TECUMSEH OHH50 - 65, OHHSK50 - 130, OHV11, OVM120, OVRM40-675 User Manual

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TECUMSEH

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

This manual covers engine models:

OHH50 - 65, OHHSK50 - 130, OHV11 - OHV17, OVM120,

OVRM40-675, OVRM120, OVXL/C120, OVXL120, OVXL125.

Other illustrated Tecumseh 2-Cycle Engine, 4-Cycle Engine and

Transmission manuals; booklets; and wall charts are available

through Tecumseh.

For complete listing write or call

CONTAINS SEARS CRAFTSMAN CROSS REFERENCE

4-CYCLE OVERHEAD

VALVE ENGINES

Small Engine Parts

CONTENTS

Page

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

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

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

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

FUELS ............................................................................. 2

ENGINE OIL .................................................................... 2

CAPACITIES.................................................................... 2

OIL CHANGE INTERVALS .............................................. 3

OIL CHECK...................................................................... 3

OIL CHANGE PROCEDURE .......................................... 3

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

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

DRAINING THE FUEL SYSTEM ..................................... 4

OIL CYLINDER BORE .................................................... 4

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

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

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

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

TROUBLESHOOTING OR TESTING ............................. 6

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

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

POLYURETHANE-TYPE FILTER ELEMENT

OR PRE-CLEANER..................................................... 7

PAPER -TYPE FILTER ELEMENT ................................. 7

FLOCKED SCREEN........................................................ 7

CHAPTER 3 CARBURETORS AND FUEL SYSTEMS . 8

GENERAL INFORMATION ............................................. 8

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

FUEL PRIMERS .............................................................. 9

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

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

CARBURETOR VISUAL IDENTIFICATION .................... 10

SERIES I CARBURETORS............................................. 10

SERIES III & SERIES IV CARBURETORS .................... 10

SERIES VI CARBURETORS .......................................... 10

SERIES VII ...................................................................... 10

SERIES VIII ..................................................................... 11

SERIES IX ....................................................................... 11

WALBRO MODEL LMK ................................................... 11

TESTING ......................................................................... 12

SERVICE ......................................................................... 12

CARBURETOR PRE-SETS AND ADJUSTMENTS........ 12

PRE-SETS AND ADJUSTMENTS

(TECUMSEH AND WALBRO CARBURETORS)......... 13

FINAL ADJUSTMENTS ................................................... 13

TECUMSEH CARBURETORS ........................................ 13

WALBRO CARBURETOR ............................................... 13

CARBURETOR DISASSEMBLY PROCEDURE ............. 14

IMPULSE FUEL PUMP ................................................... 15

FLOAT ADJUSTING PROCEDURE................................ 16

INSPECTION ................................................................... 16

THROTTLE AND CHOKE ............................................... 16

IDLE AND HIGH SPEED MIXTURE ADJUSTING

SCREW ........................................................................ 16

FUEL BOWL RETAINING NUT ....................................... 16

FUEL BOWL, FLOAT, NEEDLE AND SEAT ................... 17

ASSEMBLY PROCEDURE ............................................. 18

WELCH PLUGS............................................................... 18

THROTTLE SHAFT AND PLATE .................................... 18

CHOKE SHAFT AND PLATE .......................................... 19

FUEL INLET FITTING ..................................................... 19

HIGH AND LOW SPEED ADJUSTING SCREW,

MAIN NOZZLE ............................................................. 19

Page

INLET NEEDLE AND SEAT ............................................ 20

FLOAT INSTALLATION ................................................... 20

FUEL BOWL AND BOWL NUT ....................................... 21

IMPULSE FUEL PUMP ................................................... 21

PRIMER BULB ................................................................ 21

FINAL CHECKS............................................................... 21

CHAPTER 4 GOVERNORS AND LINKAGE ................. 22

GENERAL INFORMATION ............................................. 22

OPERATION .................................................................... 22

TROUBLESHOOTING .................................................... 22

ENGINE OVERSPEEDING ............................................. 22

ENGINE SURGING ......................................................... 22

SERVICE ......................................................................... 23

GOVERNOR ADJUSTMENT .......................................... 23

GOVERNOR GEAR AND SHAFT SERVICE .................. 23

GOVERNOR GEAR OR SHAFT REPLACEMENT,

UPSET STYLE GOVERNOR SHAFT .......................... 23

GOVERNOR SHAFT REPLACEMENT, RETAINING

RING STYLE ................................................................ 24

SPEED CONTROLS AND LINKAGE .............................. 25

CONVERSION TO REMOTE CONTROL ....................... 27

OVM, OVXL, OHV VERTICAL SPEED CONTROL ........ 28

OHV 11-17 HORIZONTAL SPEED CONTROL............... 28

CHAPTER 5 RECOIL STARTERS ................................. 29

GENERAL INFORMATION ............................................. 29

OPERATION .................................................................... 29

COMPONENTS ............................................................... 29

SERVICE ......................................................................... 29

ROPE SERVICE .............................................................. 29

ROPE RETAINER REPLACEMENT ............................... 30

STYLIZED REWIND STARTER (OHH, OVRM, OHM, OHSK, OVM, OVXL, OHV 11-13), AND STAMPED

STEEL STARTER ......................................................... 30

DISASSEMBLY PROCEDURE ....................................... 30

ASSEMBLY PROCEDURE ............................................. 31

STYLIZED REWIND STARTER WITH PLASTIC

RETAINER.................................................................... 31

DISASSEMBLY PROCEDURE ....................................... 31

ASSEMBLY...................................................................... 32

KEEPER SPRING STYLE STARTERS .......................... 32

DISASSEMBLY PROCEDURE ....................................... 32

ASSEMBLY PROCEDURE ............................................. 33

STYLIZED STARTER (OHV 13.5 -17) ............................ 34

ASSEMBLY...................................................................... 34

CHAPTER 6 ELECTRICAL SYSTEMS .......................... 35

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

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

STARTING CIRCUIT AND ELECTRIC STARTERS ....... 35

CHARGING CIRCUIT ...................................................... 35

CONVERTING ALTERNATING CURRENT TO

DIRECT CURRENT ...................................................... 36

HALF WAVE RECTIFIER SINGLE DIODE..................... 36

FULL WAVE RECTIFIER BRIDGE RECTIFIER ............. 36

COMPONENTS ............................................................... 36

BATTERY......................................................................... 36

WIRING............................................................................ 36

ELECTRICAL TERMS ..................................................... 37

BASIC CHECKS .............................................................. 37

TROUBLESHOOTING ELECTRICAL STARTER

CIRCUIT FLOW CHART .............................................. 38

TROUBLESHOOTING ELECTRICAL CHARGING

CIRCUIT FLOW CHART .............................................. 39

C Tecumseh Products Company

1998

Page

TESTING PROCEDURE ................................................. 40

STARTING CIRCUIT ....................................................... 40

CHARGING CIRCUIT ...................................................... 40

350 MILLIAMP CHARGING SYSTEM ............................ 40

18 WATT A.C. LIGHTING ALTERNATOR....................... 41

35 WATT A.C. .................................................................. 41

2.5 AMP D.C., 35 WATT LIGHTING ............................... 41

3 AMP DC ALTERNATOR SYSTEM - DIODE IN

HARNESS SLEEVE ..................................................... 42

5 AMP D.C. ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER BLOWER

HOUSING ..................................................................... 43

3 AMP D.C. 5 AMP A.C. ALTERNATOR ......................... 43

MODELS OVM/OVXL/OHV12.5 ..................................... 44

MODELS OHV 13.5 - 17 (3/5 AMP SPLIT)..................... 44

MODELS OVM/OVXL/OHV12.5

(RED BETWEEN ENGINE AND DIODE) .................... 44

MODELS OHV 13.5 - 17

(RED BETWEEN ENGINE AND DIODE) .................... 45

7 AMP D.C. ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER ENGINE

HOUSING ..................................................................... 45

10 AMP A.C. ALTERNATOR ........................................... 46

16 AMP ALTERNATOR SYSTEM WITH EXTERNAL

REGULATOR................................................................ 46

VOLTAGE REGULATORS .............................................. 46

FUEL SHUT-DOWN SOLENOIDS .................................. 46

LOW OIL SHUTDOWN SWITCHES ............................... 47

LOW OIL PRESSURE SENSOR .................................... 47

LOW OIL SENSOR.......................................................... 47

ELECTRIC STARTER SERVICE .................................... 48

12 VOLT OR 120 VOLT ELECTRIC STARTERS ........... 48

INSPECTION AND REPAIR............................................ 49

BRUSH CARD REPLACEMENT..................................... 49

CHAPTER 7 FLYWHEEL BRAKE SYSTEMS ............... 50

GENERAL INFORMATION ............................................. 50

OPERATION .................................................................... 50

COMPONENTS ............................................................... 51

SERVICE ......................................................................... 51

BRAKE BRACKET ASSEMBLY ...................................... 52

IGNITION GROUNDOUT TERMINAL............................. 52

STARTER INTERLOCK SWITCH ................................... 52

CONTROL CABLE .......................................................... 52

BRAKE BRACKET REPLACEMENT .............................. 52

CHAPTER 8 IGNITION ................................................... 53

GENERAL INFORMATION ............................................. 53

OPERATION .................................................................... 53

SOLID STATE IGNITION SYSTEM (CDI) ....................... 53

COMPONENTS ............................................................... 53

TESTING PROCEDURE ................................................. 54

FOUR CYCLE IGNITION TROUBLESHOOTING........... 55

SERVICE ......................................................................... 56

SPARK PLUG SERVICE ................................................. 56

CONDITIONS CAUSING FREQUENT SPARK

PLUG FOULING ........................................................... 56

IGNITION TIMING CHECK ............................................. 57

SERVICE TIPS ................................................................ 57

Page

CHAPTER 9 INTERNAL ENGINE AND CYLINDER ..... 58

GENERAL INFORMATION ............................................. 58

OPERATION .................................................................... 58

4-CYCLE ENGINE THEORY .......................................... 58

LUBRICATION SYSTEMS .............................................. 59

COUNTERBALANCE SYSTEMS ................................... 59

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

ENGINE OPERATION PROBLEMS ............................... 61

ENGINE OPERATION PROBLEMS ............................... 62

TESTING ......................................................................... 63

ENGINE KNOCKS ........................................................... 63

ENGINE OVERHEATS.................................................... 63

SURGES OR RUNS UNEVENLY ................................... 63

ENGINE MISFIRES ......................................................... 63

ENGINE VIBRATES EXCESSIVELY .............................. 64

BREATHER PASSING OIL ............................................. 64

EXCESSIVE OIL CONSUMPTION ................................. 64

LACKS POWER .............................................................. 65

SERVICE ......................................................................... 65

DISASSEMBLY PROCEDURE ....................................... 65

CYLINDERS .................................................................... 68

CYLINDER HEAD AND VALVE TRAIN SERVICE ......... 69

VALVES, SPRINGS, AND PUSH RODS ........................ 69

PISTONS, RINGS, AND CONNECTING RODS............. 70

PISTON ........................................................................... 70

PISTON RINGS ............................................................... 70

PISTON RING ORIENTATION ....................................... 70

CONNECTING RODS ..................................................... 71

CRANKSHAFTS AND CAMSHAFTS .............................. 71

CAMSHAFTS................................................................... 71

VALVE SEATS ................................................................. 72

VALVE LIFTERS.............................................................. 73

VALVE GUIDES ............................................................... 73

VALVE GUIDE REMOVAL (OVM, OHM, OHSK110

& 120, OVXL ONLY) .................................................... 73

VALVE GUIDE INSTALLATION (OVM, OHM,

OHSK110 & 120, OVXL ONLY) ................................... 73

CRANKCASE BREATHERS ........................................... 74

TOP MOUNTED BREATHER ......................................... 74

SIDE MOUNTED BREATHER ........................................ 74

CYLINDER COVER, OIL SEAL, AND BEARING

SERVICE ...................................................................... 75

CYLINDER COVER ........................................................ 75

OIL SEAL SERVICE........................................................ 75

CRANKSHAFT BEARING SERVICE .............................. 75

BALL BEARING SERVICE.............................................. 75

SERVICE BUSHING ....................................................... 76

BUSHING SIZE CHART.................................................. 76

ENGINE ASSEMBLY ...................................................... 76

CHAPTER 10 .................................................................. 83

ENGINE SPECIFICATIONS AND SEARS

CRAFTSMAN CROSS-REFERENCE ......................... 83

OVERHEAD VALVE SEARS CRAFTSMAN

CROSS REFERENCE ................................................. 83

ENGINE SPECIFICATIONS............................................ 85

OVERHEAD VALVE TORQUE SPECIFICATIONS ........ 86

OVERHEAD VALVE TORQUE SPECIFICATIONS ........ 87

CHAPTER 11 EDUCATIONAL MATERIALS

AND TOOLS ............................................................... 88

All rights reserved. No part of this book may be reproduced or transmitted, in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without permission in writing from Tecumseh Products Company Training Department Manager.

CHAPTER 1 GENERAL INFORMATION

ENGINE IDENTIFICATION

Tecumseh engine model, specification, and serial numbers or date of manufacture (D.O.M.) are stamped into the blower housing, or located on a decal on the engine in locations as illustrated (diag. 1 & 2). The engine identification decal also provides the applicable warranty code and oil recommendations (diag. 2).

Interpretation of Model Number

The letter designations in a model number indicate the basic type of engine.

OHH - Overhead Valve Horizontal OHM - Overhead Valve Horizontal

MediumFrame OHSK - Overhead Valve Horizontal Snow King OVM - Overhead Valve Vertical Medium Frame OVRM - Overhead Valve Vertical Rotary Mower OVXL - Overhead Valve Vertical Medium Frame

Extra Life OHV - Overhead Valve Vertical

ENGINE MODEL

NUMBER

The number designations following the letters indicate the basic engine model.

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 of the engine.

Using model OHV16-204207A, serial 5215C as an example, interpretation is as follows:

OHV16-204207A is the model and specification number.

OHV Overhead Valve Vertical 16 Indicates the basic engine model. 204207A is the specification number used for

properly identifying the parts of the engine.

5215C is the serial number or D.O.M. (Date of

Manufacture)

5 is the last digit in the year of

manufacture (1995).

215 indicates the calendar day of that year

(215th day or August 3, 1995).

C represents the line and shift on which

the engine was built at the factory.

THIS ENGINE MEETS 1995-1998

CALIF. EMISSION REGULATIONS FOR

ULGE ENGINES AS APPLICABLE

FUEL: REGULAR UNLEADED OIL : USE SAE 30

OHV 125 203000A (D) RTP358UIG2RA 358cc 3057D

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.

NOTE: To maintain best possible emission performance, use only Genuine Tecumseh Parts.

SHORT BLOCKS

SBV OR SBH IDENTIFICATION NUMBER

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. 3).

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

SHORT BLOCK IDENTIFICATION TAG

SBV- 564A SER 5107

SERIAL NUMBER

FUELS

Tecumseh Products Company strongly recommends the use of fresh, clean, unleaded regular gasoline in all Tecumseh Engines. Unleaded gasoline burns cleaner, extends engine life, and promotes good starting by reducing the build up of combustion chamber deposits. Unleaded regular, unleaded premium or reformulated gasoline containing no more than 10% Ethanol, or 15% MTBE, or 15% ETBE may also be used.

Leaded fuel is generally not available in the United States and should not be used if any of the above options are available.

Never use gasoline, fuel conditioners, additives or stabilizers containing methanol, white gas, or fuel blends which exceed the limits specified above for Ethanol, MTBE, or ETBE because engine/fuel system damage could result.

Regardless of which of the approved fuels are used, fuel quality is critical to engine performance. Fuel should not be stored in an engine or container more than 30 days prior to use. This time may be extended with the use of a fuel stabilizer like TECUMSEH'S, part number 730245.

See "STORAGE" instructions in the Technician's Manual, Operators Manual, or Bulletin 111.

ENGINE OIL

TECUMSEH FOUR CYCLE ENGINES REQUIRE THE USE OF A CLEAN, HIGH QUALITY DETERGENT OIL. Be sure original container is marked: A.P.I. service "SF" thru "SJ" or "CD".

TECUMSEH RECOMMENDS USING ONE OF THE FOLLOWING FOUR CYCLE OILS THAT ARE SPECIALLY FORMULATED TO TECUMSEH SPECIFICATIONS.

DO NOT USE SAE10W40 OIL. FOR SUMMER (Above 320 F) (0oC) USE SAE30 OIL. PART #730225

Use SAE30 oil in high temperature, high load applications. Using multigrade oil may increase oil consumption. FOR WINTER (Below 320F) (0oC) USE SAE5W30 OIL. PART #730226 (SAE 10W is an acceptable substitute.) (BELOW 00F (-18oC) ONLY): SAE 0W30 is an acceptable substitute.

NOTE: For severe, prolonged winter operation of HH120 model, SAE10W oil is recommended.

Capacities

Engine Model Oz. ml.

OHH,OHSK 50-70 21 630 OVRM 40 - 6.75 21 630 OVRM105 & 120 21 630 OHSK80 - 100 26 720 OHM, OHSK 110* - 130 32 960 OVM 120, OVXL 120, 125 32 960 OHV 11 - 13 without oil filter 32 960 OHV 11 - 13 with filter 39 1170 OHV 13.5 - 17 without oil filter 55 1650 OHV 13.5 -17 2 1/4" filter (part # 36563) 62 1860 OHV 13.5 -17 2 5/8" filter (part # 36262) 64 1920

* NOTE: Model OHSK110 with a spec. of 221000 and up, have a capacity of 26 oz. (720 ml.)

Oil Change Intervals: Change the oil after the first two (2) hours of operation and every 25 hours thereafter

(OHH & OHSK50-130, OHV13.5-17 every 50 hours), or more often if operated under dusty or dirty conditions. If the engine is run less than 25 hours per year, change the oil at least once per year.

NOTE: The oil filter (if equipped) requires changing every 100 hours or more often if operated under dusty or dirty conditions.

Oil Check: Check the oil each time the equipment is used or every five (5) hours of operation. 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. On some rotary mower applications, where 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. Contact your local governing authorities to find a waste oil disposal site.

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

TUNE-UP PROCEDURE:

NOTE: Today's 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 poor engine performance. 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. See Chapter 2 under "Service".

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, head, cylinder cooling fins, carburetor, governor levers and linkage.

4. Make sure the fuel tank, fuel filter and fuel line are clean. Replace any worn or damaged governor springs or linkage. Make the proper governor adjustments and carburetor presets where required.

5. When replacing the spark plug, consult the proper parts breakdown for the spark plug to be used in the engine being serviced. Set the proper spark plug gap (.030") (.762 mm) and install the spark plug in the engine. Tighten the spark plug to 21 foot pounds (28 Nm) of torque. 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.

STANDARD PLUG

OHV

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, 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 OR 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 by adding Tecumseh's fuel stabilizer, part number 730245, to the gasoline. Fuel stabilizer is added to the fuel tank or storage container. Always follow the mix ratio found on the stabilizer container. Run the engine at least 10 minutes after adding

the stabilizer to allow it to reach the carburetor.

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 by 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 bowl drain (if equipped) which is located on the bottom of the carburetor bowl. On carburetors without a bowl 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 can 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. See "Oil Change Procedure"

on page 3.

Oil Cylinder Bore

1. Disconnect the spark plug wire and ground the spark plug wire to the engine. Remove the spark plug and put a 1/2 ounce (15 ml.) of clean engine oil into 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, head,

cylinder cooling fins, carburetor, governor levers and linkage.

CHAPTER 2 AIR CLEANERS

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 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

paper-type air filter system. A polyurethane pre-

cleaner or a flocked screen may be used with the main

filter. Snow King® engines do not use an air filter due

to the clean operating environment and to prevent filter

freeze-up.

Extremely dirty conditions may require more frequent

filter cleaning or replacement.

COVER

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

FOAM

ELEMENT

OPERATION

The air cleaner cover allows access to the air filter

element(s) and prevents large particles from entering

the filter body. Air is filtered through the pre-cleaner

or flocked screen if equipped, and the polyurethane

or paper filter element. Pre-cleaners or flocked

screens provide more air cleaning capacity.

In Tecumseh's Kleen Aire® system, air is drawn in

through a rotating screen or recoil housing to be

centrifugally cleaned by the flywheel before the air

enters the air filter.

COMPONENTS

The cover holds the filter element and prevents large

debris from entering the filter body.

The polyurethane wrap pre-cleaner is used on XL

or XL/C engine models with paper filter elements.

The paper or polyurethane filter element is the main

filter to trap dust and dirt. Dry-type paper elements

are pleated paper for increased surface area and

rubberized 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.

AIR CLEANER

BODY

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

FLOCKED SCREEN

COVER

POLYURETHENE

WRAP

PAPER

ELEMENT

AIR CLEANER

BODY

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 filter. A dirt restricted or an oil

soaked filter will cause noticeable performance problems. A polyurethane filter may be cleaned following the

service procedure listed under "Service" in this chapter. A paper-type air filter should only be replaced. A

paper-type filter cannot have an oil film present on the paper. Follow the procedure listed in the "Service"

section of this chapter for filter replacement or cleaning.

SERVICE

Service on the polyurethane filter element (cleaning and oiling) is recommended every three (3) months or

every twenty five (25) operating hours, whichever comes first. Extremely dirty or dusty conditions may require

daily cleanings.

The paper filter element should be replaced once a year or every 100 operating hours, more often if used in

extremely dusty conditions.

NOTE: NEVER RUN THE ENGINE WITHOUT THE COMPLETE AIR CLEANER ASSEMBLY INSTALLED ON

THE ENGINE. ALWAYS REPLACE THE FILTER ELEMENT WITH THE PROPER TECUMSEH ORIGINAL

REPLACEMENT PART.

DISASSEMBLY PROCEDURE

1. Unlock the tabs or remove the screws or wing

nuts 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 are to 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).

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 reverse procedure for reassembly. When

installing the polyurethane pre-cleaner, make

sure the seam is installed to the outside to

prevent gaps between the paper element and

the pre-cleaner.

KLEEN-AIRE

ENTRANCE

COVER

FOAM

FILTER

KLEEN-AIRE

ENTRANCE

FILTER A

(FOAM)

WING NUTS

COVER

GASKET

NUTS

FILTER B

BODY

GASKET

FLOCKED SCREEN

GASKET

Polyurethane-Type Filter Element or pre-cleaner

This type of air filter or pre-cleaner can be serviced when restricted with dust or dirt. Wash the filter or pre-

cleaner in a detergent and water solution until all the dirt is removed. Rinse in clear water to remove the

detergent solution. Squeeze the filter or pre-cleaner (do not twist) to remove the excess water. Wrap the filter

or pre-cleaner in a clean cloth and squeeze it (do not twist) until completely dry.

On the polyurethane filter only, re-oil the filter by applying engine oil and squeezing it vigorously to distribute

the oil. Roll the filter in a cloth and squeeze it (do not twist) to remove the excess oil. The pre-cleaner must not

be oiled.

Clean the air cleaner housing and cover being careful not to allow dirt to fall into the carburetor or intake 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. Replacement filters are available at any authorized Tecumseh Service Outlet. Be sure to use new

filter nuts or seals for the air cleaner studs if supplied with the new filter (diag. 5).

Flocked Screen

A flocked screen may be cleaned by blowing compressed air through the screen from the backside. If the

screen cannot be cleaned with this procedure, it should be replaced with a new screen.

COVER

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

AIR CLEANER

BODY

FOAM

ELEMENT

FLOCKED SCREEN

COVER

POLYURETHENE

WRAP

PAPER

ELEMENT

AIR CLEANER

BODY

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

CHAPTER 3 CARBURETORS AND FUEL SYSTEMS

GENERAL INFORMATION

Tecumseh overhead valve engines use float type carburetors. Float type carburetors use a hollow float to

maintain the operating level of fuel in the carburetor.

The float type carburetor will have a fuel enrichment system of either a primer or a manual choke to provide

easy cold engine starting. The carburetor fuel mixtures are either fully adjustable, partially adjustable, or

nonadjustable. Carburetor adjustments, cleaning, and related fuel system service is covered in this chapter.

Some Tecumseh engines utilize Walbro carburetors. Basic operation is very similar to the Tecumseh float style

carburetor.

Carburetors used by Tecumseh can be identified by a manufacturing number stamping on the carburetor 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 find

the correct carburetor part number is to use the

manufacturing number stamped on the carburetor and

convert this number to a service part number. In the

carburetor section of the Master Parts Manual or

Microfiche Catalog, a cross reference chart will

convert a carburetor manufacturing number to a

Tecumseh Service part number.

AL TERNATE LOCATION FOR MANUFA CTURING NUMBER

89 4F5

Complete carburetor replacement may be

accomplished by a standard service carburetor. A

standard service carburetor is a basic carburetor that

may require the use of original carburetor parts or

additional new parts to adapt to the specification. An

MANUF ACTURING NUMBER

CARBURETOR DATE CODE

instruction sheet is provided with the new service

carburetor or see SERVICE in this chapter.

OPERATION

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

starting device is operated to start the engine,

downward piston travel creates a low air pressure area

in the engine cylinder above the piston. Higher

pressure (atmospheric air) rushes into the engine to

fill the created 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 increased speed. The main nozzle and both idle

fuel discharge ports are supplying fuel due to the low

air pressure in the intake of the engine. A maximum

fuel flow through the carburetor orifices combined with

the reduced quantity of air that passes through the

carburetor, make a very 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. A fuel / air mixture is supplied through the primary idle-fuel discharge orifice during

idle.

CHOKE PLA TE

FLA T DOWN

During INTERMEDIATE engine operation, a second orifice is uncovered as the throttle shutter opens, and

more fuel mixture is allowed to atomize with the air flowing into the engine.

During HIGH SPEED engine operation, the throttle shutter is 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 the difference in the atmospheric 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 must be present

for the carburetor to operate properly (diag. 3).

Air is bled into the main nozzle through the air bleed

located in the air horn. This mixes fuel and air prior

to the fuel leaving the main nozzle. Atomization occurs

as the fuel mixture contacts the fast moving air stream

and the mist flows into the intake of the engine.

FUEL PRIMERS

TYGON TUBE

INTERNAL VENT

EXTERNAL VENT

Primers may be mounted remotely or as an integral

part of the carburetor. The basic function of the primer

is to supply an air pressure charge to the carburetor

main well or carburetor bowl to displace 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. 4 & 5).

Primers must be vented either internally through a

passage in the carburetor air horn prior to the venturi

or externally through a hole in the primer bulb. The

vent allows atmospheric air to enter the fuel bowl

during operation and to fill the primer bulb after the

primer bulb is released.

IMPULSE FUEL PUMPS

Impulse fuel pumps may either be mounted externally

onto the carburetor fuel inlet or remotely mounted.

This pump is 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 the 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).

A crankcase overfilled with engine oil can affect pump

operation.

PRIMER BULB

VENT

CRANKCASE PRESSURE

ATMOSPHERIC PRESSURE ACTING

ON DAMPING DIAPHRAGM FUEL FLOW

VALVE CLOSED

ATMOSPHERIC VENT

VALVE OPEN

FUEL SUPPLY

CRANKCASE SUCTION AND

FLOW DIRECTION ATMOSPHERIC PRESSURE ACTING ON DAMPING

DIAPHRAGM

PRIMER BULB

MAIN NOZZLE

MAIN JET

CARBURETOR FITTING

VALVE OPEN

DIAPHRAGM

FILTER

AIR BLEED

VALVE CLOSED

PULSE LINE TO CRANKCASE

SUCTION FUEL FLOW DIRECTION ATMOSPHERIC PRESSURE CAUSED FUEL FLOW

FLOAT STYLE CARBURETORS

A float is used to maintain the operating level of fuel

in the carburetor bowl. As the fuel is used by the

engine, the fuel level 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 level 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 and the fuel level in the

carburetor bowl remains constant (diag. 7). The float

height is set according to the service procedure.

THROTTLE SHUTTER

IDLE ADJUSTMENT

MAIN NOZZLE

IDLE AIR BLEED

MAIN ADJUSTMENT

MAIN AIR BLEED

CHOKE SHUTTER

INLET NEEDLE AND SEAT

FLOAT

CARBURETOR VISUAL IDENTIFICATION

Series1 Carburetors

Series 1 carburetors are used on some 4 - 7 model

overhead valve engines. This float style carburetor

has a smaller venturi than the Series 3 or 4 carburetor

and has no bosses on each side of the idle mixture

screw. The main and idle mixture may be fixed or

adjustable. A remote primer or choke may also be

used with this carburetor (diag. 8).

Series 3 & Series 4 Carburetors

Series 3 or 4 carburetors are generally used on 8

through 14 model 4-cycle engines. The quickest way

to identify these carburetors is by the presence of

bosses on each side of the idle mixture screw (diag.

9).

To determine whether the carburetor is a Series 3 or

Series 4, look at the throttle end of the carburetor.

Series 3 will have one throttle plate screw (diag. 10).

The Series 4 will have two throttle plate screws (diag.

11).

Series 6 Carburetors

Series 6 carburetors are used on 2 and 4-cycle

engines in the 3 to 6 model range. Series 6 uses a

simple fixed idle and fixed main fuel circuit. Series 6

carburetors are commonly used on rotary mower

applications. Series 6 are nonadjustable, with a

stepped primer bulb and a bowl prime system (diag.

12).

Series 7

Series 7 carburetors are totally nonadjustable. The

die cast carburetor body is similar in appearance

and slightly longer than the Walbro LMK body. The

choke shaft is made of a plastic material with an

internal slot to hold the choke shutter. The carburetor

base is flat to accept a Vector style bowl that is held

on with a wire bail. (diag. 13)

Series 8

Series 8 carburetors have both a fixed main and a

fixed idle circuit. These carburetors are totally

nonadjustable. This series of carburetor uses an

integral primer system like the Series 6. Distinguish

this carburetor from the Series 6 by the fixed idle jet

that appears as a screw just above the bowl on the

primer side. This fixed idle jet may also be capped.

(diag. 14)

CAPPED FIXED IDLE JET

CAP

Series 9

Series 9 carburetors are hybrid versions of the

Series 8. This carburetor uses a fixed idle jet and fixed

main fuel circuit. This carburetor is totally

nonadjustable. The bowl nut uses a ball plug on the

bottom to cover the center drilling. Also visible is a

plastic main fuel discharge nozzle in the venturi. The

Idle mixing well and jet will be visible but not machined

(diag. 15)

Series 10

This carburetor is for use on all season engine

applications. It is the equivalent of the series "8" with

the addition of a choke. It has a fixed main and idle

with a serviceable main nozzle and a primer assist,

with the added benefit of a choke for cold weather

starting.

MIXING WELL CAST BUT NOT MACHINED

IDLE JET CAST BUT NOT MACHINED

CHOKE PLATE

FLAT SIDE DOWN

Walbro Model LMK

OHV 15-17 models use this float-feed carburetor. The

carburetor is attached to the intake pipe using studs

that also fasten the air filter body. Walbro model and

manufacturing numbers are found on the throttle end

of the carburetor. This carburetor has a fixed,

nonadjustable main mixture jet.

Idle mixture screws were adjustable on early

production OHV15. This has since changed to a fixed

idle jet which may be capped for tamper resistance.

If no spring is visible, the jet is fixed. Servicing should

be done by a Authorized Tecumseh Dealer.

LOW IDLE MIXTURE SCREW MA Y BE ADJUSTABLE OR FIXED

TESTING

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 removing the spark plug. Install a commercially available

spark tester and check for spark. If the spark is bright blue and consistent, proceed to step 2. If no or

irregular spark see Chapter 8 under "Testing".

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

cylinder.

NOTE: Check plug for correct reach (diag.

17).

3. If the spark plug is dry, check for restrictions

in the fuel system before the carburetor. If the

spark plug is wet, continue with step # 7.

CHECK THE FUEL CAP FOR PROPER

VENTING. With a proper draining receptacle,

remove the fuel line clamp on the carburetor

fuel inlet and pull the fuel line off the fitting.

Examine the fuel flow with the fuel cap both

on and off the fuel tank.

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.

STANDARD

PLUG

OHV

4. 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.

5. If the fuel flow from the tank 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 Troubleshooting

chart to diagnose carburetor symptoms. Improper fuel flow indicates the fuel, fuel line, filter or tank

require cleaning or replacement.

6. Check the engine compression using a commercially available 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

Troubleshooting.

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, excessive choking or over priming,

improperly adjusted or defective carburetor. With the spark plug removed and a shop towel over

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 OVER.

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 try to start the engine.

9. If the engine floods and fails to start, the carburetor will require service. See the proceeding Carburetion

Troubleshooting chart for additional causes. If the carburetor is functioning properly the problem may

be ignition timing related. See Chapter 8 Ignition under Troubleshooting.

SERVICE

Carburetor Pre-sets and Adjustments

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. Start the engine and allow it to

warm to operating temperature. The carburetor can now be adjusted.

NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS.

Pre-sets and Adjustments (Tecumseh and

Walbro carburetors)

Turn both the main and idle mixture adjusting screws

in (clockwise) until finger tight if applicable.

NOTE: OVERTIGHTENING WILL DAMAGE THE

Engine Model Main Pre-set Idle Pre-set

All models with

float-type carburetors 1-1/2 turn 1 turn

Tecumseh Carburetors

TAPERED PORTION OF THE NEEDLE.

Now back the mixture screws out (counterclockwise)

to obtain the pre-set figure in the chart shown.

NOTE: SOME CARBURETORS HAVE FIXED IDLE

AND MAIN JETS. IDENTIFY THE SERIES OF

CARBURETOR USING THE VISUAL IDENTI-

FICATION IN THIS CHAPTER. IDLE MIXTURE

FIXED JETS APPEAR AS ADJUSTING SCREWS

WITHOUT TENSION SPRINGS AND ARE NOT

ADJUSTABLE.

All models with

diaphragm-type

carburetors 1 turn 1 turn

Walbro Carburetors

Carburetor Model

LMK Fixed 1 turn if

adjustable

or seated,

if fixed

Final Adjustments

Start the engine and allow it to warm up to normal operating temperature (3 - 5 minutes). Set the speed control

to the HIGH or FAST position, then turn the main mixture adjustment screw in (clockwise) slowly until the

engine begins to run erratic. Note the position of the screw. Now, turn the screw out (counterclockwise) until

the engine begins to run erratic. Turn the screw in (clockwise) midway between these two positions. This will

be the best setting.

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.

Identify the location of both HIGH and LOW speed adjustments, then locate the recommended HIGH and

LOW R.P.M. setting according to microfiche card # 30 and adjust the engine speed accordingly.

NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS.

TECUMSEH CARBURETORS

DUAL SYSTEM / SERIES "6"

NON-ADJUSTABLE

PRIMER NO CHOKE

FIXED HIGH AND LOW SPEED

SERIES "7"

MIXTURE

SERIES "3" & "4"

IDLE MIXTURE SCREW

MAIN MIXTURE SCREW

WALBRO

CARBURETOR

SERIES "8"

SERIES "9"

SERIES "10"

WALBRO LMK

CAPPED FIXED IDLE JET

NON-ADJUSTABLE

(ADJUSTABLE MAIN FOR

EXPORT)

NON-ADJUSTABLE

If further adjustment is required, the main adjustment should be made under a load 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. A few Tecumseh carburetors were built as air adjust idle system. If you have one, the adjustments

are reversed out for lean in for richer.

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.

CARBURETOR DISASSEMBLY PROCEDURE

NOTE : CARBURETORS THAT ARE EMISSION COMPLIANT (MANUFACTURING NUMBERS 5000 OR

GREATER) WITH FIXED IDLE OR MAIN JETS ARE TO BE REMOVED BY DEALERS ONLY FOR INSPECTION

AND CLEANING.

1. Note or mark the high and low mixture adjusting screws to aid in reassembly (if applicable). Remove

the high speed mixture screw, bowl nut, and float bowl. Remove the idle mixture screw assembly. On

Series 7 carburetors, release the wire retainer that retains the bowl and remove the bowl assembly. If

a screwdriver or similar tool is used to release the retainer, carefully move the retainer to prevent

bending of the wire.

2. Series 8 carburetors have a tamper resistant cap, over the fixed idle jet. (diag. 21). The cap is removed

by piercing it with an ice pick or similar instrument, then remove the jet for service, always replace the

cap.

3. Note the position of the spring clip on the inlet needle and float. Remove the float hinge pin with a

needlenose pliers. Some carburetors use a float dampening spring to aid the inlet valve to maintain a

steady position in rough service applications. Note the position of the hooks before removing the float

hinge pin (diag. 25). On Series 7 carburetors, grasp the crossbrace on the float with a needlenose

pliers and pull straight out to release the float hinge pin.

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

5. Remove the inlet needle seat using a wire or a paper clip with a 3/32" (2.38 mm) hook end (Tecumseh

carburetors only, Walbro model LMK uses a non-serviceable seat). Push the hook through the hole in

the center of the seat and pull out to remove it.

6. On Series 7 only, remove the main nozzle tube, "O" ring, and spring located in the center leg of the

carburetor bowl. Remove the bowl drain screw and gasket. Remove the spring, metering jet, and "O"

ring.

7. 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.

NOTE: MARK THE EDGES OF THE THROTTLE AND CHOKE SHUTTERS PRIOR TO DISASSEMBLY.

THE SHUTTERS HAVE BEVELED EDGES AND MUST BE INSTALLED IN THE ORIGINAL POSITION.

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. To remove the

choke shaft assembly on Series 7 or Walbro LMK carburetors, grasp the choke shutter with a pliers

and pull it through the slot in the choke shaft. Slide the choke shaft out of the carburetor body.

LONG END OF CLIP

CHOKE END

CLIP OPEN END OF CLIP

THROTTLE END

3/32"

(2.38 mm)

8. Remove the primer bulb (if equipped) by

grasping with a pliers and pulling and twisting

out of the body. Remove the retainer by prying

and lifting out with a screwdriver. Do not re-

use old bulb or retainer (diag. 28).

9. 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 and push down on the chisel

to pry the plug out of the hole (diag. 29).

NOTE: DO NOT REMOVE ANY BALL OR CUP PLUGS (diag. 29).

10. Note the direction of the inlet fitting. If necessary the inlet fitting can be removed by pulling with a pliers

or vise, do not twist. The fitting must be replaced. Tap a 1/4-20 thread inside the metal shank, use

1/4"-20 bolt and nut inserted into a 1/4" (6.350 mm) flat washer and 1/2" (12.700 mm) nut, thread the

bolt into the shank, and thread the nut down to pull out the shank.

11. The Walbro LMK carburetor main fuel jet can be removed only if the jet is damaged or if a high altitude

jet is needed to be installed. To remove place the carburetor firmly in a soft jawed vice. Using a punch

the same size or slightly smaller than the jet, drive the jet through and into the center leg. Insert the

high altitude jet in the same hole. Using a punch slightly larger than the diameter of the new jet, tap it

into place flush with the outside of the center leg casting (diag. 31).

SMALL CHISEL

PRY OUT PLUG

DO NOT ALLOW CHISEL POINT TO STRIKE CARBURETOR BOD Y OR CHANNEL REDUCER

PIERCE PLUG WITH TIP

WELCH PLUG T O BE REMOVED

SMALL CHISEL

BRASS OR BALL PLUG

ABOUT 1/8" (3.175 mm) WIDE

BALL PLUG

Impulse Fuel Pump

The valve type impulse pump can be serviced using

the following procedure.

1. Remove the old filter on the back of the pump

body if applicable.

2. Note or mark the pump body alignment, remove

the four screws and disassemble the pump.

3. Remove the gaskets, diaphragms, old valves

and spring bearing from the spring.

4. Clean the body parts with solvent.

5. Install new valves with the face of the valve

facing the raised portion of the passage. After

installation, cut off the extended portion of the

valves.

DO NOT REMOVE PLUGS

IDLE FUEL PASSAGE REDUCTION ROD INSIDE

ATMOSPHERIC VENT

HIGH SPEED JET

WALBRO LMK SERIES

6. Install the diaphragms against the center portion

of the body with the gaskets against the outside

covers. The parts can only can be assembled

one way without damage.

7. Install the spring bearing on the new spring and

place into position.

8. Assemble the body sections, install the retaining

screws, and torque the screws to 12 - 16 inch

pounds (1.36 - 1.81 Nm).

9. Install new filter in pump cavity if applicable.

1 - Body, Impluse

2 - Body, Pump

3 - Cover, Pump

4 - Bearing, Spring

5 - *Valve, Check (2)

6 - *Gasket, Pump Cover

7 - *Diaphragm, Pump (2)

9 - Screw, 1-1/4" (4)

10 - *Spring, Pressure

11 - *Filter, Air

FLOAT ADJUSTING PROCEDURE

All Tecumseh carburetors with an adjustable float

require the correct float height to achieve the proper

operation and easy engine starts. To check the float

FLOAT SETTING

FLOAT

FLOAT HINGE AND AXLE

setting, hold the carburetor in an upside down position.

Remove the bowl nut, float bowl, and "O" ring. Place

an 11/64" (4.36mm) diameter drill bit across the top

11 / 64" (4.36 mm)

of the carburetor casting on the opposite side and

parallel to the float hinge pin. 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

ADJUSTING T AB INLET NEEDLE

AND SEAT

small bladed screwdriver to bend the tab.

If float sticking occurs 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 inch in either direction,

then return the bowl to its original position and tighten the bowl nut.

THE TECUMSEH SERIES 7 AND THE WALBRO MODEL LMK CARBURETOR HAVE A FIXED AND

NONADJUSTABLE FLOAT HEIGHT.

Inspection

After careful disassembly of the carburetor and the removal of all non metallic parts, all metallic parts should

be cleaned with solvent, or commercial carburetor cleaner, no longer than 30 minutes. Wearing eye protection,

use compressed air and soft tag wire or monofilament fishing line to clean internal carburetor passages. To

perform a proper carburetor rebuild, the welch plugs must be removed to expose the drilled passages.

Throttle and Choke

Examine the throttle and choke shaft, and carburetor body at the bearing points and holes into which the

linkage is fastened, and replace if worn or damaged. Any excessive wear in these areas can cause dirt to

enter the engine and cause premature wear. If dust seals are present, check the seal condition and the correct

placement next to the carburetor body.

Idle and High Speed Mixture Adjusting Screw

Examine the idle mixture needle tip and tapered

surface for damage. The tip and tapered surface of

the needle must not show any wear or damage. If

either is worn or damaged, replace the adjusting

needle. Tension is maintained on the screw with a

RET AINER NUT

"O" RING

BRASS WASHER SPRING

coil spring. Replace the O ring seal if removed (diag.

34).

Examine the tapered surface of the high speed mixture

needle. If the tapered surface is damaged or shows

wear, replace the needle.

HIGH SPEED ADJUSTMENT SCREW

Fuel Bowl Retaining Nut

The bowl nut contains the passage through which fuel

is delivered to the high speed and idle fuel system of

the carburetor. If a problem occurs with the idle system

of the carburetor, examine the small fuel passage in

the annular groove in the bowl nut. This passage must

be clean for the proper transfer of fuel into the idle

metering system.

Bowl nuts that are used on adjustable main, float style

carburetors may use either one or two metering ports.

This difference relates to calibration changes of the

carburetor, depending on the application (diag. 35).

FUELMETERING PORT

ONE-HOLE TYPE

IDLE FUEL TRANSFER PASSAGE

TW0-HOLE TYPE

FUELINLET

NOTE: DO NOT INTERCHANGE BOWL NUTS.

The fuel inlet ports must be free of any debris to allow

proper fuel flow.

Fuel Bowl, Float, Needle and Seat

NOTE: To prevent damage to the float bowl on Series 7 carburetor, pull straight up with a needle nose pliers in

the pocket closest to the main fuel well (diag. 37).

The float bowl must be free of dirt and corrosion. Clean the bowl with solvent or carburetor cleaner (soak 30

minutes or less).

Examine the float for cracks or leaks. Check the float hinge bearing surfaces for wear, as well as the tab that

contacts the inlet needle. Replace any 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 and replacement is recommended. Only the

inlet needle is serviceable on the Walbro model LMK carburetor.

FLOAT HINGE PIN

NEEDLE & SEA T

SEA T RET AINING RING

BOWL RETAINER

CHOKE SHAFT

CHOKE DUST SEAL

CHOKE RETURN SPRING

CHOKE SHUTTER

FUEL FITTING INLET NEEDLE

FLOAT

SERIES 7

FLOAT

MAIN NOZZLE EMULSION

"O" RING

POSITIONED IN GROOVE

SPRING

IDLE RESTRICTION

BOWL

'O' RING

MAIN JET

MAIN JET SPRING

GASKET

BOWL DRAIN

THROTTLE SHAFT

THROTTLE DUST SEAL

THROTTLE RETURN SPRING

IDLE SPEED SCREW

WELCH PLUG

IDLE MIXTURE SCREW

TENSION SPRING

THROTTLE SHUTTER

SCREW

FLOAT SHAFT

"O" RING

THROTTLE SHUTTER

THROTTLE SHUTTER SCREW

PRIMER BULB/ RET AINER RING

PRIMER BULB FIL TER

A TMOSPHERIC VENT WELCH PLUG

FLOAT

SEA T

NEEDLE

SPRING CLIP

HINGE PIN

"O" RING

NOZZLE

"O" RING

POSITIONED IN GROOVE

BOWL

WASHER

JET/BOWL NUT

SERIES 8, 9 & 10

THROTTLE SHAFT & LEVER

THROTTLE RETURN SPRING

DUST SEAL WASHER DUST SEAL

FUEL FITTING

"O" RING

SEAT AND CLIP INLET NEEDLE

SPRING CLIP

FLOAT SHAFT

FLOAT BOWL

BOWL NUT WASHER

BOWL NUT

WALBRO LMK SERIES 6

39 40

FLOAT BOWL

BOWL NUT WASHER

HIGH SPEED BOWL NUT

ASSEMBLY PROCEDURE

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 the size of the plug hole, 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 fingernail

polish (diag. 41).

NEW WELCH PLUG

FLAT END PUNCH

SAME OR LARGER DIAMETER OF PLUG HOLE

Throttle Shaft and Plate

When reassembling Tecumseh or Walbro carburetors,

it is important that the lines, lettering, or numbers on

the throttle plate are facing out when in the closed

position. If the throttle plate has only one line, this

line should be positioned in the 3 oclock position on

Series 3, 4, and 7 carburetors, and at the 12 o'clock

position on Series 1, 6, 8, 9 carburetors. (diag. 42 &

43).

Test the operation of the throttle and return spring if

equipped. If binding occurs, correct by loosening the

screws and repositioning throttle plate.

Always use a new screw(s) when reinstalling the

throttle shutter to prevent the screws from loosening

and being drawn into the engine. New Tecumseh

screws are treated with dry-type adhesive to secure

them in place.

NOTE: NEVER REUSE OLD SCREWS.

On Walbro LMK and Series 7 carburetors, install the throttle return spring on the throttle shaft with the squared end up. Slide the foam dust seal over the spring. Insert the throttle lever assembly into the carburetor body with both tangs of the return spring on the left side of the center boss (viewed from throttle end) and the flat side of the shaft toward the carburetor mounting flange. Install the throttle shutter to the throttle shaft using notes or marks to place the shutter as originally found (Series 7 must have the line on the shutter at the 3 o'clock position) (diag. 44).

THROTTLE PLATE

THROTTLE LEVER

TWELVE

O'CLOCK

POSITION

THREE

O'CLOCK

POSITION

DUST SEALS

Always use new throttle shutter screws when reinstalling. Install the screws so they are slightly

loose. Apply light downward pressure on the throttle shaft and rotate it clockwise to seat the throttle shutter in the bore, then tighten the throttle shutter screws. Check for binding by rotating the throttle shaft. If necessary , adjust the throttle shutter by loosening and repositioning the shutter, then retighten the screws (diag. 45).

THROTTLE LEVER

THROTTLE PLATE

SERIES 7

WALBRO LMK SERIES

Choke Shaft and Plate

The choke plate is inserted into the air horn of the

carburetor in such a position that the flat surface (if

applicable) 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. 46).

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 cutout

position of choke shutter if applicable.

On Walbro LMK and Series 7 carburetors, install the

choke return spring on the choke shaft with the

squared end up and hooked into the notch in the plate.

Work the dust shield up around the spring and insert

the choke shaft into the carburetor body. Rotate the

shaft counterclockwise until the tang on the spring

rests against the left side of the center boss on the

carburetor body (viewed from choke end) . Rotate the

choke shaft approximately 1/4 turn counterclockwise

and insert the choke shutter into the slot in the choke

shaft. Make sure the tabs on the shutter lock the choke

shaft between them. Rotate the shaft and check for

binding, the choke must return to the open position

when released (diag. 47).

CHOKE PLA TE

PRESS IN P AR TIALLY THEN APPLY LOCTITE

FLA T DO WN

SOME INLET FITTINGS

STRAINER

SPRING HOOKUPS

Fuel Inlet Fitting

When installing the fitting, insert the tip into the

carburetor body. 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. Press

it in until it bottoms out (diag. 48).

High and Low Speed Adjusting Screw, Main

Nozzle

When reassembling, position the coil spring on the

adjusting screws, followed by the small brass washer

and the O ring seal. Turn the high speed adjustment

screw into the bowl nut and the low speed mixture

screw into the carburetor body (diag. 49).

Some carburetors may have a fixed main mixture or

both a fixed idle mixture and main mixture, and are

not adjustable.

On Series 7carburetors, place the main nozzle spring

into the main nozzle cavity. Apply oil to the main nozzle

"O" ring and push the main nozzle into the cavity

with the "O" ring end in first.

Next install the "O" ring in the main jet cavity. Place

the spring over the shoulder on the main jet and push

the jet into the cavity with the main jet toward the "O"

ring. Place a new gasket on the drain screw and

tighten in position (diag. 50).

On Walbro LMK carburetors, the main jet can be

replaced by pressing it into the center leg of the

carburetor until flush. (diag. 31 page 15).

NOTE: FOR HIGH ALTITUDE JETTING, CONSULT

BULLETIN 110.

RET AINER NUT

FLOAT HINGE PIN

NEEDLE & SEA T

SEAT RETAINING RING

"O" RING

BRASS WASHER

SPRING

HIGH SPEED ADJUSTMENT SCREW

FLOAT

MAIN NOZZLE EMULSION

"O" RING POSITIONED IN

GROOVE

SPRING

IDLE RESTRICTION

BOWL

"O" RING

MAIN JET

MAIN JET SPRING

GASKET

BOWL RETAINER

BOWL DRAIN

Inlet Needle and Seat

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 5/32" (3.969 mm) flat punch, making

sure it is firmly seated (diag. 51). On Series "7"

carburetors, install the seat retainer into the cavity

and push it down using the flat punch until it contacts

the seat.

PUSH IN UNTIL SEAT RESTS ON BOD Y SHOULDER

IF Y OUR CARBURET OR HAS A STEEL SEAT RETAINING RING RE-INTSALL AFTER SEA T INSTALLATION

INLET NEEDLE SEATS AT THIS POINT

5/32" (3.969 mm) FLA T PUNCH

SEAT

INSERT THIS F ACE FIRST

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 choke or air filter end

of the carburetor as shown (diag. 52).

Float Installation

On Series 7 carburetors, slide the hinge pin into the

hinge on the float. Position the needle into the fuel

inlet and snap the float pin into the tabs on the float

bowl. Float height is not adjustable.

On Series 7 carburetors and the Walbro LMK, reinstall

the inlet needle on to the float and place it into the

carburetor (diag. 53).

1. When rebuilding a carburetor with a clip on

the needle, position carburetor float side up

for assembly.

2. Place the inlet needle and spring clip onto

the float as shown. The long end of the spring

clip must point towards the choke end of the

carburetor. This will ensure that the inlet

needle will move up and down in a straight

line (diag. 53).

3. To set the proper float height on carburetors

except Series 7 and Walbro LMK, see

adjusting procedure.

LONG END OF CLIP

Points toward chok e end

CHOKE END

SERIES 7 WALBRO / LMK

LONG END OF CLIP Points toward choke end

CLIP OPEN END OF CLIP

THROTTLE END

CLIP

OPEN END OF CLIP

4. Some Tecumseh float style carburetors have

a damper spring which is installed as shown

in diag. 55.

POINTS TOW ARD THE CHOKE END

Fuel Bowl And Bowl Nut

Whenever a carburetor bowl is removed for service,

the fuel bowl O ring (or gasket on Series "7") and

the bowl nut washer must be replaced. For easier

installation, lubricate the O ring with a small amount

oil.

Installing the Float Bowl

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

bowl 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.

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. 57).

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 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.

DETENT

CRANKCASE PRESSURE

ATMOSPHERIC PRESSURE ACTING

ON DAMPING DIAPHRAGM FUEL FLOW

VALVE CLOSED

ATMOSPHERIC VENT

VALVE OPEN

FUEL SUPPLY

CRANKCASE SUCTION AND

FLOW DIRECTION ATMOSPHERIC PRESSURE ACTING ON DAMPING

DIAPHRAGM

CARBURETOR FITTING

VALVE OPEN

DIAPHRAGM

FILTER

AIR BLEED

VALVE CLOSED

PULSE LINE TO CRANKCASE

SUCTION FUEL FLOW DIRECTION

ATMOSPHERIC PRESSURE CAUSED FUEL FLOW

If the flow is erratic or intermittent, the pump needs

repair or replacement.

Primer Bulb

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. 58).

Final Checks

Before reinstalling a newly overhauled 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.

CHAPTER 4 GOVERNORS AND LINKAGE

GENERAL INFORMATION

Tecumseh 4 cycle engines are equipped with mechanical type governors. The governors function is to maintain

a R.P.M. setting when engine loads are added or taken away. Mechanical type governors are driven off the

engines camshaft gear. The governor follower arm rests on the center of the governor spool on center force

governors, and off to one side on other governor systems. Changes in engine R.P.M. cause the governor lever

to move the solid link that is connected from the governor lever to the throttle in the carburetor. The throttle is

opened when the engine R.P.M. drops and is closed as an engine load is removed.

This chapter includes governor assembly linkage illustrations to aid in governor or speed control assembly.

OPERATION

As the speed of an engine increases, the governor

weights on the governor gear move outward by

centrifugal force. The shape of the governor weights

force the governor spool to lift. The governor rod

maintains contact with the governor spool due to the

governor spring tension. The governor rod rotates

causing the attached outer governor lever to push 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. The governor rod rotates and the

solid link moves the throttle to a more open position

(diag. 1).

THROTTLE

GOVERNOR GEAR

SPRING

GOVERNOR SHAFT

WEIGHTS

GOVERNOR SPOOL

TROUBLESHOOTING

Engine operation problems where the governor is suspected to be the cause may actually be the result of

other engine system failures. 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 must be corrected

immediately before serious engine damage occurs. Use the applicable following procedure to diagnose a

suspected governor failure.

ENGINE OVERSPEEDING

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

2. Check the condition of the external governor shaft, linkage, governor spring, and speed control assembly

for breakage 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 in one position 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 "Service"

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 governor adjustment, check the engine R.P.M. found 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 governor shaft or linkages for binding, wear, or improper hookup. Check the governor

spring for adequate tension or damaged condition. Repair or replace as necessary.

SERVICE

GOVERNOR ADJUSTMENT

With the engine stopped, loosen the screw holding the governor lever to the governor shaft clamp. Push the

governor lever to move the carburetor throttle plate to the wide open position. Rotate the governor clamp

counterclockwise on all overhead valve engines covered in this manual. Hold the lever and clamp in this

position while tightening the screw (diag. 2).

PUSH LEVER TO WIDE OPEN THROTTLE

GOVERNOR CLAMP SCREW

TURN CLIP COUNTERCLOCKWISE ON ALL VERTICAL SHAFT ENGINES EXCEPT VLV & VLXL. CLOCKWISE ON ALL HORIZONTAL SHAFT ENGINES EXCEPT OHH,OHSK 50,55 & OHM, OHSK 110,120.

THROTTLE LINK

GOVERNOR

LEVER

GOVERNOR

ROD

GOVERNOR

CLAMP

SCREW

YOU MUST USE THIS

LINK POSITION

ROTATE LEVER

& ROD

COUNTER-

CLOCKWISE

OHH SERIES - NEW STYLE

THROTTLE PLATE

THROTTLE OPEN

(PUSH COUNTER-

CLOCKWISE)

THROTTLE

PLATE

(TOP VIEW)

THROTTLE OPEN (PUSH COUNTERCLOCKWISE)

STANDARD LOCATION

GOVERNOR LEVER

GOVERNOR SCREW

GOVERNOR ROD

GOVERNOR CLAMP

ROTATE CLAMP COUNTERCLOCKWISE

OHH SERIES - OLD STYLE

GOVERNOR GEAR AND SHAFT SERVICE

After the cylinder cover is removed from the engine, the governor spool, gear, or governor shaft can be

removed. On some governor assemblies, the retaining ring must be removed to allow the spool or gear to

slide off the shaft. Other governor shafts use an upset to hold the governor spool on. If the gear requires

replacement, the governor shaft will have to be removed.

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 (diag. 4).

NOTE: DO NOT TWIST THE SHAFT WHEN

REMOVING. THE SHAFT BOSS MAY

BECOME ENLARGED AND THE PRESS FIT

WILL NOT SECURE THE NEW GOVERNOR

SHAFT.

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

and washer on the shaft. Start the shaft into

the hole with a few taps from a soft faced

hammer.

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

supporting the area below the shaft boss.

Press the shaft in until a part # 670297

(.0125" / .3175 mm) shim just becomes snug

(.010" - .020" / .254-.508 mm clearance)

(diag. 5).

GEAR

SHIM

WASHER

SHAFT BOSS

670297 (modified)

Governor Shaft Replacement, Retaining Ring Style

1. Remove the retaining ring, spool, gear assembly, and washer(s).

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 NOT TWIST THE GOVERNOR SHAFT WHEN REMOVING. THE SHAFT BOSS MAY

BECOME ENLARGED AND THE PRESS FIT WILL NOT SECURE THE NEW GOVERNOR SHAFT.

3. Start the new shaft into the shaft boss by tapping with a soft faced hammer.

4. Refer to the chart at right for the proper shaft exposed length from the mounting surface. Add a drop

of red Loctite 271 and press the governor shaft to the proper depth using a press or a vise. Wipe the

extra Loctite off after installation.

5. Reassemble the washer (s), governor gear, and spool followed by the retaining ring.

ENGINE MODEL EXPOSED SHAFT LENGTH

OHH/OHSK50-70 1.319" - 1.334"

OVRM (33.502 - 33.883 mm)

OHM 1.085" - 1.100"

OHSK80-130 (27.559 - 27.940 mm)

OVM

OVXL 1.350" - 1.365"

OHV (34.290-34.671 mm)

GEAR ASSY.

OVRM TYPE I

RETAINING RING

SPOOL

RETAINING RING

(GOV.)

WASHER

SHAFT

SERVICED AS ASSEMBLY

SPOOL

UPSET

SHAFT

GEAR ASSY.

(GOV.)

WASHER

OVRM TYPE II

RETAINING RING

SPOOL

WASHER

RETAINING RING

GEAR ASSY.

(GOV.)

WASHER

SPACER

SHAFT

OHH / OHSK50-70

MEDIUM FRAME

SPOOL

SHAFT

GEAR ASSY. (GOV.)

WASHER

OVM / OHV / OHM

SPOOL WASHER

RETAINING RING

GEAR ASSY. (GOV.)

WASHER

SPACER NOTE; SPACER MAY BE PART OF THE GEAR ASSEMBLY.

SHAFT

OHSK80-130

Speed Controls And Linkage

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 governor spring is connected between the speed control lever and the governor lever. Vertical shaft

engines may use an adjustable intake pipe mounted speed control bracket located above the carburetor, or a

vertical or horizontal control mounted on the side of the engine. The ignition ground out terminal, idle R.P.M.

and high speed R.P.M. adjustment screws may be located on the speed control bracket.

The adjustable speed control bracket which is

mounted on the intake pipe must be aligned properly

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 show common linkage hookup

arrangements. 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 contact a local Tecumseh dealer for the correct

R.P.M. settings for the engine model and specification.

NOTE: RPM SETTINGS CAN ALSO BE FOUND ON

THE COMPUTERIZED PARTS LOOK UP SYSTEMS.

HIGH SPEED STOP

OHH REMOTE SPEED CONTROL

The engine and equipment control must be adjusted

to allow the engine control lever to touch the high

speed stop when the equipment control is set in the

"highspeed" or "fast" position. Loosen the bowden wire

clamp, place the equipment control to the "fast"

position, move the engine control lever to contact the

high speed stop, and hold the lever in this position

while tightening the bowden wire clamp.

OHH GOVERNED IDLE SPEED CONTROL

This control is adjusted by bending the tabs on the control bracket to achieve the correct idle speed and high

speed. When the engine is running, the governor controls both the idle and the high engine speed. In order for

the governor to respond properly to a crankshaft load at engine idle, the idle speed screw on the top of the

carburetor must be set 600 RPM lower than the governed idle speed. Use the following procedure to set the

engine speeds (diag. 14 & 16).

1. Check to find the correct engine speeds found on microfiche card # 30 or using the Computer Parts Look-

up System.

2. Start and allow the engine to run ( 3-5 minutes) before beginning adjustments. Place the control knob in

the lowest engine speed position. Use a Vibra-Tach or other tachometer to set the non-governed idle

speed (600 RPM lower than the governed idle speed) by pushing the bottom of the governor lever away

from the control bracket so the throttle lever contacts the idle speed screw and hold the lever in this

position. Turn the idle speed screw clockwise to increase or counterclockwise to decrease engine idle

speed.

3. Allow the governor to control the throttle. Use a Vibra-Tach or other tachometer and bend the tab as

shown to achieve the specified governed idle speed.

4. Slide the control knob to the high speed position and bend the tab as shown to achieve the specified

governed high engine speed.

NOTE: Early production OHH engines did not have governed idle, set only the idle crack screw and high

speed governor stop.

WINTER APPLICATION CONTROL

GOVERNED IDLE LINK AND ADJUSTMENT

HIGH SPEED ADJUSTMENT

BEND T O ADJUST SPEED DECREASE INCREASE

OHH REMOTE & MANUAL

GOVERNOR SPRING

OHH RV CONTR OL

GOVERNED IDLE LINK

T-10THROTTLE CRACK SCREW

GOVERNED HIGH SPEED ADJUST

OHH FIXED SPEED

THROTTLE CRACK SCREW

CORRECT BUSHING INSTALLATION DEEP SIDE HERE

HIGH SPEED PIN POSITION

INCREASE DECREASE

GOVERNED IDLE TAB

LOW SPEED TAB

HIGH SPEED ADJUST

T-10

BEND

OH / OHSK CONTROL

HIGH SPEED TAB

GOVERNED HIGH SPEED ADJUST

1716

NOTE: ON REMOTE CONTROL THIS WILL NOT BE PRESENT

GOVERNED IDLE SCREW

OHSK / OHM CONTROL

HIGH SPEED ADJUST

LOW SPEED ADJUST

OVRM OVRM

DECREASE

INCREASE

OVRM SNAP IN CONTROL

GOVERNED IDLE ADJUST

HIGH SPEED ADJUST

OVM / OVXL GO VERNOR OVERRIDE

DETENT BEARING PLATE

BUSHING

LOCK NUT

ADDITION BOWDEN WIRE BRACKET

WAVE WASHER

CONTROL LEVER

NOTE: THIS CONTROL IS STANDARD ON SERVICE ENGINES AND IS OPTIONAL TO CUSTOMERS

CONDUIT CLIP

SCREW

CONVERSION TO REMOTE CONTROL

GROUNDING TERMINAL

WASHER

OHV11 - 17 SPEED CONTROL

SPEED CONTROL BRACKET

CONTROL KNOB

Remove the manual control knob by squeezing together with a pliers or prying with a screw driver. Remove

the air cleaner cover and air cleaner element to gain easier access to the speed control lock nut that holds the

control levers together.

Remove the 3/8" (9.525 mm) locknut, bushing, wave washer, control lever, and the detent bearing plate.

Reassembly of REMOTE control.

Discard the detent bearing plate and in its place install the washer with the smaller I.D. from the new parts bag.

Install the lever over the post making sure that the end of the lever is in the slot of the control.

Place the other washer with the large I.D. from the parts bag next to lever, then the bushing. The smaller side

of the bushing goes towards the lever and fits inside of the lever and the washer.

Discard the wave washer.

Install the lock nut.

Check the alignment of the lever, bushing and washers to ensure that everything is aligned properly and

torque the lock nut to 20 in. lbs. (2 Nm).

The control lever should move freely.

This engine speed control is set up with the "stop in the control". If a remote stop is desired remove and

discard the short green wire that runs from the speed control grounding terminal (to the remote grommet stop

blade). Reinstall the blade and screw. It will now be necessary to run a grounding wire to a remote grounding

switch in order to stop the engine.

A remote grounding switch can be added to the engine at this terminal as well, thus allowing the engine to be

stopped at either the stop in the control or the remote grounding switch.

OVM, OVXL, OHV VERTICAL SPEED

CONTROL

This remote speed control may have governed idle, a

choke override, and the option of an ignition remote

stop terminal block.

The speed control is adjusted to the equipment throttle

control by aligning the slot in the speed control lever

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" (1.02 - 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.

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 (away from the control) to

increase engine R.P.M.

Throttle plate alignment on all models with speed

controls mounted on intake manifold. This adjusts

choke in control as well (diag. 12 on page 25).

DECREASE INCREASE

HIGH SPEED

ADJUSTING LEVER

BEND

ADJUST

HIGH

SPEED

IDLE ADJUSTING

SCREW

CHOKE

HOOKUP

HIGH SPEED

ADJUSTMENT

TAB

THROTTLE

LINK HOOKUP

.040 - .070

(1.02 - 1.778 mm)

GAP LOCATION

CHOKE

ADJUSTING

TAB

CONTROL LEVER

HIGH SPEED

PIN POSITION

25OHV VERTICAL CONTROL

IDLE SPEED

SCREW

OHV 11-17 HORIZONTAL SPEED

CONTROL

This speed control is adjusted to the equipment throttle

control by aligning the slot in the speed control lever

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" (1.02 - 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.

NOTE: Assure that the throttle cable has full travel

from wide open throttle to full choke. Hard starting

could result if the cable is not properly adjusted to

allow for full choke.

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.

ALIGNMENT

HOLE

TOOL #670326

OHV 11 - 17 HORIZONTAL CONTROL

LINKAGE BUSHING

CHOKE LEVER

AIR GAP

(.040 - .070")

(1.02 - 1.778 mm)

BEND TAB TO

ADJUST

OHV 11 -17 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. Make sure they are in good

condition and in place (diag. 27).

CHAPTER 5 RECOIL STARTERS

GENERAL INFORMATION

Recoil starters used on vertical shaft Tecumseh engines are top mount horizontal pull style. Horizontal shaft

engines use recoil starters which can be mounted to pull either vertically or horizontally. All recoil starters turn

the engine over by engaging a dog(s) into the starter cup attached to the engine flywheel. All starters are

spring loaded to retract the dog(s) when the engine speed exceeds the turning speed of the starter.

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 extend outward when the pulley rotation forces 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

starter 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 starter dog(s) disengages from the starter cup. The starter dog

spring(s) returns the starter dog(s) to the disengaged position. When the starter handle is released, the recoil

spring turns the starter pulley in the opposite direction to retract the starter rope.

COMPONENTS

ROPE

HANDLE

ST AR TER HOUSING

HANDLE

HOUSING

PULLEY AND REWIND SPRING ASSY.

ST AR TER DOG

DOG SPRING

WASHER

RET AINER

BRAKE SPRING

WASHER

SPRING PIN

DOG SPRING

RETAINER

BRAKE SPRING

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 apply to the 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. The rope ends should be cauterized by burning with a match and wiping the rope end with a

cloth while hot.

CAUTION: HANDLE MATCHES SAFELY TO

AVOID BURNS, AND EXTINGUISH

COMPLETELY BEFORE DISCARDING.

# 4 1/2 rope = 9/64" diameter (3.572 mm)

# 5 rope = 5/32" diameter (3.969 mm)

# 6 rope = 3/16" diameter (4.762mm)

ROPE RETAINER REPLACEMENT

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 STARTER (OHH, OVRM,

OHM, OHSK, OVM, OVXL, OHV), and

STAMPED STEEL STARTER

Disassembly Procedure

1. After removing the rewind assembly from the

engine blower housing, release the tension on

the rewind spring. Remove the starter handle

and carefully allow the rope to unwind into the

starter housing (diag. 4).

2. Remove the decal or plastic disc in the center

of the rewind.

3. Place a 1" (25.4 mm) deep well socket under

the retainer. Set the rewind on a bench,

supported on the socket.

4. Use a 5/16" (7.937 mm) or a [1/4" (6.35 mm)

punch for stamped steel] roll pin punch to drive

out the center pin. The stamped steel center

pin is driven out from the outside, the punch tip

must be angled inside the center hole. Move

the punch around while driving the pin to help

keep the pin straight.

ONE PIECE ROPE RETAINER

HANDLE

PULLEY AND REWIND SPRING ASSY.

ST AR TER DOG

LEFT-HAND KNOT

STAPLE

ROPE

ST AR TER HOUSING

DOG SPRING

WASHER

RET AINER

BRAKE SPRING

WASHER

SPRING PIN

CAUTION: THIS REWIND SPRING IS NOT

SECURED IN A CANISTER. PULLEY

BOSSES HOLD THE REWIND SPRING AND

COVER, AND CAN BE EASILY DISLODGED

DURING HANDLING.

5. Remove the brake spring, retainer, washers,

and pulley assembly (diag. 4).

Note: The starter dogs face out on the stamped

steel starter and the dogs face in on the stylized

rewind starter.

6. All components in need of service should be

replaced.

Assembly Procedure

1. Reverse the disassembly 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. 6 & 7)

2. Install a new recoil spring if necessary 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. 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.

ST AR TER HOUSING HANDLE

HANDLE INSERT

ROPE

PULLEY AND REWIND SPRING ASSY.

ST AR TER DOG

BRAKE SPRING

SPRING PIN

DOG SPRING

WASHER

RET AINER

WASHER

4. 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 NOT 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 housing.

5. Replacing rope 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.

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 handle or prying out the staple.

2. Untie the temporary 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.

HANDLE

PULLEY AND REWIND SPRING ASSY.

ST AR TER DOG

LEFT-HAND KNOT

STARTER HOUSING

ROPE

DOG SPRING

WASHER

RETAINER

BRAKE SPRING

WASHER

SPRING PIN

RET AINER WEDGE

ST ARTER HOUSING

ST ARTER PULLEY SPRING & COVER

DOG SPRING ST ARTER DOG

DOG RET AINER

4. Use a small Phillips screwdriver or similar tool

to pry the retainer legs apart and lift out the

retaining wedge.

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 necessary.

Assembly

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

2. Install a new recoil spring if necessary 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.

RETAINING WEDGE

(STEEL CLIP - NEW STYLE)

STARTER HOUSING

ST ARTER PULLEY SPRING & COVER

DOG SPRING ST AR TER DOG

3. Apply a small amount of lithium grease to the

inner bore of the center shaft.

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: Refer to Service Bulletin 122 for metal

locking tab.

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.

KEEPER SPRING STYLE STARTERS

Disassembly Procedure

1. Untie the knot in the rope and slowly release

the spring tension.

2. Remove the center screw, retainer (cam dog

on snow proof type), starter dog(s) and dog

spring(s), and brake spring (diag. 10).

3. Turn the spring and keeper assembly to

remove the pulley. Lift the pulley out of the

starter housing. Replace all worn or damaged

parts.

HANDLE

HANDLE INSERT

LEFT-HAND KNOT

ROPE

PULLEY

CAM DOG

WASHER

"STAMPED STEEL WITH ROLL PIN"

DOG RET AINER

ST AR TER HOUSING

REWIND SPRING AND KEEPER ASSY.

DOG SPRING

ST AR TER DOG

DOG RET AINER

RET AINER SCREW

BRAKE SPRING

SPRING PIN

Assembly Procedure

HOUSING

NOTE: This procedure covers three starters. Follow

illustration of your starter type as shown.

1. Place the rewind spring and keeper assembly

into the pulley. Turn the pulley to lock into

position. A light coating of grease should be

on the spring.

2. Place the pulley assembly into the starter

housing.

3. Install the brake spring, starter dog(s), and

starter dog return spring(s). The starter dog

spring(s) must hold the dog(s) in against the

pulley.

4. Replace the retainer cup (cam dog on snow

proof starter) and retainer screw. Tighten to

65 - 75 in. lbs. (7-8.5 Nm) 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"

(5.159 mm) drill bit. The center screw torque

on cast aluminum starters is 115 to 135 in.

lbs. (13-15 Nm) (diag. 11).

5. Tension 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.

HANDLE

BRAKE SPRING

RETAINER

"ST AMPED STEEL"

HANDLE

HANDLE INSERT

LEFT-HAND KNOT

ROPE

PULLEY

"STAMPED STEEL WITH ROLL PIN"

CAM DOG

WASHER

SPRING & KEEPER ASSY.

PULLEY

DOG SPRNG

RET AINER SCREW

CENTER PIN

ST AR TER HOUSING

REWIND SPRING AND KEEPER ASSY.

DOG SPRING

ST AR TER DOG

DOG RET AINER

RET AINER SCREW

BRAKE SPRING

SPRING PIN

HANDLE

DOG SPRING

RET AINER

BRAKE SPRING

"ALUMINUM HOUSING"

HOUSING

SPRING & KEEPER

PULLEY

DOG BRAKE WASHER

CAM DOG

CENTER SCREW

Stylized Starter (OHV 13.5 -17)

1. Remove the starter handle by first pulling a

length of rope out using the handle, tying a

temporary knot in the exposed rope, and

untying the knot in the handle.

2. Untie the temporary knot and slowly allow the

rope to fully retract into the starter housing

and the recoil spring to fully unwind.

3. Remove the nut (using a 10 mm socket) and

washers from the center leg of the recoil

housing. Slowly unwind the dog spring by

allowing the starter dog retainer to rotate.

4. Remove the starter dog retainer, starter dog

spring, brake spring, and starter dogs.

5. Remove the starter pulley.

CAUTION: THE REWIND SPRING IS NOT

SECURED IN PLACE. HOUSING BOSSES

HOLD THE REWIND SPRING, AND THE

SPRING CAN BE EASILY DISLODGED

DURING HANDLING.

6. Remove the starter rope from the pulley if

necessary.

Assembly

LEFT -HAND KNOT

ST AR TER HOUSING

REWIND SPRING

PULLEY

BRAKE SPRING ST AR TER DOGS

ST AR TER DOG SPRING

STARTER DOG RETAINER

WASHER

LOCKWASHER 6mm METRIC NUT

TYPE I

1. Replace the starter rope if removed by

inserting one end through the hole in the side

of the pulley and tying a left hand knot near

the rope end. Pull the knot into the squared

area and wind the rope counterclockwise

(viewed from the pulley bottom) on the starter

pulley.

2. Place the pulley on the housing center leg,

align the end of recoil spring and the notch in

the pulley and push down until seated.

3. Insert the starter dogs on the pulley pegs with

the flat side away from the pulley, place the

brake spring and starter dog spring on the

pulley. The starter dogs must be free to retract

into the pulley pocket.

4. Place the starter dog retainer on the center

leg, hook the end of the dog spring into the

hole in the retainer, press down and turn 1/2

a turn clockwise to line up the notches to the

starter dogs, add the nylon washer, metal

washer, lock washer, and hex nut. Tighten the

hex nut to 40 inch pounds (4.5 Nm) torque.

NOTE: Type II - Apply blue Loctite to the

center screw and torque to 70 in pounds

(8 Nm).

5. Wind the pulley counterclockwise 4-5 turns,

thread the rope through the starter housing

hole, and place a temporary knot in the rope

leaving at least one foot of rope length.

ST AR TER DOG

BRAKE SPRING

LOCKWASHER

TYPE II

ST ARTER HOUSING

SPRING AND KEEPER

PULLEY

ST ARTER DOG RET AINER SPRING

WASHER

ST ARTER DOG RET AINER

CENTER SCREW

6. Slide the starter handle on the end of the rope

and secure using a left hand knot. Remove

the temporary knot and allow the rope to

retract.

CHAPTER 6 ELECTRICAL SYSTEMS

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. A 120 volt 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 battery charge.

The starting circuit includes the battery, battery cables, starter or ignition switch, safety switches, starter solenoid,

and an electric starter motor.

The charging system consists of alternator charge coils, rectifiers or diodes, regulator, ignition switch, 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 closes the starting 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-drift spring holds the pinion in the

disengaged position (diag. 1).

BRUSHES

BRUSH SPRINGS

BRUSH CARD

HOUSING

SPRING RET AINER

RET AINER

SPRING

DUST COVER

LOCK NUT

BOL T

END CAP

GEAR

END CAP

WASHER

NUTS

ARMA TURE

THRUST

WASHER

ENGAGING NUT

CHARGING CIRCUIT

The charging system works independently of any

manual controls. The engine needs to be running to

produce an electric current flow. When a conductor

(alternating coils) cuts the magnetic field generated

by the magnets in the flywheel, a current is 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. waveform (diag. 2).

ROTATION OF FLYWHEEL

CONVERTING ALTERNATING CURRENT

TO 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.

BAND OR OTHER MARKING INDICA TES CA THODE END

3). A single diode makes use of only one half of the

A.C. signal and is known as HALF WAVE

RECTIFICATION (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.

+ VOL TAGE

HALF WA VE RECTIFIER

(SINGLE DIODE)

+ VOL TAGE

- VOL TAGE

A.C. INPUT

Full Wave Rectifier Bridge Rectifier

The full wave rectifier makes use of the entire A.C.

signal, converting it to D.C.

COMPONENTS

- VOL TAGE

+ VOL TAGE

- VOL TAGE

D.C . OUTPUT

FULL WAVE RECTIFIER

(BRIDGE RECTIFIER)

A.C. INPUT

BATTERY

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 the original equipment

manufacturers service manual for battery size,

capacities, and testing procedure.

A.C. INPUT

+ VOL TAGE

D.C . OUTPUT

- VOLTAGE

+ VOLT AGE (D.C.)

WIRING

The wires used in Tecumseh electrical 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 for leakage to "ground out" on the engine or frame. This is of

special concern when moisture or water is present.

WIRE GAUGE: The proper thickness of wire is

necessary in all electrical circuits. Wire diameter is

THE LARGER THE NUMBER THE SMALLER THE WIRE

measured in increments of gauge numbers. As the

gauge number of the wire increases, the wire diameter

decreases in size (diag. 6).

# 18

1. The starter circuit wiring must be rated at #6 or

lower gauge number.

2. The charging circuit wiring must be rated at #16

# 6

or lower gauge number (20 amp system requires

#14 or lower gauge number).

3. The magneto circuit wiring (ground circuit) must

be rated at #18 or lower gauge number.

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

Code Product

Yellow - Alternator A.C. Leads

Red - Alternator D.C. + Leads

Brown - Alternator 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

ALTERNATOR - 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.

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.

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. Silver, copper and gold are some of the

better known conductors.

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

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 terminals or 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 properly.*

*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 TO THIS

DATE. IF THE TRACTOR IS "CUTTING OUT" OR WILL NOT START, THIS IS AN AREA THAT SHOULD BE

CHECKED OUT.

TROUBLESHOOTING ELECTRICAL STARTER CIRCUIT FLOW CHART

Starter will not

Repair or

replace power

source

Is there power

Check wiring,

safety switches,

starter switch

turn

at the power

source?

connections,

YES

Intermittent

starter operation

Is power supplied to the

starter terminal?

YES

Starter turns at

low rpms or

stalls under load

Isolate engine

from the

equipment,

does engine

turn over?

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

Internal engine

failure repair or

replace engine

YES

Reinstall spark

plug, does

engine bind on

compression

stroke?

Repair or replace

equipment

causing

excessive

YES

Check valve lash.

Adjust if

necessary. Does

the engine turn

over without

binding now ?

Internal engine

failure repair or

replace engine

TROUBLESHOOTING ELECTRICAL CHARGING CIRCUIT FLOW CHART

Identify the charging system

used by model and

specification number or visually

checking the electrical plug

Consult the Mechanic's

Handbook or Electrical

Troubleshooting booklet for test

procedure for the charging

system used

Test for either AC 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

STARTING CIRCUIT

1. Check the power source using an electrical tester and following the tester's recommended procedure.

Make 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 120v A.C.) using a voltmeter.

CAUTION: FOLLO W ALL SAFETY PRECAUTIONS WHEN TESTING FOR A.C. V OL T A GE, 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. Check for proper lubrication (oil level and viscosity) and check

for electric 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 valve clearance is within the specifications, the camshaft

(compression release failure) may require replacement. Valve clearance not within the listed

specifications will require resetting the rocker arms to obtain the proper clearance.

7. If the engine turns over freely, the electric starter should be replaced or disassembled and checked.

See "Service" in this chapter. 120 volt starters labeled UL Listed/CSA Approved can be serviced;

however, starters labeled CSA must only be replaced. If the preceding steps fail to correct the problem,

the engine will require to be disassembled 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 voltage

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. A SCR (Silicon Controlled Rectifier) is located

in the circuit which requires a minimum turn on

voltage to allow it to conduct. Without the battery in

(+) POSITIVE LEAD

the circuit this turn on voltage is not present. The

SCR senses this and there will be no D.C. output

from the regulator / rectifier.

Each charging system has its own testing procedure.

Test the charging system using the applicable

procedure found on the following pages.

(-) ENGINE GROUND

350 Milliamp Charging System

CHECKING THE SYSTEM: The battery must be in

the circuit to perform the test properly. Set the

voltmeter to the 0 - 20 D.C. volt scale. Connect a

voltmeter across the battery. The voltmeter 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. 7).

MAGNETO GROUND

(GR)

BATTERY GROUND (BL)

BLACK

D.C. OUTPUT

LEAD (RED)

ELECTRIC STARTER

LEAD (ORG)

RED

18 Watt A.C. Lighting Alternator

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.

8).

ENGINE

With the engine running, minimum A.C. voltage across

the bulb should be:

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

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

defective. See Chapter 9 for "Disassembly

Procedure".

3 AMP

Before making any exterior tests, check for inoperative

switch, shorted wires and burned out headlight and/

or stop tail light. To check out the alternator, check

the A.C. lead to ground at each yellow wire (diag. 9).

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.

It 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 defective. See Chapter 9 for

"Disassembly Procedure".

A.C.

#4414 BULB

YELLOW

GREEN IGNITION STOP

NOTE: ON OLDER POINT IGNITION SYSTEMS,

THE A.C. OUTPUT LEADS ARE BLACK AND RED.

2.5 Amp D.C., 35 Watt Lighting

To check this system follow the meter hook ups at the

right, checking the D.C. neg and D.C. positive 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.

D.C. valve (+) 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 Volts 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.

A.C.

TWO DIODES

RED

D.C.

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

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

D.C.

3 AMP DC ALTERNATOR SYSTEM -

DIODE IN HARNESS SLEEVE

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

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.

11).

RED

DIODE

GREEN

With the engine running minimum values should read:

2500 R.P.M. - 8.0 Volts D.C.

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 one of these minimum readings are noted, the

system is okay. Check for bad battery, ammeter, wiring,

etc.

If no reading or less than the above reading, proceed

to make an A.C. output check by pulling back the

protective coating from the wire on the alternator side

of the diode. Test the A.C. voltage before the diode

using an A.C. voltmeter.

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 experienced, replace the

alternator. If the alternator puts out the minimum A.C.

voltage, replace the diode.

To 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. 12).

D.C.

SPADE CONNECTOR

SOLDERLESS CONNECTOR

FUSE HOLDER

IF BULB DOES NOT LIGHT OR LIGHTS WHEN POLARITY REVERSED, DISCARD DIODE.

NOTE: DO NOT USE ACID CORE SOLDER. BE

CAREFUL NOT TO APPLY HEAT DIRECTLY TO THE

DIODE - USE A HEAT SINK.

New heat shrink tubing can be installed by slipping

over the wires and heating with a hot air gun. If this is

not available, tape the diode and connections with

electrical tape.

5 AMP D.C. ALTERNATOR SYSTEM

REGULATOR-RECTIFIER 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 removed, and

the regulator-rectifier must be brought outside of the

blower housing. Reinstall 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. 14).

CAUTION: AT NO TIME SHOULD THE

ENGINE BE STARTED WITH THE BLOWER

HOUSING REMOVED.

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.

INSERT PROBES INTO CONNECTOR SLOTS. DO NOT REMO VE CONNECTOR WIRES.

YELLOW

RED

NOTE: D.C. OUTPUT MUST BE DISCONNECTED T O PERFORM A.C. OUTPUT TEST.

A.C. VOLTMETER

CAUTION: BLOWER HOUSING MUST BE INST ALLED WHEN RUNNING ENGINE

3600 R.P.M. - 28.0 Volts A.C.

If the minimum values are noted, the alternator is ok

and the regulator-rectifier is defective. If less than

above readings, the alternator is defective. See

Chapter 9 for "Disassembly Procedure".

3 Amp D.C. 5 Amp A.C. Alternator

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.

A wire harness( part # 36588) may be added to the 3

Amp D.C. / 5 Amp A.C. charging system to power an

electric clutch without the use of a battery. Test the

charging system using the applicable " Checking the

System " procedure listed in this section. Test the

diode in the harness by using a continuity test (diag.

15) Continuity should exist in one direction only.

Replace the diode if continuity exists after reversing

tester leads or no continuity is found. Use the

procedure for diode replacement found in the 3 AMP

alternator test (diag. 12).

RED LEAD

BLACK LEAD

DIODE

3 AMP D.C.

5 AMP A.C.

CHECKING THE SYSTEM: To check the system,

disconnect the plug and measure the D.C. voltage at

the red wire terminal (diag. 16). Measure the A.C.

voltage at the yellow wire terminal. With the engine

running, the minimum values should be:

MODELS OVM/OVXL/OHV12.5

3 Amp D.C. (Red wire)

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. (Yellow wire)

2500 R.P.M. - 8.5 Volts A.C.

3000 R.P.M. - 11.0 Volts A.C.

3600 R.P.M. - 13.0 Volts A.C.

MODELS OHV 13.5 - 17.0 (3/5 amp split)

3 Amp D. C. (Red wire)

2500 R.P.M. - 6.5 Volts D. C.

3000 R.P.M. - 9.0 Volts D. C.

3600 R. P.M. - 11.0 Volts D. C.

5 Amp A.C. (Yellow wire)

2500 R.P.M. - 15.0 Volts A.C.

3000 R.P.M. - 18.0 Volts A.C.

3600 R.P.M. - 22.0 Volts A.C.

If the above minimum values are noted, the system is

okay. Check for defective 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, check the voltage going into the diode from

alternator, at the lead on the alternator side of the

diode (diag.17). If low or no voltage is experienced,

replace the alternator.

D.C.

A.C.

RED

DIODE

YELLOW

DIODE

RED

YELLOW

Models OVM/OVXL/OHV12.5

(Red between Engine and Diode)

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.

DIODE

A.C.

Models OHV 13.5 - 17

(Read between Engine and Diode)

2500 R.P.M. - 17.0 Volts A.C.

3000 R.P.M. - 21.0 Volts A.C.

3600 R.P.M. - 24.5 Volts A.C.

If low or no voltage is experienced, replace the

alternator. If the alternator puts out the minimum A.C.

voltage, replace the diode.

7 Amp D.C. Alternator System Regulator-

Rectifier Under Engine Housing

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. 20).

A.C.

RED

DIODE

YELLOW

MAGNETO GROUND - GREEN

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 removed, 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. 21)

CAUTION: AT 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 is defective.

D.C. OUTPUT LEAD-RED

CAUTION: BLO WER HOUSING MUST BE INST ALLED WHEN RUNNING ENGINE

INSERT PROBES INT O CONNECTOR SLOTS DO NOT REMO VE CONNECTOR WIRES

YELLOW

RED

A.C. VOLTMETER

10 Amp A.C. Alternator

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. 22).

A.C. OUTPUT YELLOW

A.C.

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".

16 Amp Alternator System with External Regulator

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.

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.

With the engine running, minimum values should read:

D.C . OUTPUT - RED

2500 R.P.M. - 21 Volts A.C.

3000 R.P.M. - 26.5 Volts A.C.

3600 R.P.M. - 31.0 Volts A.C.

If the minimum values are noted, the alternator is

operating properly. If less than the above values are

noted, the alternator is defective.

VOLTAGE REGULATORS

If a known good or load tested battery fails to maintain

FUSE

SOLENOID

GREEN

MAGNET O GROUND

BATTERY

LIGHT

SWITCH

a charge, the charging system and the regulator can

be checked using a voltmeter. Set the voltmeter on

AMMETER

the 0-20 Volt D.C. scale and connect the probes

across the battery terminals. Note the battery voltage.

Start 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.

REGULATED D.C . OUTPUT

YELLOW

If the battery voltage exceeds 15 Volts D.C., or the

proper minimum A.C. voltage is noted during the

check, replace the regulator (diag. 23).

NOTE: D.C. OUTPUT MUST BE DISCONNECTED T O PERFORM A.C. OUTPUT TEST.

RED

FUEL SHUT-DOWN SOLENOIDS

If the engine is running, the solenoid can be checked

by removing the electrical plug-in at the base of the

solenoid. Almost immediately the engine should shut

down, if not replace the solenoid.

Test the solenoid off the carburetor by applying 12

volt D.C. from the battery positive terminal to the (or

one) solenoid terminal. Connect a jumper wire from

the metal housing (or other terminal) to a negative

battery terminal. The plunger should retract the full

travel distance. Disconnect the negative jumper lead

and the plunger should return to the extended position.

Replace if necessary (diag. 24).

SINGLE

DOUBLE

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. Remove

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 over using the

electric or recoil starter. A bright blue 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 spark occurs now, replace the LOS switch. If no

spark is seen, replace the ignition module.

FLOA T SWITCH

If equipped, the indicator light will flash if the oil level is at or below the add mark and the engine is turned over while attempting to start. Test by turning the engine over with the oil level below the add mark. If the indicator light does not flash, replace the indicator light.

INDICA T OR LIGHT

LIGHTED ENGINE ON/OFF ROCKER SWITCH

W/LOW OIL SHUTDOWN

TERMINALS (3)

ENGINE ON/OFF ROCKER SWITCH

TERMINALS (2)

SPACER

LOW OIL PRESSURE SENSOR

Test the sensor on a running engine using an

ohmmeter or continuity tester with one tester lead

connected the sensor terminal (with lead wire

removed) and the other to an engine ground. An open

circuit should be found with the engine running and

continuity should exist when the engine is shut off. If

continuity is found or the tractor oil pressure indicator

light is on or comes on at low engine RPM's, remove

the sensor and check engine oil pressure with a

master oil pressure gauge. The oil pressure of a

running engine should be above 10 p.s.i. (.700 bar).

If lower than 10 p.s.i. (.700 bar), an internal engine

problem exists (diag. 29).

LOW OIL SENSOR

This sensor must use a # 194 bulb in series with the

sensor for proper operation and to prevent sensor

damage. Remove the sensor from the engine and

attach the electrical plug. Attach a jumper lead from

an engine ground to the threaded portion of the

sensor. Place the keyswitch in the run position. The

indicator light should come on with the tip of the sensor

in air and go off when oil covers the sensor tip. The

response time of the sensor is between 5 and 15

seconds with 13 volts D.C. at the battery. Lower

battery voltage will result in a longer response time.

Use teflon-type pipe sealant on the sensor threads to

prevent oil leakage when reinstalling (diag. 30).

ELECTRIC STARTER SERVICE

This section covers the service procedures for the 12 and 120 volt electric starters. For diagnosis of the

starting circuit see Electrical Starter Troubleshooting in this chapter. Illustrations may not be identical in

configuration to the starter being serviced, but procedures and tests apply unless otherwise stated. Starters

labeled UL listed/ CSA approved are serviceable. Starters labeled CSA cannot be serviced, only replaced. If a

starter is serviced, the "O" rings on each end of the housing must be replaced.

12 VOLT or 120 VOLT ELECTRIC STARTERS

1. Remove the plastic dust cover on the bendix

end (diag. 31).

2. Push down the spring retainer and remove

the retainer ring.

3. Slide off the spring retainer, anti-drift spring,

gear, and drive nut.

4. If internal service is necessary (non-CSA)

starters only, 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 terminal

insulator slides out of the commutator cap

(some models).

7. Remove the armature.

BRUSHES

GASKET

ARMATURE

THRUST WASHER

RETAINER & SPRING

8. Inspect and replace as necessary, see the

section "Inspection and Repair" later in this

chapter. Use the reverse procedure for

assembly. ( For ease of assembly, place the

armature into the brush end of the frame first.)

RETAINING RING

DUST COVER

BENDIX ASSEMBL Y

Inspection And Repair

1. The pinion gear parts should be checked for

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 parts as necessary.

2. The brushes and brush card holder should be

checked for wear. With the armature in place

and the brushes engaging the commutator

surface, check 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. 32

& 33).

4. The armature should be checked for glazing or

wear. If necessary the armature can be turned

down in a lathe. While rotating, polish the

commutator bars using a piece of 00 sandpaper

(diag. 34). Light pressure and back and forth

movement should be used. Recut the

commutator 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. 35).

FIELD COIL CONNECTORS

BRUSH SPRINGS

12 VOL T

FIELD COIL CONNECTORS

CONNECTION POINT OF POWER CORD LEADS

120 VOL T

34 35

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 grip 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 mark 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. Insert 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 terminal post using electrical tape or

heat shrink tubing. Route the wires to prevent damage during assembly.

8. Install the armature 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, but do not overtighten.

9. Install the thrust washer on the end of the armature and the 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

GENERAL INFORMATION

Tecumsehs brake systems are required to meet compliance standards which has become a federal law as of

June 30, 1982. Listed below are two methods used by original equipment manufacturers to meet compliance

standards.

1. Use of the blade brake clutch in conjunction with a top mounted recoil starter or 12 volt electric starter.

The blade must stop 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 with the rope handle on the engine as opposed to within 24 inches (61 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 blade

must stop 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 killing the engine and stopping the lawnmower

blade within three seconds after the operator releases the engine/blade control bail at the handle of the lawnmower.

This system is available on 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

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 out (diag. 1).

In order to restart the engine, the engine/blade control bail must be applied. This action pulls the brake pad away

from the inside edge of the flywheel and opens the circuit to the ignition ground out terminal. On electric start

systems the starter is energized by an ignition/start switch or a two motion control. On nonelectric start systems,

the recoil starter rope must be pulled to start the engine (diag. 2).

GROUND

CLIP

IGNITION

GROUND

WIRE

GROUND

CLIP

IGNITION

GROUND

WIRE

BRAKE "ON"

BRAKE

PAD

BRAKE "OFF"

COMPONENTS

The brake bracket assembly consists of a replaceable

brake lever and pad, an ignition kill switch, and a tension

spring (diag. 3). Late production brake brackets are

serviced as a complete assembly.

The ignition ground terminal is a plastic block with

a wire extending out of it. The wire is connected to the

ignition ground out spade on the solid state module.

The brake lever contacts the wire of the ignition ground

terminal when the engine/blade control bail is released,

and the ignition module is grounded. This stops the

solid state module from firing the spark plug (diag. 3).

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 electric 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 bail is depressed.

GROUNDING

CLIP POSITION

TOP VIEW

BRAKE PAD

LINKAGE

Where a two motion control is used the interlock switch

is utilized as the starter switch.

The brake spring supplies the pressure to the brake

lever and brake pad to stop the flywheel.

MOUNTING HOLES

MECHANISM FULL DOWN BEFORE SCREWS TORQUED

The control cable transfers the motion of the engine/

blade control bail to the brake system.

SERVICE

Service on part or all of the flywheel brake assembly will require a partial disassembly of the engine to allow the

flywheel and brake bracket to be removed.

Remove the necessary components using steps 1-8 as outlined in Chapter 9 under "Disassembly".

ELECTRIC START INTERLOCK SWITCH

BRAKE BRACKET ASSEMBLY

Late production brake brackets are serviceable only by installing a complete brake bracket assembly.

On serviceable brake brackets, continue by removing 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) thickness 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 lever 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 terminal grounding wire for proper alignment

and contact with the brake arm. Insure that all electrical

connections are clean and secure (diag. 5).

STARTER INTERLOCK SWITCH

The engine/blade control must close the interlock switch

before the starter can be engaged. To check the

interlock switch, use an ohmmeter or continuity light

to perform a continuity check. Disconnect the wires off

the switch before performing a continuity check.

Continuity should exist between the two terminals when

the interlock switch button is completely depressed.

No continuity should exist when the button is released.

If the switch fails replace the switch (diag. 6).

To replace the interlock switch, 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 bracket. Use the self-tapping screws supplied

with the new switch to make threads in the bracket.

Install the interlock switch onto the brake bracket in

the proper position and secure the switch to the brake

bracket with the machine screws supplied. Be careful

not to overtighten the screws as switch breakage can

occur (diag. 6).

GROUNDING

CLIP POSITION

TOP VIEW

BRAKE PAD

MOUNTING HOLES

MECHANISM FULL DOWN BEFORE SCREWS TORQUED

ELECTRIC START INTERLOCK SWITCH

LINKAGE

CONTROL CABLE

If replacing the cable conduit screw with a screw other

than a service part replacement, be certain 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. 7).

BRAKE BRACKET REPLACEMENT

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.

8).

When completed, check for less than 3 second stop

time.

SCREW END MUST NOT BLOCK LEVER ACTION

MOUNTING HOLES

MECHANISM FULL DOWN BEFORE SCREWS TORQUED

CABLE CLAMP SCREW

CHAPTER 8 IGNITION

GENERAL INFORMATION

Overhead valve four cycle Tecumseh engines use solid state capacitor discharge modules to provide high

voltage to fire the spark plug. This is an all electronic ignition system with all the components located outside

the flywheel. The modules look similar but are not interchangeable. If necessary, the correct replacement

module should be found using the Master Technician's Parts Manual.

The solid state ignition system consists of flywheel magnets and a flywheel key, charge coil, capacitor, a silicon

controlled rectifier, pulse transformer, trigger coil, high tension lead, and a spark plug. Everything except the

flywheel magnets, key and the spark plug are located in a encapsulated ignition module. This solid state (CDI)

module is protected by epoxy filler from exposure to dirt and moisture. This system requires no maintenance

other than checks of the high tension lead and spark plug.

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 volts)

until it is released by an electrical switch (SCR). As

the magnet continues to rotate, it passes 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 to

25,000 volts. This voltage follows along the high

tension lead to the spark plug where it arcs across

the electrodes and ignites the air-fuel mixture (diag.

1).

COMPONENTS

The solid state module is a complete unit that

includes the laminations and spark plug wire.

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 module

arcs the air gap which causes a spark and ignites the

air-fuel mixture in the cylinder (diag.2).

NOTE: Always consult parts manual for correct plug

and reach.

STANDARD PLUG

OHV

The flywheel with magnets provide the magnetic flux

(or field) which is necessary to induce voltage and

trigger the module to provide spark.

The flywheel key locates the flywheel to the

crankshaft in the proper position for ignition timing. If

a flywheel key is sheared, or partially sheared, the

engine will not start or can be difficult to start (diag.

3).

NOTE: Always replace flywheel keys by Model and

Specification Number. Tecumseh has some keys that

look similar but affect ignition timing.

TESTING PROCEDURE

1. Check for spark using a commercially available

spark tester and following the tester's

recommended procedure.

2. Check the spark plug for cracks in the porcelain,

pitted or burned electrodes, excessive carbon

buildup, and proper .030" (.762 mm) air gap

setting. Replace if questionable. Try to start and

run the engine. If the engine will not start or run

properly proceed to step #3.

3/4" (19.05 mm)

3. Attach the spark plug wire to the spark plug

tester and ground the tester as in step #1.

Remove the blower housing, disconnect the

MAGNETS

ignition grounding lead at the ignition module.

Reinstall the blower housing and crank the

engine over. If spark occurs, check the ignition

switch, safety interlock switches, or electrical

wiring for shorting to ground.

4. Check the air gap between the flywheel magnets and the laminations of the ignition module. It should be

.0125" (.3175 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, move 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.

4).

6. Examine the ignition module and lamination assembly for cracks in insulation or other damage, which

would cause shorts or leakage of current.

7. Check the operation of the ignition module using an approved tester following the instructions furnished

with the test unit, or booklets offered by the Tecumseh Products Co. Engine and Transmission Group

Service Division.

Ignition modules are permanently attached to the lamination and must be serviced as an assembly.

FOUR CYCLE IGNITION TROUBLESHOOTING

Spark

Check for the correct spark

plug

Check flywheel and key for

damage or sheared key

Set proper air gap on

ignition module

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 from

equipment and repeat

test

No Spark

Engine problem, check

for shorts or grounds in

wiring

Test ignition module

for intermittent or

weak spark

Check electric starter and

battery if applicable

Disconnect ignition

ground-out wire at

the igniton module &

repeat test

Check for proper air gap

on ignition module

and repeat test

Check flywheel magnets

for strength

Test ignition module

SERVICE

To remove the ignition module or the flywheel from

the engine, see Chapter 9 under "Disassembly".

GAP GAUGE

(670256)

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. 5).

Replace the plug if the points on the base of the plug

are pitted or burned, or if the porcelain is cracked

anywhere.

When reinstalling the plug make sure it is clean of all foreign material.

NOTE: DO NOT USE A SAND BLASTER TO CLEAN PLUGS, MICROSCOPIC PARTICLES LEFT IN THE

PLUG CAN SCORE THE ENGINE CYLINDER DURING OPERATION. USE A SOLVENT AND A WIRE BRUSH

TO CLEAN, AND USING EYE PROTECTION, BLOW OUT THOROUGHLY WITH COMPRESSED AIR.

When replacing a spark plug consult the parts breakdown for the correct spark plug to be used in the engine

being serviced.

Install the spark plug in the engine and tighten it to 180 inch pounds (20.5 Nm) torque. If a torque wrench is not

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 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 FREQUENT SPARK PLUG FOULING

1. Carburetor setting is too rich or the air cleaner

is restricted.

2. Partially closed choke shutter.

3. Poor grade of gasoline.

4. Improper fuel.

5. Restricted exhaust system.

6. Incorrect spark plug.

7. Incorrect spark plug gap.

8. Oil level is too high, or the breather is restricted.

9. Faulty piston rings.

10. Weak ignition system.

Normal

Worn

Carbon Deposit

Oil Deposit

IGNITION TIMING CHECK

In order for an engine to run effectively 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 known as Before

Top Dead Center (BTDC). If the mixture is ignited too

soon, kickback can be experienced due to preignition.

If the mixture is ignited too late, loss of power can be

experienced due to retarded spark. A partially sheared

or the wrong flywheel key can cause kickback, loss

of power, or an inability to start the engine with a good

spark. Check the flywheel key if one of these

symptoms exist. See Chapter 9 under "Service" for

the disassembly procedure.

Timing on a solid state module is not adjustable. The

air gap check consists of having the proper .0125"

(.3175 mm) air gap gauge, part # 670297 between

the flywheel magnets and the laminations of the

module while tightening the mounting screws to the

proper torque. 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

air gap check is completed (diag. 7).

.0125" (.3175 mm)

SERVICE TIPS

DO NOT:

Interchange flywheels, flywheel keys, or spark plugs.

Use flywheels with cooling fins that are broken off.

Use a standard business card as an air gap gauge.

Attempt to reglue the spark plug lead back into a solid state module.

Store a solid state module within 20 feet (6.1 meters) of an unshielded welder.

CHAPTER 9 INTERNAL ENGINE AND CYLINDER

GENERAL INFORMATION

This chapter covers the cylinder block, piston and rod assemblies, cylinder head, crankshaft, camshaft, valve train, breather, cylinder cover, flywheel, counterbalance systems, and lubrication systems. The governors and the governor systems are covered in Chapter 4.

All Tecumseh engines covered in this manual are four cycle engines with the valves in the engine head. 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.

OPERATION

4-CYCLE ENGINE THEORY

All 4-cycle engines require four piston strokes or cycles to complete one power cycle. The flywheel or the equipment load on the crankshaft provides the inertia to keep the engine running smoothly between power strokes.

The engine camshaft gear is twice as large as the mating gear on the crankshaft to allow proper engine valve timing for each cycle. The crankshaft makes two revolutions 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 valve closes. The piston then rises, compressing the air-fuel mixture trapped in the combustion chamber due to both valves being closed (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 power 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).

After the piston reaches Top Dead Center (TDC), the four cycle process will begin again as the piston moves downward and the intake valve opens.

LUBRICATION SYSTEMS

The lubrication system used with all Tecumseh horizontal crankshaft engines covered in this manual utilize a splash type system. An oil dipper on the connecting rod splashes oil in the crankcase to lubricate all internal moving parts. The oil dipper is either bolted on or may be cast on to the cap with one of the rod bolts (diag. 6).

All vertical shaft engines use a positive displacement plunger oil pump or a rotary 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. 7). A crankshaft drilling also provides oil to the crankpin journal on engine models OHV 13.5 -16.5.

On all Tecumseh vertical shaft 4-cycle engines, the oil is sprayed out under pressure through a small hole between the top camshaft and crankshaft bearing to lubricate the piston, connecting rod, and other internal parts (diag. 5).

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 flange (diag. 8).

CRANKCASE PASSAGE

PLUG

CAMSHAFT

DRILLED CAMSHAFT PASSAGE

DIPPER

SPRAY MIST HOLE

MAIN BEARING OIL GROOVE

CRANKSHAFT OIL PASSAGE

BARREL TYPE LUBRICATION PUMP

ASSEMBLE PUMP HOUSING WITH INSIDE CHAMFER TOWARD CAMSHAFT GEAR

The rotary pump is driven by the camshaft. It uses a lobed gear in a rotating ring to provide positive oil displacement (diag. 9).

SPRAY MIST HOLE

OIL DRAIN HOLE

COUNTERBALANCE SYSTEMS

Some Tecumseh engines may be equipped with an Ultra-Balance® counterbalance system. This system uses a single weighted shaft that is driven off the crankshaft. This shaft's function is to counteract the imbalance caused by the counterweights on the crankshaft (diag. 10).

FLAT

NOTE: INSTALL OIL PUMP AFTER THE SUMP IS ON

DRIVE GEAR

COUNTERBALANCE SHAFT

A dual shaft counterbalance is also used on some engine models. A gear on the crankshaft drives the counterbalance with the thicker gear, which in turn drives the second counter balance shaft. For timing of either counterbalance system, see " Engine Assembly Procedure " in the Service section of this chapter.

CAMSHAFT

GOVERNOR

FLANGE

COMPONENTS

The cylinder block houses the piston, crankshaft, and along with the cylinder cover all the internal components. The block is a one piece diecast aluminum alloy cylinder casting which may have a cast iron liner (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 casting that is bolted to the top of the cylinder block. The

overhead design contains all of the valve train except for the camshaft, lifters, and push rods. The crankshaft converts the up and down piston movement to the rotational force (torque) by an offset crankpin

or rod journal. The camshaft lobes push 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 valve lifter

and cam lobe contact. The valve retainers lock the spring to the valve stem. The valve lifters maintain contact on the camshaft, move the push rods to pivot the rocker arms and move

the valves. 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 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 or aluminum housing that rides an

offset on the camshaft. The rotary pump consists of a lobed gear in a rotating ring that is driven by the camshaft. The flywheel provides the mass to smooth the effects of one power stroke every other crankshaft revolution.

Flywheels are made of aluminum alloy or cast iron. The flywheel fins act as a fan to cool the engine.

CHAMPFER UP TOWARD CAM

PUSH ROD GUIDE PLATE

PUSHRODS

LIFTERS

RING

SHAFT

ROTOR

OIL SEAL REMOVED

ROTARY PUMP

SNAP RING

CAMSHAFT

CRANKSHAFT

VALVES

CRANKCASE BREATHER

FLYWHEEL

ENGINE OPERATION PROBLEMS

ENGINE KNOCKS

Associated equipment loose or

improperly adjusted

Check for e xcessive carbon in

combustion chamber

Loose flywheel examine key, key way

and proper flywheel nut torque

Ignition timing or

incorrect spark plug

Loose or worn connecting rod

Worn cylinder

OVERHEATS

Low oil level or wrong viscosity oil

Cooling air flow obstructed or clogged

cooling fins

Carburetor improperly adjusted or

improper RPM setting*

Ignition timing or

incorrect spark plug

Carbon in the combustion chamber

SURGES OR RUNS UNEVENLY

Fuel cap vent obstructedExcessive engine loading

Dirty carburetor or air filter

Carburetor improperly adjusted

Governor sticking, binding or improper

RPM setting

Carburetor linkage, shafts or shutters

sticking or binding

Intermittent spark, check ignition or

incorrect spark plug

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

Damaged gaskets, seals or "O" rings

Lean carb setting causing overheating

(adjustable carb)

Piston rings worn

Worn or glazed cylinder

Valve guides worn excessiv ely

ENGINE OPERATION PROBLEMS

ENGINE MISFIRES

Carburetor improperly adjusted

Wrong or fouled spark plug

Valves stic king or not seating properly

Ignition timing or

incorrect spark plug

Excessive carbon build up

Improper Valv e Lash

Weak valve spring

ENGINE VIBRA TES EXCESSIVEL Y

Bent crankshaft

Attached equipment out of balance

Loose mounting bolts

If applicable counter balance not

properly aligned

BREA THER 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 or lubrication or improper

lubrication

Carburetor improperly adjusted

Exhaust Obstructed

Improper valve lash

Loss of compression (worn rings,

blown head gasket)

TESTING

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.

4. Remove the cylinder head and check for excessive carbon in the combustion chamber. Also check that

the head gasket fit is correct, and the spark plug for proper reach and heat range (correct spark plug for the engine).

5. Check for the proper valve lash using a feeler gauge.

6. Check the internal components (piston, cylinder, connecting rod, crankshaft journal) for excessive

clearance. See Chapter 10 under "Specifications".

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 "Service."

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 necessary.

6. Check the ignition timing. See Chapter 8 "Ignition - Service."

7. Remove the cylinder head to check for excessive carbon buildup or a leaking head gasket. Clean or

replace as necessary.

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 necessary.

5. Visually check all linkages. Check the governor shaft, throttle shaft, or pivot points for binding.

6. Check the ignition module operation using a gap type tester installed between the high tension lead

and spark plug. Check for intermittent spark.

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. Check valve lash. Inspect the valves and valve seats for leakage. Check for scoring or discoloration on

the valve stem in the valve guide area. Recut the valves and seats if questionable. See "Valve Service" in this chapter.

ENGINE VIBRATES EXCESSIVELY

1. Remove the spark plug wire. 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. Significant 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 for excessive 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.

2 and 4-CYCLE RPM SETTINGS 30

NOTE: MICROFICHE CARD 30 RPM'S ARE NOT ON

PAPER NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS.

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.

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 necessary. The computer parts lookup systems also have RPM information listed in each individual engine parts list.

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 proper level.

3. Readjust the carburetor or remove the carburetor for cleaning. See Chapter 3 under "Service."

4. Check the exhaust port or muffler for a restriction preventing proper exhaust flow.

5. Check the engine valve lash. Reset the valves at the proper lash.

6. Check the valves for proper seating and valve guide clearance. Recondition the valves and seats.

Replace the valves if necessary. See "Cylinder Head and Valve Train Service" in this chapter.

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, screws, or some models require taps upward with a soft face hammer loosening the plastic tank wedges in the blower housing slots.

5. Remove the blower housing by first unscrewing the screw holding the dipstick tube to the blower housing and removing the remaining bolts holding on the blower housing.

6. Unplug the ignition kill wire from the terminal on top of the ignition module and unbolt the ignition module.

7. Locate the piston at Top Dead Center (TDC) on the compression stroke for easier valve train service.

FLYWHEEL TOOL

METAL HAMMER

SOCKET WRENCH

FLYWHEEL

KNOCK OFF TOOL

8. Relieve the compliance brake pressure on the flywheel if applicable. Compress the spring by moving the lever toward the spark plug end and when the hole in the lever aligns with the hole in the bracket secure the lever in this position with alignment tool part # 670298.

9. Remove the flywheel nut, washer, and starter cup. Use a part # 670305 strap wrench to hold the flywheel from turning (diag. 12). Thread the appropriate flywheel knock-off tool (7/16" / 11.112 mm use part # 670103, 1/2" / 12.7 mm use part # 670169, 5/8" / 15.875 mm use part # 670314, 11/16" / 17.462 mm use part # 670329) on the crankshaft until it bottoms out, then unthread it one complete turn. Lift upward under the flywheel using a large screwdriver while avoiding contact with the alternator coils or magnets, 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 flywheels with cored holes (diag. 14).

NOTE: DO NOT USE A JAW TYPE PULLER.

SCREWDRIVER TO RAISE FLYWHEEL

10. Remove the flywheel key and alternator if equipped, and baffle plate.

11. Remove the muffler.

12. Remove the intake pipe, spacer if equipped, 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.

13. Remove the head by first removing the valve cover. The push rod guide plate must be removed to access one of the head bolts. Remove the rocker arms by loosening the two locking nuts or allen head screws. Use a 3/16" Allen wrench and a 7/16" wrench on OHH, OVRM and OHV 11-13 use a 1/2 wrench, OHV13.5 - 17 use a 3/16" allen and 1/2" wrench. Remove the rocker arm nuts or rocker arm bearings followed by the rocker arms, rocker arm studs, guide plate, and push rods. Remove the head bolts, head, and head gasket.

NOTE: ON SOME OHV ENGINES THE EXHAUST PUSH ROD CAN ONLY BE REMOVED AFTER THE HEAD IS OFF. YOU MUST HAVE IT BACK IN BEFORE REASSEMBLY.

On engine models OHM, OHSK120, OVM, OVXL and OHV, with independent cylinder head and rocker box, the valve springs, caps, retainers, and retainer screw must be removed to allow the rocker box to separate from the head. Remove the jam nut, adjusting nut, rocker arm bearings, rocker arms, push rods, guide plate, and the rocker arm retainer screw.

Next to prevent valve or piston damage turn the piston down in the cylinder. Then place a 3/4" (19.05 mm) deep socket over the valve cap and strike the top with a steel hammer (diag. 15). This action loosens the cap. Remove the cap, retainers, and valve springs. Remove the rocker arm housing, head bolts, head, head gasket and valves. Notice the "O"rings used to seal the rocker box , valve stems, and push rod tubes.

14. Remove the crankcase breather if necessary.

15. Remove the cylinder cover or mounting flange

using a seal protector positioned on the seal to prevent seal damage. The crankshaft must be free of rust or scale to slide the cover or flange off the crankshaft. OHH engines with a ball bearing on the P.T.O. end of the crankshaft require the oil seal and the snap ring to be removed prior to the cylinder cover removal. For 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 flange (diag. 16, 17, 18, 19).

16. On engines equipped with 8-1/2 :1 gear

reduction, remove the auxiliary shaft from the cover by removing the retaining ring and sliding the shaft out of the washers and drive gear.

17. Align the timing marks on the camshaft and

crankshaft gears and remove the internal components (diag. 20).

18. Remove the lifters, rod cap, and counterbalance

shaft or gears if applicable.

19. 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.

20. Remove the valves from the head on models

OHH and OVRM by supporting the valves with fingers while compressing the valve springs, one at a time, with thumbs. Slide the large opening in the retainer toward the valve stem to remove (diag. 21). On all other overhead valve engine models, place a 3/4" (19.05 mm) deep socket over the valve cap and strike the top with a steel hammer. This action loosens the cap. Remove the cap, retainers, and valve springs. The valve springs must be assembled on the same valve they are removed from (diag. 15).

WORM GEAR

SNAP RING

OIL SLEEVE TOOL

MOUNTING FLANGE

OIL SEAL

GEAR

OIL SEAL REMOVED

BEVELED TOOTH

CRANKSHAFT GEAR

CAMSHAFT GEAR

TIMING MARK

CYLINDERS

Visually check the cylinder for broken or cracked fins or a scored cylinder bore. Check the main bearing for wear or scoring. If the main bearing is worn or scored it can be replaced on some models. See "Crankshaft Bearing Service" in this chapter.

Use a dial bore gauge or transfer gauge with a micrometer to accurately measure the cylinder bore. Measure in the piston travel area approximately 1/2" to 3/4" (12.7-19.05 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-sized to .010" or .020" (.254-.508 mm) oversize. In some cases engines are built with oversize cylinders. If the cylinder is oversize, the oversize value will be imprinted in the top of the cylinder (diag. 22).

To recondition 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. Tecumseh recommends 380 grit for finish in a standard cross hatch.

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.

.010

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. Move the hone up and down at a rate of 50 strokes per minute to avoid putting ridges in the cylinder wall. Every fourth or fifth stroke, move the hone far enough to extend the stones one inch beyond the top and bottom of the cylinder bore.

Check the bore diameter every twenty or thirty strokes for size and a 350 - 450 crosshatch pattern. If the stones collect metal, clean the stones with a wire brush when the hone is removed.

If cylinder oversizing is needed we recommend boring the cylinder. This service is offered by many Service Dealers. You also may wish to contact a local machine shop.

Clean the cylinder and crankcase with warm, soapy water, rinse with clean water, and dry thoroughly. Continue the cleaning procedure until a clean white cloth wiped on any internal surface reveals no honing residue or dirt.

Replace the piston and the piston rings with the correct oversize parts as indicated in the parts manual.

CYLINDER HEAD AND VALVE TRAIN SERVICE

Check the cylinder head for warpage by placing the head on a precision flat surface. If warped in excess of .005" (.127mm), 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 surface 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 gasket and torque the head bolts in 60 inch pound (6.7 Nm) increments in the numbered sequence torques in specification section (diag. 23 & 24).

Valves, Springs, And Push Rods

The valves should be checked for proper lash, sealing, and wear. Valve condition is critical for proper engine performance. Valve lash should be checked before removal of the engine head if any of the following conditions are experienced; a popping is heard through the intake or exhaust, an engine kickback is experienced, or when excessive valve train noise is heard.

Valve lash (between the rocker arm and valve stem) 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). See specification section.

When servicing the valves, all carbon should be removed from the valve head and stem. If the valves have been checked and are in a usable condition, the valve face should be ground 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 (.794 mm), the valve should be replaced (diag. 25).

1/32" (.794 mm)

TORQUE SEQUENCE

OVRM / OHH, OHSK50 - 70

TORQUE SEQUENCE

OHV 11 - 17, OHM, OHSK80 - 130

MARGIN

FACE

MINIMUM DIMENSION

STEM

Valves are not identical. Valves marked "EX" or "X" are installed in the exhaust valve location. Valves marked "I" are installed in the intake valve location. If the valves are unmarked, the smaller valve (head) is installed in the exhaust valve location.

If the spring has dampening coils, the valve spring should be installed with the dampening coils away from the valve cap and retainers (diag. 26).

The valve springs should be checked for both ends being parallel and the free length being at least 1.105" (28.067 mm) for OHH and OVRM engines, 1.980" (50.292 mm for OHM, OVM, OHSK, OVXL, and OHV engines when the valves are removed for service. Replace the springs if necessary.

The push rods should be checked for straightness and the ends for wear. If the push rod ends are worn or damaged, inspect the corresponding rocker arm socket or valve lifter for wear. Replace if necessary.

FREE LENGTH

OVRM/OHH/

OHSK50-70

1.105" (28.067 mm)

ALL OTHERS 1.980" (50.292 mm)

DAMPENING COILS LOCATED CLOSER TOGETHER

THIS END MUST FACE TOWARD THE STATIONARY PART OF THE ENGINE

(CYLINDER HEAD)

PISTONS, RINGS, AND CONNECTING RODS

Piston

The piston should be checked for wear by measuring near 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 a 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 value imprinted on the top of the piston (diag. 27).

INDICATES .010" (.254 mm) OVERSIZE PISTON

PISTON MEASUREMENTS ARE TAKEN AT

BOTTOM OF SKIRT 900 FROM WRIST PIN HOLE

Piston Rings

After the cylinder bore diameter has been checked and is acceptable to rebuild, the ring end gap should be checked using new 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.

30). 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.

Use a ring expander to remove and replace the rings. Do not spread the rings too wide or breakage will result.

Piston Ring Orientation

If the top compression ring has an inside chamfer, this chamfer must face UP. The second compression ring will have either an inside chamfer or an outside notch. The rule to follow is an inside chamfer always faces up. An outside notch (diag. 31) will face down or towards the skirt of the piston.

CYLINDER

CHAMFER

PISTON

PISTON RING

1ST COMPRESSION RING

2ND COMPRESSION RING

3RD OIL CONTROL RING

EMISSION RINGS

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. 31).

NOTE: Always stagger the ring end gaps on reassembly.

1ST COMPRESSION RING

2ND COMPRESSION RING

3RD OIL CONTROL RING

CONNECTING RODS

Some engine models have offset piston pins (not centered) to centralize the combustion force on the piston. When installing the connecting rod to the piston it is imperative that the rod be installed correctly. On engine models OVM, OHM, OHSK120 - 130, and OVXL, the piston will have an arrow stamped on the top of the piston. On OHV 13.5 - 17 engines, an arrow is found on the piston skirt. The arrow on the top of piston or on the piston skirt must point toward the push rods or the carburetor side of the engine when installing it in the cylinder. (diag. 32) If the piston does not have an arrow, the piston can be installed either direction on the connecting rod. On all engine

models, the match marks on the connecting rod and cap must align and face out when installing the piston assembly into the engine (diag. 33 &

34).

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 (5.65 Nm) increments until the specified torque is achieved.

CRANKSHAFTS AND CAMSHAFTS

Inspect the crankshaft visually and with a micrometer for wear, scratching, scoring, or out of round condition at the bearing surfaces. Check for bends on the P.T.O. end using a straight edge, square or a dial indicator.

CAUTION: NEVER TRY TO STRAIGHTEN A BENT CRANKSHAFT.

The timing marks on the camshaft and the crankshaft gears must be aligned for proper valve timing. (diag. 35 & 36).

MATCH MARKS

CAMSHAFT GEAR TIMING MARK

ARROW DIRECTION

MATCH MARKS

3433

BEVEL

CHAMFER TOOTH

CRANKSHAFT GEAR

PUNCH MARK

SMALL HOBBING HOLE

CRANKSHAFT

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.

OHH and OHSK50 - 70 engines use serviceable MCR components and must be assembled as illustrated in "Assembly" with a thrust washer placed on the camshaft next to the compression release weight.

NOTE: Some OHH models used on chipper/ shredders may not require a compression release.

GEAR KEYWAY

CAMSHAFT GEAR

SMALL HOBBING HOLE

COMPRESSION RELEASE MECHANISM

Mechanical Compression Release (MCR) camshafts have a pin located in the camshaft, that extends above the intake or exhaust cam lobe, to lift the valve to 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).

Some OHH engines use a composite camshaft. This camshaft is used on OHH/OHSK 50-70 engines that have been manufactured after DOM (date of manufacture) 7048. This change that took place in February of 1997 and is basic on the OHH engines, except those units that use extended camshafts which will continue to use a cast iron camshaft. A camshaft kit replaces the old camshaft and includes compression release components and two light tension valve springs. It is CRITICAL that the new valve springs be installed or lobe damage will occur on the camshaft.

NOTE: You must install the thrust washer between the cover and cam to prevent wear.

Some OVRM engines use a ramp compression release (RCR) system that works with the intake valve. The ramp is located on the backside of the intake cam lobe. The ramp delays the intake valve closure, resulting in lower emissions and reduced compression for easier pull starting (diag. 39).

Valve Seats

COMPRESSION RELEASE

INTAKE

CAMSHAFT

COMPRESSION RELEASE SPRING

THRUST WASHER

INSERT SPRING END "A"

Valve seats are not replaceable. If they are burned, pitted, or distorted they can be regrounded using a grinding stone or a valve seat cutting tool. Valve seats are ground to an angle of 46 degrees to a width of

EXHAUST

3/64" (1.91 mm). The recommended procedure to properly cut a valve seat is to use the Neway Valve Cutting System, which

consists of three different cutters. OVRM and OHH 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 # 111. 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.

First, use the 60 degree cutter to clean and narrow the seat from the bottom to the center (diag. 40). Second, use the 31 degree cutter to clean and narrow the seat from the top toward the center (diag. 41). Third, use the 46 degree cutter to cut the seat to a width of 3/64" (1.191 mm) (diag. 42). Check the contact area

of a new or reconditioned valve face on a finished valve seat. Using fingers, snap the valve sharply against the corresponding valve seat and view the line imprinted on the valve face. The contact area or line should be continuous and appear on the upper 1/3 of the valve face. Re-cut the seat to move the contact area higher or lower if necessary and recheck the contact area.

BOTTOM NARROWING CUTTER

TOP NARROWING CUTTER

TOP NARROW

SEAT CUTTER

31 46

BOTTOM NARROWING

3/64" SEAT

BOTTOM NARROW

SEAT

VALVE LIFTERS

When removing the lifters, mark the lifters to install the lifter in the same position as it was removed from. The valve lifters may be slightly different lengths. Visually check the lifter for wear on the cam contact surface and push rod contact surface.

VALVE GUIDES

Engine models OVM, OHM, OHSK80 - 130, and OVXL have valve guides that can be reamed 1/32" (.794 mm) oversize or be replaced as service parts. All other overhead valve engines have valve guides that are permanently installed in the cylinder head. If the guides get worn excessively, they can be reamed oversize to accommodate a 1/32" (.794 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.

VALVE GUIDE REMOVAL (WHERE APPLICABLE, CONSULT PARTS MANUAL)

1. Submerge the head in a container of oil so that both guides are completely covered with oil.

2. Heat the oil on a hot plate approximately 1520 minutes until the oil begins to smoke. Oil temperature must be 375

- 400oF (1900 -

2040C).

GUIDES

HEAD

CAUTION : USE PROTECTION FOR EYES AND HANDS, BE CAREFUL ! THE HOT OIL

OIL

AND HEAD CAN EASILY CAUSE BURNS.

3. Using a pliers, remove the head from pan of

HOT PLATE

oil. Carefully drain the excess oil out of the head. Quickly work the next two steps while the head is hot to prevent pressing the guides out with the head too cool. Guides removed too cool will permanently damage the head

HEAT UNTIL OIL BEGINS TO SMOKE 43

by removing aluminum necessary to hold the new guides in place.

4. Place the head on the bed of an arbor press on parallels with the snap rings on the long ends of the guides facing down.

5. Using a 1/2" (12.7 mm) diameter, 6" (15.24 cm) drift punch located in the center of the old valve guide, push the guide out of the head with the arbor press. Do not allow the drift punch to contact the head during this step.

VALVE GUIDE INSTALLATION

1. Install the snap rings on the new replacement valve guides. Place the valve guides in a freezer for an hour or longer to ease assembly.

2. Submerge the head in a container of oil so that the valve guide bores are completely covered with oil. Heat the container on a hot plate approximately 15-20 minutes until the oil begins to smoke. Oil temperature must be 375o - 400oF (1900 - 2040C).

CAUTION : USE PROTECTION FOR EYES AND HANDS, BE CAREFUL ! THE HOT OIL AND

HEAD CAN EASILY CAUSE BURNS.

3. Using a pliers, remove the head from pan of oil. Carefully drain the excess oil out of the head. Quickly work the next two steps while the head is hot to prevent damage to the guides or the head.

4. Place the head on a 6" x 12" (15.24 x 30.5 cm) piece of wood with the head gasket surface down.

5. Insert the new guides in the head with the long end of the guides up. It may be necessary to use a rubber or rawhide mallet to fully seat the new guide to the snap ring.

NOTE: DO NOT USE A STEEL HAMMER TO SEAT THE NEW GUIDE, GUIDE OR HEAD DAMAGE

WILL RESULT.

6. Allow the head to cool and re-cut both valve seats using a Neway cutter to align the new guides to the valve seats.

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 down to allow return of oil back into the crankcase.

TUBE

Top Mounted Breather

This type of breather is mounted in the top and rear of the cylinder block in vertical shaft engines. The umbrella check valve allows positive pressure to be vented through the element and out the tube. Most engines have the breather tube connected to the air cleaner assembly (diag. 44).

Late production OVRM engines use the rubber boot and breather tube as a "pop 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. 45).

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.

OHH engines use an umbrella valve type breather that is found in the rocker arm cover. Use solvent and compressed air to clean the area if necessary. Individual components are serviced only by the replacement of the complete cover.

Side Mounted Breather

This type of breather mounts over the valve compartment and uses a reed style check valve. Clean the internal element or reed area with solvent and compressed air if necessary. When installing, the drain holes must be open and be on the bottom.

COVER

ELEMENT

BAFFLE

OIL RETURN

GASKET

BODY

REED

CHECK VALVE

PRESSURE OUT

BODY

On OHV13.5 - 17 engines, align the reed valve and plate parallel to the top surface of the breather opening in the crankcase. If the plate has a notched corner, install the notch toward the P.T.O. side of the engine. If the plate is marked, install the plate with the mark facing out. Hold the reed valve and plate in this position while tightening the screw.

1 - Valve, Reed 2 - Plate, Limit 3 - Screw 4 - Baffle/Gasket 5 - Cover

DRAIN HOLE

BREATHER OUTLET TO CARB

FILTER

UMBRELLA

GASKET

COVER

TUBE

4746

CYLINDER COVER, OIL SEAL, AND BEARING SERVICE

The following procedures, except oil seal replacement, require the engine to be disassembled. See "Engine Disassembly Procedure" in this chapter.

Cylinder Cover

Clean and inspect the cover, looking for wear 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 cover screw threads and torque the cover screws to the recommended specification. Always use new gaskets and new oil seals installed using seal protectors after the cover is removed.

Oil Seal Service

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 COVER. ATTEMPTING TO INSTALL THE SEAL TOO FAR IN CAN CAUSE DAMAGE TO 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, remove the old oil seals by tapping them out with a screwdriver or punch from the inside. If the crankshaft is in place, remove the seal by using the proper oil seal puller (diag. 50).

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 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. 51).

CRANKSHAFT BEARING SERVICE

Ball Bearing Service

Remove the two bearing retainer screws and washers. Remove the ball bearing in the cylinder cover by pressing the bearing from the outside of the cover toward the inside using an arbor press.

Install a new ball bearing by pressing the bearing from the inside of the cover toward the outside until the bearing contacts the shoulder. Install the two bearing retainer screws with washers and tighten to 45 in. lbs. (5.0 Nm) of torque.

OIL SEAL

OIL SEAL DRIVER 670272

OIL SEAL DRIVER PROTECTOR

OIL SEAL REMOVED

SNAP RING

SERVICE BUSHING

We are supplying this bushing for service repair. After the bushing has been installed, it requires line reaming to the proper size.

Following the chart below, have a reputable machine shop do this work for you.

BUSHING SIZE CHART

BUSHING SERVICE FINISHED REAM

PART NUMBER BORE DIAMETER

30979 .............................................................. .8755 - .8760" (22.226 - 22.250 mm)

31461 .............................................................. 1.0000 - 1.0005" (25.4 - 25.413 mm)

31462 .............................................................. 1.0000 - 1.0005" (25.4 - 25.413 mm)

31546 .............................................................. 1.0000 - 1.0005" (25.4 - 25.413 mm)

33368 .............................................................. 1.1880 - 1.1890" (30.175 - 30.2 mm)

34836 .............................................................. 1.0005 - 1.0010" (25.413 - 25.425 mm)

34837 .............................................................. 1.0005 - 1.0010" (25.413 - 25.425 mm)

35377 .............................................................. 1.3765 - 1.3770" (34.950 - 34.976 mm)

35400 .............................................................. 1.3765 - 1.3770" (34.950 - 34.976 mm)

ENGINE ASSEMBLY

The following procedures apply to most engine models. Actual procedure may vary.

1. Use new gaskets and seals at all locations. Clean all internal engine parts with solvent and blow dry with compressed air or allow to dry.

OIL SEAL PROTECTOR

2. Using the correct seal protector (see Chapter 11 under "Tools"), apply engine oil to the crankshaft bearing surfaces and insert the tapered end of the crankshaft in the crankcase. Slide the crankshaft in until it bottoms.

3. Apply engine oil to the piston skirt, rings, connecting rod bearing surface, and the cylinder bore. Using a band type ring compressor, stagger the ring end gaps, compress the rings, and push the piston assembly into the cylinder with the match marks on the connecting rod facing out of the crankcase and the arrow on the top of piston or on the piston skirt pointing toward the push rod location or the carburetor side of the engine if applicable. Push the piston assembly in until the rod is positioned on the crankshaft rod journal surface.

4. Align the match marks on the rod cap and rod, install the rod cap bolts and dipper if applicable and tighten the bolts in equal increments to the specified torque.

MATCH MARKS

DURLOCK BOLT

5. Assemble the compression release

components to the camshaft on engine models OHH and OHSK50-70. Install spring end "A" through the release from the pin side, insert spring end "B" through the camshaft gear, and slide the release pin in the small hole near the center of the cam gear. Assemble the thrust washer on the camshaft next to the compression release. (diag. 55)

NOTE: Some OHH models used on chipper/ shredders may not require compression release mechanisms.

COMPRESSION RELEASE

CAMSHAFT

COMPRESSION RELEASE SPRING

THRUST WASHER

A INSERT SPRING END "A"

6. Some OHV11 - 17 engines come equipped with a spin on oil filtration system. If the engine is not equipped with a filter, one may be added IF THE SUMP HAS AN OIL PASSAGE COVER. The kit part number 36435A should be ordered to upgrade the engine if desired.

7. Install the lifters, camshaft, barrel and plunger style oil pump (chamfered side toward the gear) if applicable, ultra-balance shaft or dual balance shafts if applicable. Align the timing mark or notched tooth on the crankshaft gear to the mark or hole in the camshaft gear. If equipped, time the Ultra-balance® with the piston at Top Dead Center (T.D.C.). Slide the drive gear over the keyway in crankshaft while aligning the timing marks on the gears.

DRIVE GEAR, CRANKSHAFT

MATCH MARK

THINNER GEAR

THICKER GEAR

OIL PUMP SHAFT

SCREW

CHAMPFER UP TOWARD CAM

GASKET

OIL PASSAGE GASKET

OIL PUMP ASSY.

"O" RING

OIL PUMP COVER

SCREW

OIL FILTER

OIL PASSAGE COVER

DUAL SHAFT COUNTERBALANCE

a. Dual Balance Shaft

Time the dual shaft counterbalance system with the piston at T.D.C. Install the counterbalance with the thicker gear in the far right boss in the crankcase and the other counterbalance shaft with the thinner gear in the far left boss while aligning the timing marks. Slide the drive gear over the keyway in the crankshaft while aligning the timing mark with the thicker counterbalance gear.

NOTE: Engines equipped with rotary oil pumps must have the drive shaft and pump assembled after the sump cover is installed.

ULTRA-BALANCE TIMING

CAM TIMING

8. Mount the cylinder cover or flange with the governor gear assembly installed to the crankcase using dowel pins to position the cover and a new gasket. Install the cover down onto the crankcase and slightly rotate the crankshaft to allow the governor gear to mesh. Do not force. Apply a drop of blue Loctite 242 to the cover screw threads and tighten to the specified torque.

On engines with ball bearings in the cover, install a thrust washer (if applicable) over the crankshaft, followed by the retaining ring.

SHAFT

ROTOR

On OHV 13.5 -17 engines, install the oil pump drive shaft into the slot in the end of the camshaft. Apply engine oil and install the oil pump ring and rotor, followed by a new "O" ring and the pump cover. Tighten the screws to 50-70 inch pounds (5.5 - 8 Nm) torque.

9. Install the breather assembly.

10. Rotate the crankshaft to place the piston at Top Dead Center (TDC) on the compression stroke.

NOTE: Always cut the valve seats, never only lap the seats.

11. Pre-assemble the valves and spring assemblies into the cylinder head on all engine models EXCEPT OHM, OHSK80-130, OVM, OVXL (diag. 65 on page 79). Use a small block to support the valves tight to their seats while placing the head on a flat surface. For models OHH and OVRM, install the springs (dampening coils toward the head) and retainers on the valves and use fingers to compress the springs until the notch in the retainer is located in the notch in the valve stem. Repeat the procedure for other valve.

RING

NOTE: INSTALL OIL PUMP AFTER THE SUMP IS ON

ROTARY PUMP

For OHV models, place the springs (dampening coils toward the head) over the valve guide and place the valve caps on the springs with the larger opening away from the springs. Use spring compressor tool part # 670315A installed on a rocker arm stud, and either turn the stud in or secure with a locking nut as shown so about 1-1/2" (38.1 mm) of the stud is exposed. Compress the spring and install the valve retainers to lock the valve to the valve cap. Repeat the procedure for other valve.

Install the cylinder head using a new head gasket. On OHV 11-13 models, place the push rods in the block before installing the head and head gasket. Tighten the head bolts in the numbered sequence using 60 inch pound (6.8 Nm) increments to the specified torque.

NOTE: Tecumseh strongly recommends you order a complete seal kit. Replace all "O" ring and gaskets in kit.

RETAINERS HELD BY SPRING TENSION AGAINST THE CAP

RETAINER

CAP

VALVE SPRING COMPRESSOR TOOL PART NO. 670315

12. STEPS 12A -12G APPLY ONLY TO EARLY

PRODUCTION ENGINE MODELS OHM, OHSK120, OVM AND OVXL. CONTINUE

WITH STEP 13 FOR CURRENT PRODUCTION MODELS.

a. Install the push rods with the cupped ends

of the rods placed on top of the lifters. Visually check correct placement through the valve box opening. Use lubricated new "O" ring seals for both ends of the push rod tubes and install the push rod tubes in the crankcase.

b. Install the valves into the head, and using a

new head gasket, place the head on the cylinder block. Tighten the head bolts in the numbered sequence using 60 inch pound (6.8 Nm) increments to the specified torque.

FREE LENGTH

1.980" (50.292 mm) ALL OTHERS

OVRM/OHH 1.105 (28.067 mm)

(BLACK)

DAMPENING COILS LOCATED CLOSER TOGETHER

THIS END MUST FACE TOWARD THE STATIONARY PART OF THE ENGINE

(CYLINDER HEAD)

c. Install the rocker arm housing, push rod

guide plate with the legs facing up, new rocker arm studs with "O" rings under the guide plate. Install the valve box to head retaining screw using a flat washer and a new "O" ring. Tighten the screw and the studs to the specified torque.

d. Lift each valve up until it contacts the seat

and hold the valve in this position. Use a 12 inch (30.5 cm) piece of fuel line and wedge one end on each side of the valve stem through the port opening to hold the valve.

e. Bolt the valve spring compressor tool part

# 670315A on a rocker arm stud using the rocker arm bearing and locking nut (diag.

66).

f. Install the new o-rings (white o-ring on the

exhaust guide) followed by valve spring caps, valve springs with the dampening coils toward the head, (diag. 64) and valv e spring retainers with the larger opening awa y from the engine.

TEFLON EXHAUST (WHITE)

OVM / OHM STYLE

RETAINERS HELD BY SPRING TENSION AGAINST THE CAP

CAP

"O" RINGS

RETAINER

VALVE SPRING COMPRESSOR TOOL PART NO. 670315

g. Compress the valve spring with the tool and

insert the two retainers into the keeper so the inside ridge of the retainer locks into the valve stem groove. Repeat the procedure for the other valve (diag. 66).

NOTE: TORQUE THE CYLINDER HEAD

FOLLOWING THE SEQUENCE ON PAGE 69.

13. On engine models OHH and OVRM, install the push rods on the lifters, and rocker arms and lock nuts on the rocker arm pivot screws. Fasten the screw to the head with the push rod guide plate tabs facing up. Turn the screws in until slight play exists between the valve stem and rocker arm.

On OHM, OHSK120, OVM, and OVXL models, install the rocker arms, rocker arm bearings, and new rocker arm adjusting nuts on the studs. Tighten the adjusting nut until slight play exists.

On OHV 11-13, OHSK80-130, OHV110-145 models, install the push rods on the lifters, place the rocker arms on the rocker arm screws followed by the locking nut, washer, and push rod guide plate (with the tabs up). Turn the screws in until slight play exists between the valve stem and rocker arm.

On OHV13.5 -17 models, install the guide plate with the rocker arm studs and torque to 190 in. lbs. (21.5 Nm). Insert the push rods in the lifter sockets with the longer steel end toward the rocker arms. Place the rocker arms onto the studs with the socket end toward the push rod and thread the rocker arm bearings on until excessive play is removed.

"O" RING OR GASKET

3/16" ALLEN WRENCH

7/16" CROWFOOT WRENCH

OHH / OVRM

LOCKING / ADJUSTING NUT

CROWN DOWN

14. Set the valve lash with the engine cold, the piston at T.D.C., and both valves closed. Insert the specified feeler gauge between the rocker arm and valve stem. Adjust until a slight sliding drag is felt.

On models OHH and OVRM, lock this position by holding an 3/16" Allen wrench on the pivot ball screw while tightening the lock nut to 120 in. lbs. (13.5 Nm) of torque. A 7/16" crowfoot will be needed to torque the lock nut. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. 67).

On models OVM, OHM, OHSK120 and OVXL, with a 1/2" crowfoot, tighten down the rocker arm studs to 190 in. lbs. (21.5 Nm). Adjust the rocker arm hex nut with a 1/2" wrench to set the correct valve lash and tighten the locking jam nut to 18 in. lbs. (2 Nm). Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. 68).

On models OHV 11-13, OHSK80-130, OHV110-145, hold the rocker arm pivot bearing using a 7/16" wrench or socket while using a 1/2" crowfoot to tighten the lock nut to 120 in. lbs (13.5 Nm) of torque. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. 69).

FEELER

GAUGE

VA L VE STEM

ROCKER ARM

STUD

OVM / OHM / O VXL

PUSH ROD

GUIDE

T ABS UP

7/16"

SOCKET WRENCH

1/2"

CROWFOOT

WRENCH

OHV 11-13 and OHV 110-135 / OHSK80-130

On models OHV 135 - 175 hold a 1/2" wrench on the rocker arm bearing while tightening the 5/32" Allen head set screw to 75 in. lbs. (8.5 Nm) of torque. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. 70).

Current production models OHV135 - 175 use a 1/2" wrench to tighten the rocker arm bearing to the correct valve lash. Once adjusted use a 1/2" socket and torque the jam nut to 130 inch pound (14.7 Nm). Rotate the crankshaft one full turn to check push rod movement and correct valve lash (diag. 71).

15. Install the rocker arm cover using a new gasket or o-ring and tighten the screws to the specified torque. Connect the breather hose to the valve cover fitting on model OHH.

16. Attach the backing plates or baffles. Attach the governor arm lever if removed.

17. Attach the alternator coil if applicable and route the wires away from the flywheel area.

18. Install the flywheel spacer if applicable, flywheel key, flywheel, starter cup (if applicable), bevelled washer (concave surface in), and flywheel nut. Use strap wrench part # 670305 to hold the flywheel and tighten the nut to the specified torque.

19. Install the ignition module using a part # 670297 .0125" (.3175 mm) air gap tool between the flywheel magnets and the laminations of the module (diag. 72). Tighten the mounting screws, remove the tool, and check for contact while rotating the flywheel. None should be found. Attach the ignition ground lead to the module terminal.

1/2"

TORQUE

WRENCH

OHV135 - 175

5/32"

ALLEN

WRENCH

1/2"

WRENCH

1/2"

WRENCH

20. Install the blower housing on all engines with the speed control mounted on the blower housing or engine block, and attach the ignition groundout lead at the control if applicable.

21. Install the intake pipe, speed control, carburetor, and air cleaner assembly while hooking the throttle and governor linkage. Install the blower housing on all engines with intake pipe mounted speed control brackets. Check the governor and speed control hookup and adjustment - see Chapter 4 under "Service".

.0125" (.3175 mm)

AIR GAP

22. Attach the fuel tank (if applicable) using bolts or wedging the tank in the blower housing slots provided. Attach the fuel line and secure with clamps.

23. Slide the fuel line on the carburetor fitting and secure with a clamp. Slide the breather tube on the carburetor or air cleaner fitting if applicable.

NOTE: If the tank is supplied by the O.E.M. replace the fuel filter. Tecumseh's tanks have a fuel filter in the tank and service is not necessary.

24. Fill the engine with oil to the full mark on the dipstick. Add fresh fuel to the fuel tank and secure the cap.

25. Install the spark plug and high tension lead. Mount the engine to the equipment and connect wiring and control cables. OVRM rotary mower engines require the blade to be secured to the blade hub adapter and crankshaft before attempting to start the engine.

26. Start the engine and allow it to run approximately five minutes to reach operating temperature. Optimize the carburetor if adjustable, verify top no load and idle RPM settings.

REMOVE

BOLTS

SLIDE TANK

CHAPTER 10

ENGINE SPECIFICATIONS AND

SEARS CRAFTSMAN CROSS-REFERENCE

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.

OVERHEAD VALVE SEARS CRAFTSMAN CROSS REFERENCE

Craftsman Tecumseh

143.366012 OVM120-200004

143.366072 OVM120-200006

143.366202 OVM120-200012

143.366212 OVM120-200014A

143.366232 OVM120-200015A

143.376012 OVM120-200017A

143.376032 OVM120-200012A

143.376072 OVM120-200006A

143.376082 OVM120-200018A

143.384132 OVRM905-42002

143.384142 OVRM905-42003

143.384152 OVRM905-42001

143.384162 OVRM905-42004

143.384182 OVRM905-42005

143.384192 OVRM905-42006

143.386012 OVM120-200020B

143.386032 OVM120-200006B

143.386092 OVM120-200014B

143.386102 OVM120-200018B

143.386152 OVM120-200015B

143.386162 OVM120-200022A

143.394092 OVRM905-42008

143.394102 OVRM905-42010

143.394112 OVRM905-42011

143.394192 OVRM905-42007

143.394202 OVRM905-42009

143.394212 OVRM905-42012

143.396012 OVXL120-202031C

143.396032 OVXL120-202036C

143.396062 OVXL120-202034C

143.396072 OVXL120-202035C

143.396092 OVM120-200023C

143.396112 OVXL120-202039C

143.396132 OVXL120-202040C

143.404112 OVRM50-52901

143.406012 OVXL120-202040D

143.406052 OVXL120-202034D

143.406062 OVXL120-202035D

143.406072 OVXL120-202047D

143.406132 OVXL120-202039D

143.406142 OVXL120-202049D

Craftsman Tecumseh

143.406152 OVXL120-202050D

143.406162 OVXL125-202051D

143.414432 OVRM50-52901A

143.416012 OVXL120-202056D

143.416042 OVXL125-202401

143.416082 OVXL125-202403

143.426092 OVXL120-202063E

143.426112 OVXL120-202062E

143.426122 OVXL125-202064E

143.426142 OVXL120-202034E

143.426152 OVXL120-202039E

143.426172 OVXL125-202067E

143.436032 OHV125-203013A

143.436042 OHV125-203012A

143.436092 OHV125-203015A

143.436102 OHV125-203018A

143.436132 OHV125-203020A

143.436152 OHV125-203023A

143.796112 OHSK120-222005

143.806062 OHSK120-222005A

143.816042 OHSK120-222007B

143.836052 OHSK120-222015C

143.941200 OHV125-203023B

143.941201 OHSK120-222015D

143.951600 OHV165-204402B

143.951602 OHV165-204403B

143.955003 OHH50-68001A

143.955007 OHH50-68004A

143.961201 OHSK120-222026E

143.965007 OHH50-68001B

143.965009 OHH50-68036B

143.965011 OHH50-68044B

143.965013 OHH50-68004B

143.965015 OHH50-68060B

143.965017 OHH50-68060C

143.965019 OHH50-68044C

143.965021 OHH50-68036C

143.965023 OHH50-68004C

143.965501 OHH55-69020A

143.965503 OHH55-69020B

Craftsman Tecumseh

143.971200 OHV125-203023C

143.971201 OHSK120-222026F

143.971300 OHV135-206901A

143.975003 OHH50-68044D

143.975005 OHH50-68004D

143.975009 OHH50-68113D

143.975501 OHSK55-69507A

143.975503 OHSK55-69509A

143.976001 OHH60-71101A

143.981200 OHV125-203023D

143.981201 OHSK120-223609A

143.985001 OHH50-68036F

143.985005 OHH50-68113F

143.985501 OHH55-69020E

143.985503 OHSK55-69514B

143.985505 OHSK55-69514C

143.986001 OHH60-71101C

143.986003 OHH60-71116C

143.986702 OVRM65-22016B

143.986704 OVRM65-22017B

143.986714 OVRM65-22020B

143.986716 OVRM65-22026B

143.986718 OVRM65-22029B

143.991200 OHV125-203050D

143.991201 OHSK125-223701A

143.991203 OHSK125-223702A

143.991300 OHV13-203211B

143.995007 OHH50-68004F

143.996001 OHH60-71138C

143.996005 OHH60-71140C

143.996007 OHH60-71146C

143.996009 OHH60-71167C

143.996501 OHSK65-71901A

143.996503 OHSK65-71902A

143.996505 OHH65-71702A

143.996507 OHH65-71704A

143.996702 OVRM105-21024E

ENGINE SPECIFICATIONS

OVRM40 OVRM50-6.75 OVRM120 OHH50

Specifications OVRM105 OHSK50

Standard Metric Standard Metric Standard Metric Standard Metric

English mm English mm English mm English mm

Displacement (in

Stroke 1.844 46.838 1.938 49.225 1.938 49.225 1.938 49.225 Bore 2.500 63.500 2.625 66.675 2.795 70.993 2.625 66.675

Ignition Module Air Gap .0125 .3175 .0125 .3175 .0125 .3175 .0125 .3175 Spark Plug Gap .030 .762 .030 .762 .030 .762 .030 .762 Valve Clearance In./Ex. .004 .1016 .004 .1016 .004 .1016 .004 .1016

Valve Seat Angle 46 Valve Seat Width .035 .889 .035 .889 .035 .889 .035 .889

Valve Guide Oversize Dimension .2807 .2787 7.130 7.079 .2807 ..2787 7.130 .7.079 .2807 ..2787 7.130 .7.079 .2807 7.135

Crankshaft End Play .006 .1524 .006 .1524 .006 .1524 .006 .1524

Crankpin Journal Dia. .8610 31.869 .9995 25.362 .9995 25.362 .9995 25.362

Crankshaft Dia. Flywheel .9985 25.362 .9985 25.362 .9985 25.362 .9985 25.362 End Main Brg. .9990 25.375 .9990 25.375 .9990 25.375 .9990 25.375

Crankshaft Dia. .9985 25.362 1.0005 25.413 1.0005 25.413 .9985 25.362 P.T.O. Main Brg. .9990 25.375 1.0010 25.425 1.0010 25.425 .9990 25.375

Conn. Rod Dia. Crank Brg. 1.0005 25.413 1.0005 25.413 1.0005 25.413 1.0005 25.413

Camshaft Bearing Diameter .4975 12.637 .4975 12.637 .4975 12.637 .4970 12.624

Piston Dia. Bottom of Skirt 2.4950 63.373 2.6204 66.558 2.6204 66.558 2.6204 66.558

Ring Groove Side Clearance .0020 .051 .0020 .051 .0020 .051 .0020 .051 1st & 2nd Comp. .0050 .127 .0050 .127 .0050 .127 .0050 .127

Ring Groove Side Clearance .0050 .013 .0050 .013 .0050 .013 .0050 .013 Bottom Oil .0035 .089 .0035 .089 .0035 .089 .0035 .089

Piston Skirt to Cylinder .0040 .102 .0030 .076 .0030 .076 .0030 .076 Clearance .0058 .147 .0056 .142 .0056 .142 .0056 .142

Ring End Gap .010 .254 .010 .254 .010 .254 .007 .178

Cylinder Main Bearing 1.0005 25.413 1.0005 25.413 1.0005 25.413 1.0005 25.413 Diameter 1.0010 25.425 1.0010 25.425 1.0010 25.425 1.0010 25.425

Cylinder Cover / Flange 1.0050 25.413 1.0050 25.413 1.0050 25.413 1.0050 25.413 Main Brg. Diameter 1.0010 25.425 1.0010 25.425 1.0010 25.425 1.0010 25.425

) (cc) 9.06 148.50 10.49 171.93 11.9 195.04 10.49 171.93

Note (A) Note (A) Note (A) Note (A)

2.501 63.525 2.626 66.700 2.796 71.018 2.626 66.700 Note (B) Note (B) Note (B) Note (B)

.004 .1016 .004 .1016 .004 .1016 .004 .1016

.045 1.143 .045 1.143 .045 1.143 .045 1.143

INT. EX. INT. EX. INT. EX. INT. EX. INT. EX. INT. EX.

.2817 .2797 7.155 7.104 .2817 .2797 7.155 7.104 .2817 .2797 7.155 7.104 .2817 7.155

.027 .6858 .027 .6858 .027 .6858 .027 .6858

Note (C) Note (C) Note (C) Note (C) Note (C) Note (C) Note (C) Note (C)

.8615 21.882 1.000 25.400 1.000 25.400 1.000 25.400

1.0010 25.425 1.0010 25.425 1.0010 25.425 1.0010 25.425

.4980 12.649 .4980 12.649 .4980 12.649 .4975 12.637

2.4520 63.378 2.6220 66.599 2.6220 66.599 2.6220 66.599

.020 .508 .020 .508 .020 .508 .017 .432

Note A: OVRM60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a displacement

of 11.9 (195.04).

Note B: All OVRM 60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a

2.795"/2.796 (70.993/71.018) Bore.

Note C: All engines equipped with a ball bearing will have "0" End Play.

ENGINE SPECIFICATIONS (Continued)

OHH and OHSK80 - 110 OHM, OHSK, OVM, OHV13.5 - 17

OHSK55 - 70 OVXL120,130

Specifications Note (D) & OHV11-13

Standard Metric Standard Metric Standard Metric Standard Metric

English mm English mm English mm English mm Displacement (in2) (cc) 11.9 195.04 19.43 318.46 21.82 357.63 29.9 490.06 Stroke 1.938 49.225 2.532 70.993 2.532 70.993 3.00 76.6 Bore 2.795 70.993 3.125 79.375 3.312 84.125 3.562 90.475

2.796 71.018 3.126 79.400 3.313 84.150 3.563 90.500 Ignition Module Air Gap .0125 .3175 .0125 .3175 .0125 .3175 .0125 .3175 Spark Plug Gap .030 .762 .030 .762 .030 .762 .030 .762 Valve Clearance In./Ex. .004 .1016 .004 .1016 .004 .1016 .004 .1016

.004 .1016 .004 .1016 .004 .1016 .004 .1016

Valve Seat Angle 46

Valve Seat Width .035 .889 .035 .889 .035 .889 .042 1.0671

.045 1.143 .045 1.143 .045 1.143 .052 1.321

Valve Guide Oversize .2807 7.130 .3432 8.717 .3432 8.717 .3432 8.717 Dimension .2817 7.155 .3442 8.743 .3442 8.743 .3442 8.743

Crankshaft End Play .006 .1524 .002 .051 .002 .051 .0025 .064

.027 .6858 .042 .067 .042 .067 .0335 .851

Note (C) Note (C)

Crankpin Journal Dia. .9995 25.362 1.3740 34.900 1.3740 34.900 1.6223 41.206

1.000 25.400 1.3745 34.912 1.3745 34.912 1.6228 41.219 Crankshaft Dia. Flywheel .9985 25.362 1.3745 34.912 1.3745 34.912 1.6245 41.262

End Main Brg. .9990 25.375 1.3750 34.925 1.3750 34.925 1.6250 41.275 Crankshaft Dia. .9985 25.362 1.3745 34.912 1.3745 34.912 1.6245 41.206

P.T.O. Main Brg. .9990 25.375 1.3750 34.925 1.3750 34.925 1.6250 41.275 Conn. Rod Dia. Crank Brg. 1.0005 25.413 1.3775 34.988 1.3775 34.988 1.6234 41.234

1.0010 25.425 1.3780 35.001 1.3780 35.001 1.6240 41.250 Camshaft Bearing Diameter .4970 12.624 .6230 15.824 .6230 15.824 .6235 15.837

.4975 12.637 .6235 15.837 .6235 15.837 .6240 15.850

Piston Dia. Bottom of Skirt 2.7904 70.876 3.1195 79.235 3.3095 84.061 3.5595 90.411

2.7920 70.917 3.1205 79.261 3.3105 84.087 3.5605 90.437 Ring Groove Side Clearance .0020 .051 .0020 .051 .0020 .051 .0020 .051

1st & 2nd Comp. .0050 .127 .0040 .127 .0040 .127 .0040 .127 Ring Groove Side Clearance .0050 .013 .0010 .0254 .0010 .0254 .0009 .0229

Bottom Oil .0035 .089 .0030 .076 .0030 .076 .0029 .074 Piston Skirt to Cylinder .0030 .076 .0015 .038 .0015 .038 .0015 .038

Clearance .0056 .142 .0035 .089 .0035 .089 .0030 .089 Ring End Gap .007 .178 .010 .254 .010 .254 .012 .305

.017 .432 .020 .508 .020 .508 .022 .559

Cylinder Main Bearing 1.0005 25.413 1.3765 34.963 1.3765 34.963 1.6265 41.313 Diameter 1.0010 25.425 1.3770 34.976 1.3770 34.976 1.6270 41.326

Cylinder Cover / Flange 1.0050 25.413 1.3765 34.963 1.3765 34.963 1.6265 41.313 Main Brg. Diameter 1.0010 25.425 1.3770 34.976 1.3770 34.976 1.6270 41.326

Note A: OVRM60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a displacement

of 11.9 (195.04).

Note B: All OVRM 60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a

2.795"/2.796 (70.993/71.018) Bore. Note C: All engines equipped with a ball bearing will have "0" End Play. Note D: For OHSK110 models with specification number starting with 223000 have a displacement of

21.82 ( 357.63 cc).

OVERHEAD VALVE TORQUE SPECIFICATIONS

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.

Specifications below ten ft. lbs. torque are listed only as in. lb. measurements to encourage the use of an inch pound torque wrench for greater torque accuracy.

.tf

.sbl.nI

stloBdaeHrednilyC

0329162X X X X X X

stloBdoR.nnoC

501-21X X

stloBdoR.nnoC

0223.818.42XXXX

egnalFrorevoC.lyC

5115.931X X

egnalFrorevoC.lyC

5215.0141XXXX

tuNleehwylF

0545315X X

norItsaCtuNleehwylF

0556426X

tuNleehwylF

0078597XXXX

gulPkrapS

0521282X X X X X X

).lyCottceriD(gnitnuoM.ngI

54-5X X

)dutSottceriD(gnitnuoM.ngI

54-5 X X X X

.lyCotdutSgnitnuoM.ngI

04-5.4XXXX

daeHotepiPekatnI

511-31X X X X X X

epiPekatnIotroterubraC

07-8X X X X X X

otdioneloSffOtuhSleuF

71-2 X X X

.braC

)degnalF(.gtMrelffuM

57- 5.8X

mNMRVO

.sbl

56-05HHO

07-05KSHO

,LXVO

,MHO

&,MVO

KSHO

VHO

31-11

VHO

531-011

seireS602

541-531VHO

seireS302

5.71-51VHO

seireS402

).tceR(.gtMrelffuM

56- 5.7X

.gtMrelffuM

54-5X

)lavO(

.gtMrelffuM

001- 5.11X

dlofinaMot)degnalF(relffuM

0025.615.22XX

)degnalF(

dlofinaMotpmalCrelffuM

08-9 X

TORQUE SEQUENCE

OVRM / OHH, OHSK

FLAT WASHER

BELLEVILLE WASHER

(CROWN TOWARD BOLT HEAD)

TORQUE SEQUENCE

OHV 11 - 17, OHM, OVM, OHSK110 - 120

OVERHEAD VALVE TORQUE SPECIFICATIONS

Specifications below ten ft. lbs. torque are listed only as in. lb. measurements to encourage the use of an inch pound torque wrench for greater torque accuracy.

.nI

.sbl.sbl.tfM/NMRVO

)tloBredluohS(.gtMdlofinaM

0615.3181XXXX

retratSlioceR

52-3X

retratSlioceR

05-5.5XXX

retratSlioceR

04-5.4X

retratSlioceR

089 XXXX

rednilyCotretratScirtcelE

001-11XXXX

rednilyCotretratScirtcelE

0515.2171XX

tuNmaJxeHmrArekcoR

81-2 X 1X

nellAkcoLmrArekcoR

57- 5.8X

wercS

tuNmaJgnitsujdArekcoR

0318.017.411X

tuNkcoLdutSmrArekcoR

021015.31XXX1X1X

sdutSmrArekcoR

0918.515.12XXX

revoCxoBrekcoR

04-5.4X X

revoCxoBrekcoR

81-2 X

revoCxoBrekcoR

55-6 X X X

)swercs4(

rednilyCot.yssAlioC.tlA

52-3 X

rednilyCot.yssAlioC.tlA

56-7 X

rednilyCot.yssAlioC.tlA

09-01XXX

noitanimaLot.yssAlioC.tlA

03-5.3X

56-05HHO

07-05KSHO

,LXVO

,MHO

MVO

&KSHO

VHO

31-11

VHO

531-011

seireS602

541-531VHO

seireS302

5.71-51VHO

seireS402

NOTE 1: A jam nut is described as a nut which is placed above the rocker arm and bearing. A lock nut is

positioned below the rocker arm and bearing.

CHAPTER 11. EDUCATIONAL MATERIALS

AND TOOLS

AVAILABLE TECHNICIAN'S HANDBOOKS

692508

Covers the diagnosis and repair of Tecumseh 2-cycle

engines. Except the TC Engine and TVS840.

692509

Covers the diagnosis and repair of the Tecumseh

4-cycle light/medium frame engines.

691462A

Covers the diagnosis and repair of Tecumseh 4-cycle

large frame engines.

691218

Covers the diagnosis and repair of Peerless® power

train components.

694782

Contains technical information for the repair of the TC

series, 2-cycle engines.

694988

Contains diagnosis and technical information for the

repair of TVS840, HSK/HXL845/850, 2-cycle engines.

695244A

Covers the diagnosis and repair of the OVRM/OVM/

OHM/OHV 4-cycle overhead valve engines.

695578

Covers the diagnosis and repair of the Vector Series,

4-cycle engines.

AVAILABLE FOREIGN TECHNICIAN'S

HANDBOOKS

694732 Spanish

This manual covers the following models:

VH80, VH100, HH80, HH100, HH120, OH120-180

Model numbers are located on the engine shroud.

695555 Spanish

Covers the diagnosis and repair of the Tecumseh

4-cycle light/medium frame engines.

695657 German

Covers the diagnosis and repair of the Tecumseh

4-cycle light/medium frame engines.

695562 French

Covers the diagnosis and repair of the Tecumseh

4-cycle light/medium frame engines.

VIDEO PROGRAMS

695015

Carburetor Troubleshooting. Covers identification of

carburetors used on Tecumseh engines and how to

troubleshoot and repair them. VHS only.

695059

Understanding Tecumseh Ignition Systems. A basic

program designed to give the small engine technician

first hand knowledge of Tecumseh ignition systems so

the technician can understand the system and perform

repairs to it. VHS only.

695148

Teardown and reassembly of the 900 series transaxles.

This video will show a complete step-by-step procedure

for teardown and reassembly of the 900, 910 and 920

series transaxles.

695185

Electrical Troubleshooting. This video training program

will assist the small engine technician in the proper

procedures for troubleshooting electrical systems on

outdoor power equipment.

695285

An in-depth look at the 800 series transaxles. Detailing

the teardown and reassembly procedures for the 800,

801 and 820 transaxles.

SPECIAL BOOKLETS

INSTRUCTIONAL GUIDE 692738

Assists in the use and understanding of the Tecumseh

Master Parts Manual. Illustrates time saving features

incorporated into the manual. Explains new carburetor

parts breakdown format.

4-CYCLE ENGINE FAILURE ANALYSIS 695590

This booklet is designed as a tool for the average

technician to correctly assess the cause of failure.

CARBURETOR TROUBLESHOOTING BOOKLET 695907

This booklet is designed as a quick reference to

carburetion problems and related repair procedures.

IGNITION SYSTEMS TROUBLESHOOTING BOOKLET 694903

This booklet contains information on the identification,

possible problems and related repair procedures of

Tecumseh Ignition Systems.

SPECIAL TOOLS BOOKLET 694862

This booklet depicts all specialty tools offered by

Tecumseh which can be used on 2 and 4 cycle engines

and Peerless units.

QUICK REFERENCE CHART BOOKLET 695933

This booklet contains the quick reference information

found on Tecumseh wall charts.

This booklet is designed to be used as a work bench

quick reference guide when servicing Tecumseh

engines and motion drive systems.

TESTER BOOKLETS

694529

Test procedures for Tecumseh electrical components

using Graham-Lee Tester 31-SM or 31-SMX-H.

694530

Test procedures for Tecumseh electrical components

using Merco-O-Tronic Tester 9800. (Tests are similar

for 98, 98A and 79.)

TOOLS

TOOL KIT 670195E

Kit contains tools for 2- and 4-cycle engines.

Includes all items on this page but items may be purchased separately.

OIL SEAL DRIVER

No. 670195D Tool Kit. Contains special tools

commonly used in servicing 2 and 4 cycle engines.

OIL SEAL REMOVER

Consult the specification chart or measure the shaft

diamteter to determine the correct tool.

OIL SEAL PROTECTOR/INSTALLER

Consult the specification

chart or measure the shaft

diamteter to determine the

correct tool.

Use with: No. 670260. 1-3/16" crankshaft bearing diameters. No. 670261. 13/16" crankshaft bearing diameters. No. 670262. 3/4" Crankshaft bearing diameters. No. 670263. 5/8" extended camshaft. No. 670264. 1/2" extended camshaft. No. 670277. 35/64" 8-1/2:1 Aux. Shaft. No. 670292. 1" crankshaft bearing diameters assy.

for recessed, raised, or flush seal position.

No. 670293. 7/8" crankshaft bearing diameters

assy.for recessed or flush seal position.

No. 670308. Adapter for raised or flush seal position,

used with 670309.

No. 670309. 1-3/8" crankshaft bearing diameters

protector, use with 670308.

No. 670310. 1-3/8" crankshaft bearing diameter for

recessed seal position.

No. 670330. 1-1/2" extended camshaft. No. 670335. 1-1/8" crankshaft bearing diameters. No. 670336. 1-1/8" crankshaft bearing diameter

recessed seal.

No. 670337. 1" to be used with 670265 and 670266

recessed and raised.

Use with: No. 670287. 7/8" crankshaft bearing diameters. No. 670288. 3/4" crankshaft bearing diameters. No. 670289. 13/16" crankshaft bearing diameters. No. 670290. 1" crankshaft bearing diameters. No. 670312.1-3/8" crankshaft bearing diameters. No. 670331.1.5" crankshaft bearing diameters.

VIBRATION TACHOMETER

No. 670156 Vibration tachometer.

TAPER GAP GAUGE

FLYWHEEL KNOCK-OFF TOOL

No. 670103 - Knock-off tool (right hand) (7/16"). No. 670169 - Knock-off tool (right hand) (1/2"). No. 670314 - Knock-off tool (right hand) (5/8"). No. 670329 - Knock-off tool (right hand) (3/4").

No. 670256 Taper Gap Gauge

VALVE LAPPING TOOL

No. 670154A Valve lapping tool.

BUSHING TOOL KIT

OVRM AND OHV11-16.5 SPEED ADJUSTMENT TOOL

Rebushing tool kit for use on OHM, OHSK110, 120,

OVM, OHV11-13 AND OVXL. 1-3/8" main bearing.

A. None

B. None

C. No. 670311 - Bushing Driver/Installer.

No. 670317 - Bushing Driver/Installer.

No. 670326

TORX DRIVERS

Torx 8 670334

Torx 10 670333

Torx 15 670323

Torx 20 670324

Torx 25 670319

Torx 30 670320

No. 670298 Alignment Tool.

1/32" (.794 mm) OVERSIZE VALVE GUIDE REAMER

No. 670283. Used on OHH on Intake and Exhaust,

and OVRM40-60 Intake valve guide. Oversize

diameter .2807/.2817 (7.130 - 7.155 mm)

No. 670328. Used on OVRM40-60 Exhaust valve

guide. Oversize diameter .2787/.2797

(7.079 - 7.104 mm).

No. 670284. Used on OVXL/OVM/OHM120,

OVXL125 and OHV11-16.5 Intake and Exhaust.

Oversize diameter .3432/.3442 (8.717 - 8.743 mm).

RING EXPANDER

No. 670117

Tecumseh Parts

TECUMSEH OHH50 - 65, OHHSK50 - 130, OHV11, OVM120, OVRM40-675 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual