/revoC

gniraeBniaM

retemaiD

5899.

0999.

5899.

0999.

5794.

0894.

5000.1

0100.1

2708.2

0808.2

200.

500.

100.

400.

0400.

8500.

700.

710.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

263.52

573.52

736.21

946.21

314.52

524.52

303.17

323.17

150.

721.

520.

201.

741.

871.

234.

314.52

524.52

314.52

524.52

5899.

0999.

5899.

0999.

5794.

0894.

5000.1

0100.1

2708.2

0808.2

200.

500.

100.

400.

0400.

8500.

700.

710.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

263.52

573.52

736.21

946.21

314.52

524.52

303.17

323.17

150.

721.

520.

201.

741.

871.

234.

314.52

524.52

314.52

524.52

5899.

0999.

5899.

0999.

0326.

5326.

0360.1

5360.1

0126.2

5126.2

200.

400.

200.

400.

5300.

0500. Deton

010.

020.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

263.52

573.52

428.51

738.51

000.72

310.72

375.66

685.66

150.

201.

150.

201.

980.

721.

452.

805.

314.52

524.52

314.52

524.52

5899.

0999.

5899.

0999.

0326.

5326.

0360.1

5360.1

0126.2

5126.2

200.

400.

200.

400.

5300.

0500. Deton

010.

020.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

263.52

573.52

428.51

738.51

000.72

310.72

375.66

5126.2

150.

201.

150.

201.

980.

721.

452.

805.

314.52

524.52

314.52

524.52

5899.

0999.

5899.

0999.

0326.

5326.

0881.1

5881.1

0547.2

5547.2

200.

300.

100.

300.

5400.

0600. Eeton

010.

020.

5000.1

0100.1

5000.1

0100.1

263.52

573.52

263.52

573.52

428.51

738.51

571.03

881.03

327.96

637.96

150.

670.

520.

670.

411.

251.

452.

805.

314.52

524.52

314.52

524.52

* Check to detemine bore size

Notes: (A) VM & HM80 - Displacement 19.41 (318 cc) (B) VM & HM80 - Bore 3-1/8"(79.375 mm) (C) VM & HM80 Piston Dia. 3.1195/3.1205

(79.235/79.261 mm) (D) VH50, 60 .0015/.0055 (.038/.140mm) (E) VH70 .0038/.0073 (.097/.185 mm) (F) VH, HH50-70 Models .003/.031

(.762/.787 mm)

ENGINE SPECIFICATIONS STANDARD POINT IGNITION (Cont.)

Main Menu

All models have point setting of .020" (.508 mm), spark plug gap of .030" (.762 mm), valve seat angle of 460.

All dimensions are in inches.

SNOITACIFICEPS07MH,071MVT

.S.U

)cc()³ni(tnemecalpsiD

ekortS

eroB

.miDgnimiT

.C.D.T.B

ecnaraelCevlaV

htdiWtaeSevlaV

ediuGevlaV

.miDezisrevO

dnEtfahsknarC

yalP

lanruoJnipknarC

.aiD

71.7124.18256.8176.50334.91

235.213.46235.213.46235.2

5739.2

5839.2

090.0682.2090.0682.2090.0682.2090.0682.2090.0682.2

800.

210.

240.

250.

2343.

2443.

500.

720.

0681.1

5681.1

cirteM

316.47

836.47

302.

503.

760.1

123.1

717.8

347.8

721.

686.

421.03

731.03

800.

210.

240.

250.

500.

720.

,*08MV,08V

*08MH,07H

.S.U

0260.3

0360.3

2343.

2443.

0681.1

5681.1

cirteM

577.77

008.77

302.

503.

760.1

123.1

717.8

347.8

721.

686.

421.03

731.03

.S.U

Aeton

Beton

0521.3

0621.3

800.

210.

240.

250.

2343.

2443.

500.

720.

0681.1

5681.1

,591MVT,*08MV

08MHH,*08MH*001MH,001MV*001MH,022MVT

cirteM

64.8132.0280.33328.1236.753

13.46235.213.46235.213.46

573.97

004.97

302.

503.

760.1

123.1

717.8

347.8

721.

686.

421.03

731.03

.S.U

0781.3

0881.3

800.

210.

240.

250.

2343.

2443.

500.

720.

0681.1

5681.1

cirteM

059.08

579.08

302.

503.

760.1

123.1

717.8

347.8

721.

686.

421.03

731.03

.S.U

0213.3

0313.3

800.

210.

240.

250.

2343.

2443.

500.

720.

0681.1

5681.1

cirteM

521.48

051.48

302.

503.

760.1

123.1

717.8

347.8

721.

686.

421.03

731.03

.gaMtfahsknarC

.aiD.grBniaM

.O.T.PtfahsknarC

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gniraeBtfahsmaC

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retemaiDnotsiP

trikSfOmottoB

evoorGgniR

ecnaraelCediS

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evoorGgniR

ecnaraelCediS

liOmottoB

trikSnotsiP

ecnaraelC

paGdnEgniR

niaMrednilyC

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rednilyC

egnalF/revoC

gniraeBniaM

retemaiD

5899.

0999.

0781.1

5781.1

0326.

5326.

0881.1

5881.1

5239.2

5339.2

200.

500.

100.

400.

600.

010.

020.

5000.1

0100.1

0981.1

5981.1

263.52

573.52

051.03

361.03

428.51

738.51

571.03

881.03

684.47

115.47

150.

721.

520.

201.

251.

452.

805.

314.52

524.52

102.03

312.03

5899.

0999.

0781.1

5781.1

0326.

5326.

0881.1

5881.1

5750.3

5850.3 Ceton

200.

500.

100.

400.

5300.

5500.

010.

020.

5000.1

0100.1

0981.1

5981.1

263.52

573.52

051.03

361.03

428.51

738.51

571.03

881.03

166.77

686.77

150.

721.

520.

201.

980.

041.

452.

805.

314.52

524.52

102.03

312.03

5899.

0999.

0781.1

5781.1

0326.

5326.

0881.1

5881.1

5911.3

5021.3

200.

500.

100.

400.

5400.

5600.

010.

020.

5000.1

0100.1

0981.1

5981.1

263.52

573.52

051.03

361.03

428.51

738.51

571.03

881.03

532.97

162.97

150.

721.

520.

201.

411.

571.

452.

805.

314.52

524.52

102.03

312.03

5899.

0999.

0781.1

5781.1

0326.

5326.

0881.1

5881.1

5181.3

5281.3

200.

500.

100.

400.

5400.

5600.

010.

020.

5000.1

0100.1

0981.1

5981.1

263.52

573.52

051.03

361.03

428.51

738.51

571.03

881.03

018.08

638.08

150.

721.

520.

201.

411.

571.

452.

805.

314.52

524.52

102.03

312.03

5899.

0999.

0781.1

5781.1

0326.

5326.

0881.1

5881.1

0903.3

5013.3

200.

500.

100.

400.

5100.

0400.

010.

020.

5000.1

0100.1

0981.1

5981.1

263.52

573.52

051.03

361.03

428.51

738.51

571.03

881.03

940.48

780.48

150.

721.

520.

201.

830.

201.

452.

805.

314.52

524.52

102.03

312.03

* Check to detemine bore size

Notes: (A) VM & HM80 - Displacement 19.41 (318 cc) (B) VM & HM80 - Bore 3-1/8"(79.375 mm) (C) VM & HM80 Piston Dia. 3.1195/3.1205

(79.235/79.261 mm) (D) VH50, 60 .0015/.0055 (.038/.140mm) (E) VH70 .0038/.0073 (.097/.185 mm) (F) VH, HH50-70 Models .003/.031

(.762/.787 mm)

Tecumseh LAV30-50, V40-80, TVM125-220, HSK30-70, HH40-70 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual