Onan T260G Service Manual

ONAN T260G ENGINE SERVICE MANUAL

Table of Contents – Page 1 of 2

SAFETY PRECAUT I O NS

GENERAL PROTECT AGAINST MOVING PARTS BATTERIES FUEL SYSTEM EXHAUST SYSTEM EXHAUST GAS IS DEADLY! COOLING SYSTEM KEEP THE UNIT AND SURROUNDING AREA CLEAN

INTRODUCTION EXHAUST GAS IS DEADLY!

GENERAL INFORMATION INTRODUCTION ENGINE MODEL REFERENCE

SPECIFICATIONS DIMENSIONS AND CLEARANCES ASSEMBLY TORQUES ENGINE TROUBLESHOOTING

OIL SYSTEM CRANKCASE OIL OIL FILTER CHANGE CRANKCASE BREAT HER PRESSURE LUBRICAT IO N

FUEL SYSTEM CARBURETOR CARBURETOR OVERHAUL PULSATING-DIAPHRAGM FUEL PUMP AIR CLEANER DASHPOT ADJUSTMENT GOVERNOR ADJUSTMENT

IGNITION AND BATTERY CHARGING BREAKER POINT IGNITION SYSTEM IGNITION TIMING ELECTRONIC IGNITION SYSTEM IGNITION TIMING BREAKER POINT AND ELECTRONIC IGNITION COILS SPARK PLUGS BATTERY INSPECTION BATTERY JUMP STARTIN G FLYWHEEL ALTERNAT OR ALTERNATOR OUTPUT TEST

STARTING SYSTEM ELECTRIC STARTER

ONAN T260G ENGINE SERVICE MANUAL

Table of Contents – Page 2 of 2

ENGINE DISASSEMBLY DISASSEMBLY/ASSEMBLY VALVE SYSTEM TAPPETS VALVE FACE AND SEAT GRINDING FLYWHEEL GEAR COVER GOVERNOR CUP TIMING GEARS PISTONS AND CONNECTING RODS CYLINDER BLOCK CRANKSHAFT BEARINGS CRANKSHAFT ENDPLAY CHECKING CONNECTING ROD BEARING CLEARANCE OIL SEALS PISTON ASSEMBLY INSTALLATION OF PISTON IN CYLINDER CYLINDER HEADS CYLINDER HEAD STUD TEST AND REPLACEMENT PROCEDURE ALIGNING BLOWER WHEEL, VENTURI AND CHAFF SCREEN

Service

Manual

Engine

Safety

It

is recommended that you read your engine manual and become thoroughly acquainted with your equipment before you start the engine.

Precautions

This symbol if used warns of imme-

diate hazards which will result in

severe personal injury or death.

WARNING

This symbol refers to a hazard or unsafe practice which can result in

severe personal injury or death.

Fuel System

DO

NOT fill fuel tanks while engine is running.

DO

NOT smoke or use an open flame in the vicinity of the engine or fuel tank. Internal combustion engine fuels are highly flammable.

Fuel lines must be of steel piping, adequately secured,

and free from leaks. Piping at the engine should be approved flexible line. Do not use copper piping for flexible lines as copper will work harden and become brittle enough

to

break.

CAUTION

personal injury or product or property damage.

Fuels, electrical equipment, batteries, exhaust gases and moving parts present potential hazards that can result in serious, personal injury. Take care in following these recommended procedures. All local, state and federal codes should be consulted and complied with.

This symbol refers to a hazard or

unsafe practice which can result in

Exhaust System

This engine is not designed or in-

k!!!!!!!!!!!

tended for use in any type of aircraft,

Use of this engine in aircraft can result in engine failure

and causes serious personal injury or death.

Exhaust Gas is Deadly!

General

Provide appropriate fire extinguishers and install them in convenient locations. Use an extinguisher rated ABC by NFPA.

Make sure that all fasteners on the engine are secure and accurately torqued. Keep guards in position over fans, driving belts, etc.

If it is necessary to make adjustments while the engine is running, use extreme caution when close to hot exhausts, moving parts, etc.

Protect Against Moving Parts

Do

not wear loose clothing in the vicinity of moving parts, such as PTO shafts, flywheels, blowers, couplings, fans, belts, etc.

Exhaust gases contain carbon monoxide, a poisonous gas that can cause unconsciousness and death. It is an odorless and colorless gas formed during combustion of hydrocarbon fuels. Symptoms of carbon monoxide poisoning are:

Dizziness Vomiting Headache Weakness and Sleepiness

If

you experience any of these symptoms, get out into fresh air immediately, shut down the unit and do not use until been inspected.

The best protection against carbon monoxide inhalation is proper installation and regular, frequent inspections complete exhaust system. If you notice a change in the sound or appearance immediately and have it inspected and repaired at once by a competent mechanic.

Be sure all fuel supplies have a positive shutoff valve.

Exhaust products of any internal combustion engine are toxic and can cause injury, or death applications, especially those within a confined area, should be equipped with an exhaust system to discharge gases to the outside atmosphere.

Do not use exhaust gases to heat a compartment. Make sure that your exhaust system is free of leaks.

Ensure that exhaust manifolds are secure and are not warped by bolts unevenly torqued.

of

exhaust system, shut the unit down

if

inhaled.

Muscular Twitching Throbbing in Temples

All

engine

it

has

of

the

Keep your hands away from moving parts.

Batteries

Before starting work on the engine, disconnect batteries

to

prevent inadvertent starting of the engine.

DO

NOT SMOKE while servicing batteries. Lead acid

off

batteries give can be ignited by flame, electrical arcing or by smoking.

Verify battery polarity before connecting battery cables. Connect negative cable last.

a highly explosive hydrogen gas which

Cooling System

Coolants under pressure have a higher boiling point than water. DO NOT open a radiator pressure cap when coolant temperature is above engine is running.

Keep the Unit and Surrounding Area Clean

Make sure that oily rags are not left on or near the engine. Remove all unnecessary grease and oil from the unit.

Accumulated grease and oil can cause overheating and subsequent engine damage and present a potential fire hazard.

212F

(100°C)

or while

E-6

Table' of Contents

TITLE

General Information Speclflcations.. Dimensions and Clearances Assembly Torques and Special Tools Engine Troubleshooting Oil System Fuel System Ignition and Battery Charging.. Starting System Engine Disassembly

PAGE

. l-1

.2-1

.3-1

.4-1

.5-1

.6-1

.7-1

.8-1

.9-1

.10-1

WARNING]

EXHAUST GAS

Exhaust gases from all fuels (including diesel, gasoline, liquid propane, natural gas) contain carbon monoxide, an odorless and colorless gas. Carbon monoxide is poisonous and can cause unconsciousness and death. Symptoms of carbon monoxide poisoning can include:

IS

DEADLY!

Dizziness Nausea Headache

Weakness and Sleepiness

IF

YOU

OR ANYONE ELSE EXPERIENCE INTO THE FRESH AIR IMMEDIATELY. .If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired.

Protection against carbon monoxide inhalation includes proper installation,

ventilation and regular, frequent visual and audible inspections

exhaust system.

Throbbing in Temples Muscular Twitching Vomiting Inability to Think Coherently

ANY

OF

THESE SYMPTOMS, GET OUT

iii

of

the complete

General Information

INTRODUCTION

This manual deals with specific mechanical and electrical information needed by engine mechanics for troubleshooting, servicing, repairing, or overhauling the engine.

Use the table of contents for a quick reference to the separate engine system sections.

Use the separate Parts Catalogs available at the dealer level, for parts identification and for establish-

ing their proper location on assemblies.

The troubleshooting guide is provided as a quick

reference for locating and correcting engine trouble.

The illustrations and procedures presented in each section apply to the engines listed on the cover. The flywheel-blower end of the engine is the front end right and left sides are determined by viewing the engine from the front.

The disassembly section contains major overhaul

procedures for step by step removal, disassembly, inspection, repair and assembly of the engine

components.

If a major repair or an overhaul is necessary, a competent mechanic should either do the job or supervise and check the work of the mechanic assigned to do the job to ensure that all dimensions, clearances and torque values are within the specified tolerances.

The wiring diagram on the last page of the manual shows how the electrical components are interconnected.

A parts catalog (availableat the dealer level) contains detailed exploded views of each assembly and the

individual piece part numbers and their proper names for ordering replacement parts.

so

Use only Genuine Onan replacement parts to ensure quality and the best possible repair and overhaul results. When ordering parts, always use the complete Model and Spec number as well as the Serial number shown on the nameplate.

ENGINE MODEL REFERENCE

Identify your model by referring to the MODEL and SPEC (specification) NO. as shown on the unit name

plate

serial number when making reference to your engine. How to interpret MODEL and SPEC

1.

Factory code for general identification of basic engine series.

2.

Number of cylinders.

3.

Cubic inch displacement.

4.

Engine duty cycle.

5.

Fuel required (G=gasoline).

6.

Cooling system description

(A=air-cooling-pressure).

7.

BHP rating.

8.

Factory code for designated optional equipment, if

any.

9.

Specification (spec letter) which advances with factory production modifications.

Always use this number and the engine

NO

2 60G G

1234567

A

024

1

8 9

A

WARNING

INCORRECT SERVICE PERSONAL INJURY AND/OR EQUIPMENT DAMAGE. SERVICE PERSONNEL MUST BE QUALIFIED TO PERFORM ELECTRICAL AND/OR MECHANICAL SERVICE.

OR

REPLACEMENT OF PARTS CAN RESULT IN SEVERE

1-1

I

Specifications

This manual contains

SPECIFICATION

Number of Cylinders Bore

Stroke

Displacement

Compression Ratio Rated Speed (Maximum) RPM Power at BHP

Rated Speed Oil Filter Oil Capacity Without Qt

Filter (litre) Oil Capacity With Qt

Filter Change (litre) Crankshaft Rotation

(viewed from flywheel) Clockwise Governor Variable Speed Mechanical

Valve Clearance (Cold)

Intake in

Exhaust in

Spark Plug Gap in

Breaker Point Gap Static (Spec A-E)

(Full

Separation and Engine Cold) (mm) Ignition Timing Cylinder Compression psi

SI

metric equivalents that

after the

U.S.

customary units

UNIT

MEASURE

follow

immediately in parentheses

of

measure.

OF

in

(mm)

in

(mm)

cu

in

(cm3)

SERIES

T-260G

3.56

(90.48)

3.0

(76)

60

(983)

7.0 3600

24

(kw)

(1 7.9)

Full

2.5

(2.4)

3.0

(2.8)

.005

(mm)

(0.1 3)

.013

(mm)

(0.33)

.025

(mm)

in

BTC

(0.64)

.020

(0.51)

20°

75

(kPa)__

51 7

2

to

Flow

to

115

to

1

793

2-1

Dimensions

All

clearances given at room temperature

parentheses) unless otherwise specified

DESCRIPTION MINIMUM MAXIMUM CYLINDER

Cylinder Bore Honed Diameter

Maximum Allowable

Taper 0.003 (0.08)

Out-of-Round Main Bearing Inside Diameter (Without bearing) 2.1 87 Main Bearing Inside Diameter (Installed) Camshaft Bearing Bore (Bearing Installed) Interference Stud Height from Top Surface of Block

Spec C, D, E

Top2 2.00 (50.80) (2.06 (52.32)

Middle 4 1.84 (46.74) 1.90 (48.26)

Bottom 4 1.16 (29.46) 1.22 (30.99)

CRANKSHAFT

Main Bearing Journal Diameter 1.9992 (50.78) Main Bearing Clearance

Spec A-E

Begin Spec F Connecting Rod Journal Diameter Crankshaft End Play

CONNECTING

Large Bore Diameter (Without bearing installed

and rod bolts properly torqued Connecting Rod Side Clearance Piston Pin Bushing Bore (Without bearing) Piston Pin Bushing Bore with Bearing,

(Finished bore) Bearing

Aluminum Rod

Iron Rod

CAMSHAFT

Bearing Journal Diameter

Bearing Clearance

End Play

Spec A-E

Begin Spec F Camshaft Lift

Intake

Begin Spec Begin Spec E Begin SpecF 0.305 (7.75)

Exhaust

Begin Spec Begin Spec E Begin SpecF 0.295 (7.49)

BLOCK

ROD

to

Crankshaft Clearance

A

and

of

70°F

(21

Clearances

C)

All

dimensions in inches (approximate miilimetre dimensions in

Inches

3.5625 (90.49) 3.5635 (90.51)

2.0015 (50.84) 2.0040 (50.90)

1.3760 (34.95) 1.3770 (34.98)

0.0025 (0.064) 0.0038 (0.097)

0.0024 (0.061) 0.0042 (0.107)

1.6252 (41.28) 1.6260 (41.30)

0.005

1.7505 (44.46) 1.7510 (44.48)

0.0020 (0.051) 0.0160 (0.406)

0.8115 (20.61) 0.8125 (20.64)

0.7504 (19.06) 0.7508 (19.07)

0.0020 (0.051) 0.0033 (0.084)

1.3740 (34.90) 1.3745 (34.91)

0.0015

0.0030 (0.076) 0.0120 (0.305)

0.011 (0.28) 0.048 (1.22)

0.286 (7.26) 0.294 (7.47)

0.285 (7.24) 0.293 (7.44)

0.291 (7.39) 0.299 (7.59)

0.283 (7.19) 0.291 (7.39)

(mm)

(55.55)

(0.13)

(0.038) 0.0030 (0.076)

Inches (mm)

0.003 (0.08)

(2.188 (55.58)

2.0000

0.009 (0.23)

(50.80)

DESCRIPTION

PISTON

Clearance in Cylinder

Measure Piston Pin Bore.. Ring Groove Width

Top

No.

PISTON PIN

Clearance in Piston Clearance in Connecting

Aluminum Rod Iron Rod

Diameter.

-PISTON RINGS

Clearance

Top Groove Ring End Gap in Cylinder

INTAKE VALVE

Stem Diameter Clearance (Stem to Guide)

Valve Face Angle

tNTAKE VALVE SEAT

Seat Cylinder Head Bore Diameter.. Seat Outside Diameter Valve Seat Width Valve Seat Angle

EXHAUST VALVE

Stem Diameter Clearance (Stem to Guide) Valve Face Angle

EXHAUST VALVE SEAT

Seat Cylinder Head Bore Diameter..

Seat Outside Diameter Valve Seat Width Valve Seat Angle

VALVE GUIDE

Inside

TAPPET

Body Diameter

Bore Diameter..

Clearancein Bore

VALVE SPRINGS INTAKE AND EXHAUST

Valve Spring Free Length (Approx.) Valve Spring Length

Valve Open..

Valve Closed Spring Load Spring Load

1.187

Below Top of Piston and

. . . . . . . . . . . . . .

1

Compression Ring

2

Compression Ring..

3

Oil Control Ring

. . .

.

. .

. . . . . . . . . . . . .

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. ‘ .

. . . . .

Diameter

. . . . . . . . . .

.

. .

. . . . . . .

.

. . . . . . .

@

1.375

inch (Valve Closed).

@

1.125

inch (Valve Open)

90"

.

. . . .

. . . . .

.

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.

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Rod

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. . . . . . . . . . . . . . . . . . . . . . . .

from pin

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Inches

0.0070

0.7502

.

0.080

0.188

0.0001 (0.003)

0.0002

.

0.7500

0.002

0.010

.

0.3425

0.0010

.

1.5645

1.5690

0.031

. .

0.3410

0.0025

1.2510

1.2550

.

0.031

.

0.344

0.7475

0.7500

0.0015

38

71

MINIMUM

(mm)

(19.055)

Ib.

Ib

(17 (32

MAXIMUM

Inches

kg) kg)

0.0090

0.7506

0.081

0.189

0.0005

0.0008

0.7502

0.008

0.020

440

1.5655

1.5700

0.047

45O

0.040

440

1.2520

.1.2560

0.047

45O

0.7480

0.7515

0.003

(28.58) (34.93)

42

79

(0.1 78)

(2.032) (2.032) (4.775)

(0.005)

(1

9.05)

(0.051) (0.254)

(8.70) 0.3430

(0.025) 0.0025

(39.74) (39.85) (0.787)

(8.661) 0.3420 (0.064)

(31.78) (31.88) (0.787)

(8.74) 0.346

(1

8.99)

(1

9.05)

(0.038)

1.662 (42.21)

1.125

1.375

(0.229)

(19.065)

(2.057) (2.057) (4.801)

(0.01 3)

(0.020)

(19.06)

(0.203) (0.508)

(0.064)

(39.76) (39.88) (1.194)

(8.687) (0.1 01)

(31.80)

(31.90)

(1.194)

(1

(1 9.09) (0.076)

Ib.

Ib

(mm)

(8.71)

(8.79)

9.00)

3-2

DESCRIPTION

GEAR BACKLASH Timing Gear

Spec

A-E

Begin Spec

F

Oil Pump Gear

spec

A-E

Begin Spec

F

GOVERNOR

Dashpot to Governor Arm Bracket..

MINIMUM

Inches

0.002

0.001

0.002

0.001

0.040

(mm)

(0.051) (0.025)

(0.051) '(0.025)

(1.02)

MAXIMUM

Inches

0.003

0.005

0.008

0.060

(mm)

(0.076) (0.127)

(0.127) (0.203)

(1.52)

3- 3

Assembly

The torque values given in Table 1 have been deter- Check all studs, nuts, and capscrews, and tighten as

mined for the specific applications. Standard torque required to keep them from working loose. Refer to the values must not be used where those listed in Table apply. The engine assembly torques given here will capscrews. assure proper tightness without danger threads.

new engine oil before torquing.

All

threads must be clean and lubricated with

Torques

1

of

stripping

PARTS MANUAL

for the location

of

washers and

DESCRIPTION

Cylinder Head Nuts (with

Compression Washers)

SpecA-E Begin Spec F

Cylinder Head Nuts (without

Compression Washers)

SpecA-E

Begin Spec F

Rear Bearing Plate

Connecting Rod Bolt

SpecA-E

Begin Spec F

Flywheel Capscrew.

Starting Mounting Bracket

to Oil Base Screws.

TABLE

TORQUE

SPECIFICATION DESCRIPTION

F1.-Lb. Nm

11-13 (15-18) Intake Manifold Mounting

14

14-16 (19-22) Screws

17

25-28 (34-38) Begin Spec F 14-16 (1 9-22)

27-29 (37-39) 50-55 (67-75)

24-26 (33-35) Nuts.

(19) Screws

(23) Spec

1.

Gear Case Cover. Oil Pump.

Valve Cover.

Exhaust Manifold Mounting

A-E

Other 1/4” /4" Cylinder Block Studs

and Nuts

Other 5/16" Cylinder Block

Studs and Nuts

Other 3/8” Cylinder Block

TORQUE

SPECIFICATION

F1.-Lb. Nm

8-10 (1 1-14)

7-9 (10-1 2)

4-8

20-23

9-11

7-9 (10-72)

8-10 (1 1-13)

18-23 (24-31)

(27-31)

(

5-11)

(27-31) (12-15)

Special

The following special tools are available from Onan. For further information see

Tools

TOOL CATALOG

900-0019.

Valve Seat Driver Valve Guide Driver Oil Guide and Driver Combination Bearing Remover (Main and Cam) Combination Bearing Driver (Main and Cam) Flywheel Puller

4-1

Engine

Troubleshooting

I

IGNITION SYSTEM

FUEL SYSTEM

INTERNAL ENGINE

COOLING SYSTEM (AIR COOLED)

5-1

THROTTLE AND GOVERNOR

M-1686-1

Oil

System

CRANKCASE OIL

Refer to engine nameplate or Periodic Maintenance Schedule, located change interval. If operating in extremely dusty, high ambient, or low ambient conditions change oil more often.

Run engine until thoroughly warm before draining oil. Stop the engine, place a pan under the drain outlet and remove the oil drain plug or open the drain valve. After the oil is completely drained, replace the drain plug or close the drain valve. Refill with oil of the correct API classification and appropriate SAE viscosity grade for the temperature conditions.

Oil must meet or exceed the API designation SF, SF/CC or SF/CD. Refer to the chart to determine the proper

viscosity grade of oil to use. Straight weight oils are

recommended for severe duty use and at temperatures

above

32"

F (0°C) for minimum oil consumption.

in

the Operator's Manual, for oil

Oil

level should be to the engine and run for a short time to check for oil leaks around the drain plug.

FULL

mark of the dipstick. Start

WARNING

check oil while the engine is operating.

fingers and hands clear when removing the oil drain plug and wear protective clothing.

CAUTION

tures and

Crankcase pressure can blow out hot oil and cause serious burns.

Hot crankcase oil can cause burns if it is spilled or splashed on skin. Keep

ALWAYS REPLACE

FIGURE

may

1.

Do causes higher operating tempera-

cause foaming.

TIGHTLY

LEAKAGE MAY

CRANKCASE OIL

not overfill crankcase. Excess oil

OR

OCCUR

FILL

Do

OIL

NOT

LS-1170

I

FILTER

COOLING

FILTER

FINS

2.

OIL

FILTER

OIL FILTER CHANGE

Refer to engine nameplate or Periodic Maintenance

Schedule, located in the Operator's Manual, for oil filter change interval. If operating in extremely dusty, high ambient, or low ambient conditions change oil more often.

Spin

off

oil filter element and discard it. Thoroughly clean filter mounting surface and make sure new gasket is inserted in the element.

6-1

Apply a thin film of oil to the gasket. Spin element down by hand until gasket just touches mounting pad and then turn down an additional

1/2-3/4

turn.

Do

not

overtighten.

With oil in crankcase, start engine and check for leaks around filter element. Retighten only as much as necessary to eliminate leaks; do not overtighten.

Clean or replace crankcase breather baffle periodically. Be sure baffle material-doesn’t come apart and work into

the manifold.

To disassemble, remove breather hose from cap and valve assembly. Remove cap and valve assembly and wash in a suitable solvent. Replace cap and valve if balls do not move freely. Pull baffle out and wash in solvent.

To

allow free operation of the valve, screens must be

positioned as shown in Figure

3.

CRANKCASE BREATHER

The crankcase breather prevents pressure from

building up in the crankcase. It also prevents oil contamination by removing moisture or gasoline vapors and other harmful blow-by materials from the crankcase. Thesevapors are routed to the carburetor where they are mixed with incoming air and burned in the combustion chamber. cause leaks, high oil consumption, rough idle,

reduced engine power and a rapid formation of sludge and varnish within the engine.

Crankcase Breather Service

This engine uses. a crankcase breather valve for maintaining crankcase vacuum. If the crankcase becomes pressurized as evidenced by oil leaks at the seals, clean baffle and valve in a suitable solvent.

A

sticky breather valve can

PRESSURE LUBRICATION

All

engines use an oil pump to provide a constant flow of oil to the engine parts. The oil supply collects in the oil base where it is picked up by the oil pump pick-up

cup.

A

by-pass valve is used to control oil pressure. Drain oil before removing oil base and always use a new gasket when replacing the oil base.

Oil

Pump

The oil pump (Figure cover and is driven by the crankshaft gear. Inlet pipe and screen assembly are attached directly to the pump

body. A discharge passage in pump cover registers with a drilled passage in the crankcase. Parallel passages distribute oil to the front main bearing, rear main

bearing, and pressure control bypass valve.

4)

is mounted behind the gear

OIL

PUMP PICK-UP CUP

CAP AND VALVE

FIGURE

3.

BREATHER

HOSE

CRANKCASE BREATHER

HOSE

CLAMP

OIL PUMP ASSEMBLY

6-2

CRANKCASETURNED

ON LEFT SIDE

FIGURE

4.

OIL

PUMP

LS-1109

ASSEMBLY

Circumferential grooves in the main bearings supply oil to connecting rod bearings through drilled pas-

-.,sages from each main journal. \connects the front main bearing oil supply to

'camshaft bearing; rear cam bearing

ted. Oil overflow from the bypass valve provides lubrication to the camshaft drive gears.

Normal oil pressure should be higherwhen the engine is at normal operating temperature.

If

pressure drops below this value at governed

speed, inspect oil system for faulty components.

A

drilled passage

is

splash lubrica-

30

psi

(207

the

front

kPa) or

The valve is non-adjustable and normally does not need maintenance. Determine normally by inspecting plunger action as follows:

1.

Remove the behind gear cover and under governor arm.

2.

Remove spring and plunger with a magnet tool.

3.

Determine proper valve operation by checking the spring and plunger according to the following measurements.

3/8 x 24 x 7/8

if

valve is operating

cap screw located

Check oil pump thoroughly for worn parts. Oil pump

to prime it before reinstalling. Except for gaskets and

pick-up cup, component parts of the pump are not available individually. Install a new pump assembly any parts are worn.

Oil

By-Pass

The by-pass valve (located to the right and. behind gear cover, Figure excess oil to flow directly back to the crankcase.

Normally the valve begins to open about

(138

kPa).

Valve

5)

controls oil pressure by allowing

20

if

psi

Plunger Diameter..

Spring

Free Length.. Load

when compressed to

4.

Check the valve seat and clean away any accumulation of metal particles which could cause erratic

valve action. Verify that the valve seat is not damaged.

5.

Clean plungerand spring in parts cleaning solvent and install.

0.3105

1.00

2.6Ifr0.2

0.5

to

(7.89

inch

Ibs.

(11.6+0.9N)

inch

0.3125

to

7.94

(25.4

(12.7

mm)

mm) mm)

in.

FIGURE 5.

BY-PASS VALVE

6-3

Fuel

System

CARBURETOR

Set the adjustment screw about (rich) from the midpoint

of

this range. On Nikki

1/8

turn outward

The carburetor mixture screw settings were set for carburetors the idle adjustment is limited

maximum efficiency at the factory and should normally turn. Do not go beyond these limits. not be disturbed.

If

adjustments seem necessary, first be

sure the ignition system is working properly and

governor sensitivity is properly adjusted.

If

adjustment is needed, refer to Figures 1 and 2 and

proceed as follows:

CAUTION

and seat.

1.

Turn

Walbro mixture screw settings:

Forcing the mixture adjustment screw tight will damage the needle

in only until light tension can be felt.

THROTTLE

Turn both mixture screws in until lightly seated

l),

(Figure

then back the idle mixture screw out

turn and the main mixture screw out 1-3/4 turns.

Nikki

limited idle adjustment mixture screw

1/2

NlKKl

CARBURETOR

AND

LIMITED

IDLE

WITH

SEMI-AUTOMATIC

MIXTURE

SCREW.

CHOKE

settings:

The carburetor has a limited idle adjustment range

between stops be adjusted within these limits; in

1/8

turn. The screw should only

to

lean the

mixture, out to richen. There is no main mixture

adjustment.

MAIN FUEL

ADJUSTMENT

When replacing the idle mixture screw, turn in until

lightly seated, then back screw out Replace limiter cap

so

the tab is approximately

1-1/2

turns.

IDLE FUEL

ADJUSTMENT

centered.

2.

Start the engine and allow it

10

(at least

minutes).

to

warm up thoroughly

FIGURE

WALBRO

1.

CARBURETOR

CARBURETOR ADJUSTMENT

Some equipment manufacturers may require higher throttle stop speed and governor low speed rpm settings. Refer

to

equipment manufacturer’s Opera-

tor’s Manual for the correct rpm settings. When rpm

5.

Readjust the throttle screw for

1000

adjust the governor low speed screw for

idle.

rpm idle, then

settings are not specified by the equipment manufacturer use the rpm settings listed in Steps 3 and

5.

6.

Move the engine speed control to the fast position. Bend the high speed stop on the governor

3.

Move the engine speed control to the slow position. Back out the low speed screw on the governor

so

engine runs at the vehicle manufacturer’s recommended speed (Figure

2.)

the throttle stop screw on the carburetor controls engine speed (Figure screw for

4.

Determine the best idle mixture setting by first

1000

rpm idle.

turning the idle adjustment screw in until engine speed drops and then outward until engine speed drops again. Over a narrow range between these two settings, engine speed remains at its highest.

2).

Adjust the throttle stop

7.

Check the main mixture adjustment (Walbro carburetors only) by rapidly accelerating the engine from idle evenly and without hesitation. main adjustment screw out in

to

full speed. The engine should accelerate

If

it does not, turn the

1/8

turn increments until the engine accelerates smoothly, but do not turn it out more than

1/2

turn beyond the original

setting.

to

FS-1406-2

1100

so

1/8

FS-1002

rpm

the

7-1

HIGH

SPEED

THROTTLE

SCREW

STOP

In general, overhauling a carburetor consists of dis-

assembly,

a

thorough cleaning, and replacement

of

worn parts. Carburetor repair parts are available.

General instructions for overhauling a carburetor are given below. Carefully note the position of all parts while removing to assure correct placement when reassembling Read through all the instructions before beginning for a better understanding of the pro-

cedures involved. Carburetor components are shown

in Figure

3.

GOVERNOR

FRONT PULL GOVERNOR

THROTTLE

GOVERNOR

SPRING

SCREW

STOP

PLATE

CONTROL\

GOVERNOR

WARNING

explosion.

Ignition of fuel can cause serious

personal injury or death by fire or

Do

not permit any flame, cigarette, or other

igniter near the fuel system.

I

ARM

FS-1119

CHOKE

PLATE

NIKKI

CARBURETOR

FLOAT

ASSEMBLY

ADJUSTMENT

IDLE

FS-1440-3

STOP

ADJUSTMENT

SIDE

PULL

GOVERNOR

FIGURE

2.

GOVERNOR SPEED ADJUSTMENT

CARBURETOROVERHAUL

Carburetion problems that are not corrected by mixture adjustments are usually a result of gummedup fuel passages or worn internal parts. The most effective solution is a carburetor overhaul.

WALBRO CARBURETOR

FIGURE

3.

CARBURETOR ASSEMBLY

Removal Cleaning and Repair

1.

Remove air cleaner and hose.

2.

Disconnect governor and throttle linkage, choke control and fuel line from carburetor.

3.

Remove the four intake manifold cap screws and lift complete manifold assembly from engine.

4.

Remove carburetor from intake manifold.

Disassembly (Walbro)

1.

Remove throttle and choke plate retaining screws, then plates. Pull out throttle and choke shafts.

2.

Remove main jet and idle adjustment needle.

3.

Remove attaching screws and separate upper and lower carburetor sections.

4.

Carefully note position of float assembly parts, then pull out retaining pin and float assembly.

5.

Remove needle and unscrew needle valve seat.

Disassembly (Nikki limited idle adjustment)

1.

Remove main jet and idle adjustment needle.

2.

Remove attaching screws and separate upper and

lower carburetor sections.

3.

Carefully note position of float assembly parts, then pull out retaining pin and float assembly.

4.

Remove needle valve.

1.

Soak all metal components not replaced in carburetor cleaner.

Do

not soak non-metal floats or other non-metal parts. Follow the cleaning manufacturer’s recommendations.

2.

Clean all carbon from the carburetor bore, especially

where the throttle and choke plates seat. Be careful

not to plug the idle or main fuel ports.

3.

Dry out all passages with low pressure air

(35

PSI).

Avoid using wire or other objectsfor cleaning which

may increase the size of critical passages.

4.

Check the condition of the adjustment needle; replace

if

damaged. Replace float

if

loaded with fuel

or damaged.

5.

Check the choke and throttle shafts for excessive play in their bore. This condition may necessitate replacement

6.

Replace old components with new parts.

of

the carburetor.

BEND

TANG

TO

FLOAT

HERE

ADJUST

FLOAT LEVEL ADJUSTMENT

0.02

(0.51

.0512"

0.02

0.51

INCH

mm)

.028"

FUEL

LEVEL

0.25

INCH

(6.35

mm)

FUEL LEVEL

.472

(12.0

mm)

WITH FUEL

WALBRO

WITH FUEL

I

BEND

FLOAT

HERE

TO

ADJUST

CARBURETOR

ARM

MINIMUM

FLOAT

0.20

(5.08

MINIMUM

FLOAT

DROP

INCH

mm)

2913"

DROP

NO FUEL

BEND

HERE

NO FUEL

FLOAT

TO

ADJUST

FS-1524

ARM

FLOAT LEVEL ADJUSTMENT

FIGURE

NlKKl CARBURETOR

4.

CARBURETOR FLOAT LEVEL ADJUSTMENTS

7-3

FS-1683

Reassembly and Installation (Walbro)

1.

Install needle valve and seat, main jet and fioat assembly. Make sure that float pivot pin is properly placed and that float moves freely without binding.

2.

Gently push float tang down until needle

4).

(Figure

Measure float level; adjust

just

if

necessary.

Release float tang and measure float drop; adjust if necessary. When checking float level and drop, measure

3.

Position gasket on carburetor and attach carburetor

to

float body, not seam.

sections together with screws.

4.

Slide in throttle shaft and install plate using new screws. Before tightening the screws, the plate must be centered in the bore. To do

so,

back

throttle stop screw as necessary and completely

close the throttle lever. Seat the plate by tapping with a small screwdriver, then tighten screws. Install

the choke shaft and plate in the same manner.

5.

Install idle adjustment screw, throttle stop screw, and main fuel adjustment needle.

6.

Mount carburetor on intake manifold and install assembly on engine.

7.

Mount air cleaner assembly. Connect air intake hose, breather hose, fuel line, vacuum line, and

throttle linkage.

8.

Adjust carburetor and governor according

tions given in this section.

off

to

direc-

seats.

the

Reassembly and Installation (Nikki limited idle adjustment)

1.

Install needle valve, main jet, and float assembly. Make sure float pivot pin is properly placed and floa/ moves freely without binding.

2.

Turn carburetor on its side and measure float level

4).

(Figure

Adjust float level only

if

necessary.

Measure float drop (the distance from the top of

carburetor body

to

top of float). Adjust only

necessary.

3.

Position gasket on lower carburetor section and install upper carburetor section.

4.

Install idle adjustment screw, throttle stop screw,

and fixed main jet plug.

5.

Mount' carburetor on intake manifold and install

assembly on engine.

6.

Mount' air cleaner assembly. Connect air intake hose, breather hose, fuel line, vacuum line, and

throttle linkage.

7.

Adjust carburetor and governor according

to

direc-

tions given in this section.

if

?

VALVE DIAPHRAGM

ASSEMBLY

SCREWS

REED VALVE

FIGURE

5.

EXPLODED

PULSATING-DIAPHRAGM FUEL PUMP

Pulsating-diaphragm fuel pumps, or pulse pumps, rely on changes in crankcase vacuum to create a pulsating movement of the pump diaphragm. As the engine's pistons move outward, a vacuum is created. This vacuum is transmitted

to

pull back and suck fuel into the pump. As the

it engine's pistons move inward, crankcase vacuum is

reduced and the diaphragm return spring pushes the pump diaphragm forward, forcing fuel through the pump outlet.

to

the pump diaphragm, causing

PUMP BASE

\

VIEW

OF

FACET

FUEL

PUMP

Fuel Pump Test Procedure

Before testing make certain that fuel pump vacuum line connections are tight and free of leaks.

1.

Operate engine at an idle for five minutes that carburetor is full of fuel.

2.

Shut engine

off

and remove fuel inlet line from fuel

pump.

WARNING

Spilled fuel can ignite and cause serious personal injury or death.

Thoroughly clean-up any spilled fuel.

to

ensure

3.

Connect a vacuum gauge to fuel pump inlet using a piece of fuel hose with clamps.

4.

Start engine and allow to idle. for at least five seconds. Record vacuum gauge reading.

5.

Move throttle control least five seconds and record vacuum gauge reading.

6.

Shut engine

from fuel pump inlet. Connect fuel inlet line to fuel

pump.

i

!

7.

Remove fuel outlet line from fuel pump.

off

WARNING

Thoroughly clean-up any spilled fuel.

8.

Connect a pressure gauge to fuel pump outlet using a piece of fuel hose with clamps.

9.

Start engine and allow to idle for at least five seconds. While holding pressure gauge level with pump outlet, record pressure gauge reading.

10.

Move throttle control to high idle position and allow engine to run for at least five seconds. While holding pressure gauge level with pump outlet, record pressure gauge reading.

11.

Shut engine off and remove pressure gauge hose

from fuel pump outlet. Connect fuel outlet line

pump.

to

high idle position. Wait at

and remove vacuum gauge hose

Spilled fuel can ignite and cause serious personal injury or death.

to

fuel

Fuel Pump Repair

This section applies only to Facet fuel pump. The Nikki fuel pump is not repairable; replace unit are not within the values specified in TABLE

1.

Remove the vacuum and fuel lines. Inspect the lines for wear, cracking or brittleness. Replace as necessary.

2.

To' insure correct alignment when reassembling, scribe a line across the outer pump parts on each end of the pump.

3.

Holding the pump carefully, remove the assembly

screws (Figure

4.

Carefully pull apart the pump sections and check

for worn or damaged parts. Replace with new

parts where necessary or install pump repair

5.

Check and unclog ragm air bleed hole located behind the pump

diaphragm in the pump base.

CAUTION

and seal damage while inhibiting pump operation.

6.

Replace gaskets and reassemble pump. Reinstall assembly screws, checking the scribe marks for proper alignment. Reinstall fuel and vacuum lines and clamps.

WARNING

proper parts alignment or misconnected fuel lines

can result in leaking fuel, creating a serious fire hazard.

5).

if

necessary the small diaph-

A

clogged diaphragm air bleed

hole

ole can cause diaphragm wear

Use care when reassembling

and reinstalling the pump. Im-

if

test readings

1.

kit.

Repair or replace the fuel pump

within the values specified in TABLE

TABLE

if

test readings are not

1

PULSE PUMP TEST SPECIFICATIONS

Low

Idle

High Idle

2.6 inches

of mercury

2.6

inches

of

mercury

1.

Pump *outlet

Pressure

(Minimum)

1.7 psi

1.7

psi

AIR CLEANER

If air cleaner becomes too dirty,

engine will not receive sufficient air to run' properly. Symptoms: hard starting and overheating.

Engine is equipped with a paper element.

engine is equipped with polyurethane precleaner, it

must be removed, cleaned and oiled every25 hours of

operation, or more under extremely dusty conditions.

1.

To

clean precleaner, wash in water and detergent (Figure a sponge and allow to dry thoroughly. Distribute two tablespoons of SAE precleaner. Knead into and wring excess oil from precleaner.

6).

Remove excess water by squeezing like

Loss

of power, flooding,

If

30

engine oil evenly around the

the

7-5

SAFETY

COVER

POLYURETHANE

PRE-CLEANER

FS-1131

WASH

1.

SQUEEZE

2.

COAT

3.

4.

INSTALL

ELEMENT

WITH

OVER

DRY

OIL

PAPER

FIGURE

2.

Depending on conditions in which the engine is

7.

AIR

operating, the inner paper element should be replaced whenever it becomes excessively dirty or

oily.

CAUTION

Never run engine with air cleaner

removed. Dirt will enter engine

and wear

out

rings causing excessive blow-by.

DASHPOT ADJUSTMENT

On engines equipped with a dashpot, adjust as follows:

1.

Pull governor arm and linkage (away from carburetor) until throttle stop contacts throttle stop screw.

DASHPOT

ARM

BRACKET

CLEANER ASSEMBLY

2.

Holding throttle against throttle stop screw, adjust dashpot to obtain (Figure

3.

Secure dashpot to air cleaner support bracket with

hex nut.

CAUTION

necessary hold dashpot by hand when tightening hex nut.

8).

0.050

inch

(1.27

mm)

.-

Do

not grip dashpot with a pliers;

I

internal damage may occur. If

clearance

FIGURE

8.

DASHPOT CLEARANCE

7-6

STOP

THROTTLE TOP

SCREW

GOVERNOR ADJUSTMENT

THROTTLE

These engines are adapted for use where a wide range

SCREW

STOP

of speed settings is desired. Engine speed is controlled at any given point between minimum and maximum by

simply shifting the throttle lever on the dash panel until the desired speed is reached.

A

reliable instrument for checking engine speed is

required for accurate governor adjustment. Engine

t

speed can be checked with a tachometer.

HIGH

SPEED

CARBURETOR

THROTTLE

PLATE

Check the governor arm, linkage, throttle shaft, and lever for a binding condition or excessive slack and

A

wear at connecting points.

binding condition at any

point will cause the governor to act slowly and regula-

tion will be poor. Excessive looseness may cause a

hunting condition and regulation could be erratic.

Work the arm back and forth several times by hand while the engine is stopped to check for above conditions.

FRONT

PULL

If

the governor is hunting or not operating properly,

adjust as follows (Figure

1.

Disconnect linkage (A) from one of holes

2.

Push linkage (A) and governorarm

9).

(B)

as far back

(C).

(toward carburetor) as they will go. Holding linkage and governor arm toward direc-

3.

tion of carburetor, insert end whichever hole

(C)

in

governor arm lines up the

closest. If between two holes, insert

of

linkage into

in

next hole

THROTTLE

GOVERNOR

SCREW

THROTTLE

PLATE

out. Install clip to secure rod to arm.

side pull governor the governor spring is set by the

On

factory in the third hole of the governor arm. (Third~hole from pivot). On front pull governors the governor spring

GOVERNOR

SPRING

CONTROL

LINKAGE

GOVERNOR

is set by the factory in the second hole of the governor arm adapter. (Second hole from pivot.) sensitivity, move spring loop into a hole closer

To

increase

to

the pivot. To decrease sensitivity, move spring loop into a hole farther away from the pivot. After sensitivity has been

set

recheck the low speed rpm setting. Adjust

necessary.

if

PIVOT

GOVERNOR

SHAFT

YOKE

7.7

FIGURE

SIDE

PULL

GOVERNOR

9.

VARIABLE SPEED GOVERNOR ADJUSTMENTS

Ignition and Battery Charging

!

7.

BREAKER POINT IGNITION SYSTEM

This section applies to those engines equipped with an

automotive type battery ignition system. Both spark plugsfire simultaneously, thus the need for a distributor is eliminated. To maintain maximum engine efficiency, change the breaker points every 200 hours of operation.

Replace breaker box cover, coil wire, spark plugs,

and spark plug cables.

Continuity Test

As a check

for

proper ignition timing a continuity test

may be performed:

1.

Adjust breaker points

IGNITION TIMING

The timing is preset at the factory. Slight timing changes can be made by adjusting the point gap.

Breaker Point Replacement and Adjustment

1.

Remove spark plugs.

2.

Remove breaker box cover. Rotate crankshaft clockwise (facing flywheel) until points are fully open.

3.

Remove condenser (screw A) and detach condenser

B)

lead and coil lead (screw

4.

Remove two Allen screws

See Figure

(C)

and lift breaker

assembly from engine.

5.

Replace condenser and point assembly with new parts and reinstall using above procedure reverse order of removal.

6.

Adjust point gap by rotating crankshaft clockwise (facing flywheel) by hand until the points are fully open. Set the point gap (using flat feeler gauge) at

0.020

inch

(0.51

mm) by adjusting the socket head

screw

(D)

inward or outward (Figure

point gap is equivalent

to

20" BTC. Make sure feeler

gauge is clean and free of any grease, oil or

1.

1).

A0.020 inch

in

dirt.

2. Remove blower housing to expose timing marks on top of gearcase cover and flywheel (Figure 2).

FLYWHEEL

FIGURE

3.

Rotate flywheel clockwise until timing mark is

2.

TIMING

MARKS

aligned with the proper timing mark (Figure

located on top of gearcase cover. Refer to

FICATlONS

4.

Connect an ohmmeter or a continuity test lamp set

for proper number of timing degrees.

(TC)

TIMING

MARK

M-1397

SPECI-

2)

across the ignition breaker points. Touch one test

prod to the coil lead terminal (screw B, Figure

1).

FIGURE

1.

SETTING POINT GAP

5.

Touch the other test prod

to

a

good

ground on the

engine.

6.

Turn crankshaft against rotation (counterclockwise) until the points close. Then slowly turn the crankshaft with rotation (clockwise).

7.

The lamp should go out or continuity lost just as the points break which

is

where ignition occurs. timing is early (advanced) the point gap is too large.

too

If

timing is late (retarded) the point gap is

small. Adjust point gap accordingly.

If

ELECTRONIC

This section applies to those engines equipped with an electronic battery ignition system. Both spark plugs fire simultaneously, thus the need for a distributor is elimi-

nated. The electronic ignition module is located on the

engine gear cover behind the flywheel. The module

receives a timing signal from the magnets located within a trigger ring which rotates on the engine crankshaft (Figure functioning, proceed as follows:

3).

If

the electronic ignition is suspected of mal-

IGNITION

SYSTEM

Failure to ground spark tester

WARNING

result in ignition of cylinder gases and may cause,

severe personal injury.

2.

Pull spark plug wires spark plugs. Connect an approved spark tester to each of the spark plug wires and ground them away from spark plug hole. Turn key on and crank engine over for spark occurs regularly, the problem is not in the ignition system.

CAUTION

failure

3.

Connect a jumper lead directly from the positive

battery terminal to the positive coil terminal (smaller diameter of the two threaded posts). Crank engine over while watching for spark. occurs, the problem is in the low oil pressure cut out switch or related wiring, the lubricating system (low oil. pressure), or in the other circuitry bringing voltage

5

seconds while watching for spark.

of

the electronic ignition module.

to

the coil. If no spark occurs, go to step

away from spark plug hole may

off

spark plugs and remove

If

no spark occurs, go to step

Never putjumper lead to the coil negative terminal. This willcause

If

a

3.

spark

4.

I

IGNITION

MODULE

FIGURE

1.

Check all electrical connections to be sure they are clean and tight. wiring is intact, go to step

WARNING

plugs even when rotated by hand. Care should be taken to avoid an electrical shock.

WARNING

result in engine starting, which may cause severe personal injury.

3.

IGNITION MODULE AND TRIGGER RING

If

all connections are good and

2.

The electronic ignition will deliver

deliver full voltage to the spark

Failure to remove spark plugs before

before turning engine over may

ES-1670

4.

Refer

to

IGNITION

proper resistance. If coil checks out good, go to

step

5.

Connect positive side of voltmeter to negative coil terminal (larger diameter of the two threaded posts) and negative side of voltmeter to engine ground. Turn key on and rotate flywheel slowly by hand while observing voltmeter. Voltage should switch back and forth between battery voltage and

1-1.5.

If

voltage does not switch properly, replace

ignition module.

6.

Install spark plugs and wires. being replaced, be sure to connect red lead from new ignition module to positive (+)terminal of coil, black lead from module to negative terminal of coil.

CAUTION

failure

of

the electronic ignition module.

COIL

section to test coil for

If

ignition module is

B+

Never put negative terminal. This willcause

lead to the coil

8-2

The ignition timing is preset at the factory and is not

adjustable. For troubleshooting purposes, it to make an approximate check of the ignition timing by removing blower housing and using the gearcase timing marks.

is

possible

4. Rotate the flywheel slowly by hand in the clockwise direction until the voltmeter reading jumps from approximately 1 volt to battery voltage. At this point the flywheel timing mark should line up with the proper timing degree (see located on the gearcase timing marks. To recheck timing, the flywheel must be rotated another complete revolution in the clockwise direction. Moving the flywheel back and forth across the timing marks will not activate the electronic ignition control.

5.

Install spark plugs, wires, and blower housing.

SPEClFlCATlONS)

mark

FIGURE

Continuity

Test

4.

IGNITION TIMING

MARKS

FLYWHEEL

(TC)

MARK

M-1397

TIMING

BREAKER

POINT AND ELECTRONIC,

IGNITION COILS

To test primary and secondary windings within the

ignition coil first make sure the ignition power is

coil is at room temperature of 70°F (21 "C).

1. Use, a Simpson 260

2. Place a black lead on the negative coil terminal and a red lead on the positive coil terminal. Primary resistance should read between 3.87-4.73 ohms

for

breaker point coils, and between 2.90-3.60

for electronic ignition coils.

3. Change resistance setting on ohmmeter. Place ohmmeter leads inside on spark plug cable holes

(Figure between 12,600-15,400 ohms for breaker point ignition coils, and between 14,500-19,800 ohms for

electronic ignition coils.

4.

If

any of the above conditions are not met, replace

coil.

5).

VOM

or equivalent.

Secondary resistance should read

off

and

1. Pull spark plug wires off spark plugs and remove spark plugs and blower housing.

CAUTION

result in engine starting, which may cause severe

personal injury.

2. Turn ignition on.

3. Connect a voltmeter between the negative coil terminal (larger diameter of the two threaded posts) and a good engine ground.

WARNING

plugs even when rotated by hand. Care should be taken to avoid an electrical shock from the spark

plugs.

failure to remove spark plugs

before

before turning engine over may

The electronic ignition will

deliver full voltage to the spark

FIGURE

5.

COIL TEST

OHMMETER

SPARK PLUGS

Check and regap spark plugs every

6).

operation (Figure signs of fouling or electrode erosion.

FIGURE

Replace spark plugs that show

6.

SPARK PLUG GAP

100

hours of

BATTERY INSPECTION

Check battery cells with a hydrometer. (Figure specific gravity reading should be approximately 1.260 at

77OF

(25°C).

If

one or more cells are low on water, add distilled water

and recharge. Keep the battery case clean and dry. An accumulation of moisture will lead to a more rapid discharge and battery failure.

Keep the battery terminals clean and tight. Push the cable terminal down flush with or slightly below the top of the battery post (Figure coat the terminals with a light application of petroleum jelly or grease to retard corrosion.

8).

After making connections,

7).

The

BATTERY

Occasionally, it may be necessary to jump start(charge)

a

weak battery using a charged booster battery.

starting is necessary, the following procedure is recom

mended in order to prevent starter damage, battery

damage and personal injuries.

CAUTION

allowing may result if these guidelines are not followed.

1.

2.

3.

4.

5

minutes for starter

Disconnect engine load.

Use only a battery of the same voltage (12V) as is used with your engine.

Attach one end of the positive booster cable (red) to the positive terminal Attach the other end of the positive cable to the

positive terminal

attach one end of the negative

(black) to negative Attach other end of negative cable to a solid chassis ground on your engine.

WARNING

each other because it will short the battery causing hazardous arcing, which can cause severe personal injury.

Jump starting in any other manner may result in

5.

damage to the battery or the electrical system.

JUMP

Do

not engage starter for periods

Ionger

of

(-)

Do

negative cable ends

STARTING

than

30

seconds without

to

cool. Starter failure

of

the booster battery.

your engine battery.

(-)

booster cable

terminal of booster battery.

not allow the positive and

to

If

jump

touch

Poor contact at the battery cable connections is often a source of trouble. Make sure battery cables are in good condition and that contacting surfaces are clean and tightly connected. Do not reverse battery leads. Use

recommended battery tools when disconnecting leads to avoid mechanical battery damage.

Ignition of explosive battery gases can cause severe personal injury.

not smoke while servicing batteries.

SPECIFIC

GRAVITY READING

SHOULD BE

at

77'F

1.260

FIGURE

7.

SPECIFIC GRAVITY TEST

(25°C)

Do

ON

Turn ignition switch to

6.

Never jump start a frozen battery.

WARNING

explode. Never expose the battery or an electrical spark because a battery generates highly explosive hydrogen gas.

FIGURE

to

o

8.

BATTERY CABLE CONNECTION

to start engine.

do

so

can cause the battery

to

BATTERY POST

CABLETERMINAL

an open flame

to

8-4

FLYWHEEL ALTERNATOR

This unit is equipped with a permanent magnet flywheel

alternator and solid-state voltage regulator-rectifier

,output control). See Figure electrical units, precautions are necessary when servicing. Observe the following:

CAUTION

connected

running. Do not reverse battery cables.

Weak ignition spark or a discharged battery indicates trouble in the charging system. But before testing the engine’s charging system, always check the battery for serviceability.

Keep these points in mind when testing or servicing the flywheel alternator:

1.

Be sure engine is being run long enough and fast enough to recharge battery after each start. Charging system tests require a full charged battery. Alternator

output is reduced in direct proportion to engine rpm. Also, power required for accessories reduces power available to recharge battery.

This engine uses a

-

ground system. Alternator must be

to

battery at all times when engine is

9.

As with all solid-state

12

volt, negative

The regulator-rectifier has built in protection against

2.

open circuits or short circuits on the alternator output (B+) terminal. Either condition will cause the regulator-rectifier to shut off and appear as

functioning Prior to checking the regulator-rectifier,

check all wiring between the regulator-rectifier B+

terminal and the battery positive terminal to

assure it is free of open circuits, resistances or short circuits. Also, it may have insufficient power to “turn on” the regulator-rectifier.

Be sure regulator-rectifier plug (connector) is

3.

inserted properly. Plug must bottom in receptacle; this eliminates any resistance due to a poor connection. Keep clean and tight.

Make sure alternator stator leads are not shorted

4.

together.

Be sure regulator-rectifier has a good ground

5.

connection. Mating surface for mounting must be clean and fasteners tightened properly.

Never reverse the battery leads.

6.

if

the battery is extremely discharged

if

it is not

FLYWHEEL

VOLTAGE REGULATOR

CONNECTIONS

.___-_-

FIGURE

B+ STARTER IGNITION)

ES-1333

9.

FLYWHEEL ALTERNATOR SYSTEM

MOUNTED BEHIND

BLOWER WHEEL

TO

BATTERY

MOUNTED ON

CYLINDER COVER

--

REGULATOR MUST BE GROUNDED

THROUGH MOUNTING BOLTS

CAUTION:

ES-1332

With the engine running between observe the panel ammeter (if not already equipped, rectifier case. connect a test ammeter).

proceed with the Alternator Output Test.

If

ALTERNATOR OUTPUT TEST

Use a volt-ohmmeter such as the Simpson 270, when

testing the charging system.

1. With the engine running, check the battery terminal voltage (regulator output) using a DC voltmeter.

Voltage output should be within the values specified

in Table 1. replace regulator-rectifier assembly. less than specified, proceed to step 2.

2. Examine all wires for loose, corroded, broken connections, short circuits, etc. Check fuses. Repair

as needed

rectifier B+ terminal to battery positive terminal

If

voltage

to

assure complete

is

1800

to 2600 rpm, and from battery negative terminal to regulator-

no charging is evident, engine running, proceed to step

3.

Disconnect plug from regulator-rectifier and test

the AC voltage at the plug with engine running near

greater than specified

If

voltage is

circuits

from

regulator-

3600 rpm. specified in Table is as specified but DC voltage is low, replace

regulator-rectifier.

4. Use the opens in the stator (unit not running Disconnect plug from regulator'-rectifier. Connect ohmmeter

test leads to wires coming from stator. Refer to Table

not as specified, replace stator. readings are as specified and windings are not

shorted

loss

must be replaced Check for magnetism with steel

tool blade. Next, connect one ohmmeter test lead to stator wire, connect the other test lead the ohmmeter reading is low the stator is grounded and must be replaced.

If

Rxl

1

for resistance specifications.

to

ground, low AC voltage may be due to

of magnetism

If

battery voltage remains low with

3.

AC voltage reads more or less than

1,

proceed to step 4.

scale on the ohmmeter for detecting

If

so,

blower wheel assembly

If

AC voltage

If

resistance is

If

stator resistance

to

ground.

If

TABLE

1.

TESTING

15-

AND 20-AMPERE

PROCEDURE-.

I

1.

Battery Battery Voltage unit not running.

2. Regulator Battery Voltage after unit is running 3

to 5 minutes.

3. Alternator Stator

and Wiring

4. Alternator and Wiring

Ohmmeter reading from stator

output unit not running. Check at plug.

Measure AC open circuit stator voltage

with unit running. Measure between two stator leads with plug disconnected and unit running at approximately 3600 rpm.

SYSTEMS

12 VDC

13.6 to 14.7 VDC

0.1 to 0.2 Ohms

40 VAC minimum

60

VAC maximum

12 VDC

13.6 to 14.7 VDC

0.3 to

0.5

Ohms

31 VAC minimum 51 VAC maximum

8-7

ENGINE WIRING DIAGRAM

(Solenoid

8-8

Shift

Type

Starter)

Starting

System

ELECTRIC STARTER

Normally the starter will require little or no service other

than possible brush replacement. However,

accident or misuse, the starter requires service or overhaul, the following information will provide the information necessary to perform this service.

Service

When starting engine, note starter motor action. The pinion gear should mesh quickly with flywheel ring gear and spin engine. Once engine starts and solenoid opens, the starter should disengage and stop. cranks engine slow, or not at all, check start circuit components. Failure to crank is normally caused by low battery charge, defective battery cables, corroded or poor connections, or low temperatures. these variables, startercontinues to crank slowly, starter

must be removed and repaired.

Starter Removal

WARNING

death. Disconnect the battery cables when repairs are made to the engine, controls, or housings.

1.

Remove both battery cables from battery. Disconnect ground cable first.

Accidental starting of the engine can

cause severe personal injury of

if

through

If

starter

If

after checking

2.

Disconnect battery cable and electrical lead wires

from starter.

3.

Remove blower housing and cylinder air housing.

4.

Remove flywheel and starter motor.

Starter Disassembly (Inertia Type)

Remove through-bolts and separate end cap,

housing, and armature (Figure

2.

Disassemble drive assembly and drive end cap by loosening the self-locking stop nut.

3.

Inspect starter for damaged or worn parts.

4.

Repair or replace all damaged or worn parts, as needed.

1).

Starter Assembly (Inertia Type)

1.

Before reassembling the starter, wipe from parts with a clean cloth or blow compressed air.

Do not immerse bearings in

CAUTION

ped in clean engine oil for dirt removal.

cleaning fluid. Use a brush dip-

off

with filtered,

any dirt

THROUGH BOLT

\

I

STOP

NUT

END

CAP

PINION GEAR

FIGURE

SEAL

I

BRUSHES

\

-__-

INPUT STUD

NUT

1.

STARTER MOTOR (INERTIA TYPE)

9-1

ARMATURE

BRUSH

\

SCREWS

ES-1334

2. Assemble brushes

so

that the chamfered side is

Starter Disassembty

(Solenoid

Shift

Type)

away from the brush springs. Make sure brush wires do not rub against the commutaor or end cap.

1.

Remove “M” terminal nut and wire lead from

3. Torque brush screws to a value of 3 to 3.5 ft-lbs

5

Nm).

(4

to

solenoid (Figure 2).

2. Remove the two solenoid mounting screws and

4.

Torque input stud nut to a value of 7 Nm).

5.

Apply a thin film of grease to the commutator end of 3. Scribe a mark across frame and rear bracket to aid

4

to 5 ft-lbs

(5

to

remove solenoid.

the armature shaft and to the portion of the shaft that in assembly. Remove the two through bolts. contacts the bearings. Apply a generous film of silicone base grease shaft threads.

6.

Torque stop nut to a value of 20 to 25 ft-lbs (27 to

34

Nm).

7.

Torque through bolts to a value

8

Nm).

(GE

Versilube 322-L) to the

Of

4.5

to 6 ft-lbs

(6

to

4.

Remove rear bracket and frame assembly.

5.

Carefully remove armature and lever from front bracket. Note direction of lever and retainer.

6.

Remove the two brush mounting screws, and remove the rear bracket.

8.

Apply a small amount of

(GE

Versilube 322-L) to armature shaft spline.

a

silicone based grease

7. Remove brush holder assembly from the frame by

9.

Install dust cap, pinion gear, dust cover spacer, pulling the brushes out.

anti-drift spring, stop nut washer, and stop nut.

10.

Push dust cover

BUSHING

on

FRONT

BRACKET

until it snaps into position.

SOLENOID

THRUST

BRUSH

HOLDER

ASSEMBLY

THROUGH

FIGURE

2.

STARTER MOTOR

(SOLENOID

SHIFT

TYPE)

8.

Push stopper toward pinion and remove snap ring (Figure

3).

Remove stopper and overrunning clutch from armature shaft.

SNAP

\

STOPPER

RING

ES-1194

FIGURE

10.

Inspect starter for damaged or worn parts.

1.

Repair or replace all damaged

3.

REMOVING OVERRUNNING CLUTCH

or

worn parts, as

needed.

Starter

1.

Assembly (Solenoid

Shift

Type)

Install seal in nose housing. Install overrunning clutch on the armature shaft.

2.

Slide stopper on the armature shaft. Position snap ring in groove in armature shaft.

3.

Pull stopper all the way over snap ring (Figure may be necessary to tap snap ring into groove with a punch while maintaining tension on stopper.

Es-1622

4).

It

FIGURE

4.

Lubrication: When starter motor is assembled apply

4.

INSTALLING STOPPER

grease to each of the following points (Recommended grade: Multemp PS

No.

2):

Armature shaft spline

Both bushings (Both ends of armature) Stopper on armature shaft Pinion gear

'Sliding portion of lever

5.

Fit overrunning clutch into lever, and install with

armature in the front bracket.

6.

Install lever retainer and spacer. Position frame assembly over armature on the front bracket.

7.

Install brush holder assembly. Position brushes in brush holder. Make certain positive lead wires are not grounded.

8.

Install washers, as required, on the rear end of armature shaft to obtain an armature shaft thrust gap of

0.05

to

0.5

mm

(0.002

to

0.02

inch). New

washers are required if rear bracket is replaced.

9-3

Table

1.

Starter Assembly Torques

9.

Install rear bracket. Secure brush holder to rear bracket with two machine screws.

10.

Install and tighten the two through capscrews.

11.

Install soienoid plunger in lever. Secure solenoid to

front bracket with two machine screws.

“M”

to

0.080

on solenoid.

inch

Install wire lead to the terminal

12.

13.

After assembly, adjust pinion clearance. Pinion clearance should be

2.0

mm);

if

not, check as follows. See Figure

A.

Connect starter

Figure

5.

Close switch. This will shift pinion into

0.020

to

a battery, as shown in

cranking position. Push pinion back

B.

clearance.

specified limits, adjust by adding

by

hand and measure pinion

If

clearance does not fall within the

or

removing

shims located between solenoid and front

bracket. Adding shims decreases clearance; removing shims increases clearance. Shims are included with replacement solenoid.

(0.5

5.

to

ES-1001

FIGURE

Inspecting tor an Open Circuit in Armature:

6.

TESTING ARMATURE FOR GROUNDS

Using an ohmmeter, check for continuity between the commutator segments.

If

there is no continuity (high resistance), the

segments are open and armature must be replaced.

PINION

STOP

RING

FRONT

BRACKET

J

FIGURE

Inspection and Testing

Inspect the starter components for mechanical defects before testing for grounds or shorts.

5.

PINION CLEARANCE ADJUSTMENT

Testing Armature tor

a

Short

Circuit:

Use a growler for locating shorts in the armature. Place armature in growler and hold a thin steel blade (e.g. hacksaw blade) parallel to the core and just above armature in growler (Figure cause the blade

to

vibrate and be attracted to the core.

it

while slowly rotating

7). A shorted armature wi

It

armature is shorted, replace with a new one.

HACK

SAW

Testing Armature

tor

Grounds:

Touch

armature shaft or core and the end of each commutator bar with a pair of ohmmeter leads (Figure

6).

A

low ohmmeter reading indicates a grounded armature. Replace grounded armature.

9-4

FIGURE

7.

TESTING ARMATURE FOR SHORT CIRCUITS

ES-1002

Commutator Inspection:

discolored, clean with number

If

commutator is dirty or

00

to

000

commutator

paper. Blow grit out of armature after cleaning.

commutator is scored, rough, or worn, turn it down in a

lathe.

Inertia type starter inspection

Housing Inspection:

Permanent magnets are glued to inside of the housing. Magnets must be secure and free of cracks.

Brush Inspection:

1/4

inch

(6.35

If

brushes are worn shorter than

mm), replace them. Check to see that brushes move smoothly in the brush holders. See Figure

8.

0.25

inch

Check for shorts between positive side of brush holder and brush holder base.

If

there

is

continuity, replace

holder assembly. Check for free movement of brushes.

All

brushes should move freely in the brush holders.

Overrunning Clutch:

wear

or

damage.

If

pinion gear is worn or damaged, inspect flywheel ring

gear also. Rotate pinion.

Inspect pinion and spline teeth for

It

should turn free when turned in one direction, and lock when turned in the opposite direction.

Do

not clean overrunning clutch in in

or

solvent

Washing the clutch will cause the grease

Solenoid:

Push solenoid plunger in and release

liquid cleaning solution.

to

leak out.

it.

The plunger should return to its original position. While holding plunger all the way in, check for continuity between terminals “M” and “B”. If there is no continuity, replace the solenoid (Figure

10).

After replacing solenoid

check pinion clearance.

Pinion Gear:

FIGURE

If

8.

BRUSH

WEAR

LIMIT

pinion gear is badly worn, has broken teeth, or pinion splined sleeve is damaged replace pinion gear and dust cover assembly.

If

pinion gear is in good condition, wipe armature shaft spline and pinion clean.

Solenoid

Field Coil:

between brushes.

shift

type starter inspection

Use an ohmmeter to check for continuity

If

there is no continuity, the field coil is open and must be replaced. With field coil mounted in the frame, check for continuity between the field coil and frame. Replace frame assembly

Brushes: Clean around brushes and holders, wiping

if

there is continuity.

off

all brush dust and dirt. If brushes are worn shorter than

11.5

mm

(.4528

inch) replace them (Figure

11.5mm

(.4528

inch)

9).

+

/-

WEAR

LIMIT

ES-1193

FIGURE

9.

BRUSH WEAR LIMIT

Bushings:

TERMINAL

FIGURE

If

either the front or rear bushing show signs

10.

SOLENOID TERMINALS

“B”

ES-1345

of wear or damage, replace them. Bushing and rear

bracket are replaced as an assembly. Check armature

shaft thrust gap

if

rear bracket is replaced.

Remove front bushing by tapping bushing from inside

a

7/16

with

inch tap.

Do

not remove cap from front bracket. Thread capscrew, same size as tap, into bushing. Using a slide hammer remove bushing from front bracket, Press new bushing into front bracket. Use care not to distort inside diameter of bushing.

9-5

Brush Replacement:

at the brush.

Be

1/4 to 3/8 inch (6.5 to

Cut old positive brush from pigtail

careful not to damage field coil. Clean

9.5

mm) of brush end of pigtail

with sandpaper or emery cloth (Figure

PIGTAIL

STILL ATTACHED

TO FIELD COIL

SMALL CHAMFER

(approx.

EXTEND BEYOND

BRUSH

LARGE

CHAMFER

REPLACEMENT

BRUSH

11).

CLEAN

1/4

MUST SURFACE

to

NOT

3/8

inch)

STARTER MOTOR

PINION GEAR

FLYWHEEL

STARTER GEAR FREE TRAVEL WHEN

RING

GEAR

0.020

0.015

inch

(0.51

0.38

mm)

ENGAGED WITH FLYWHEEL GEAR

ES-1003

FIGURE

11.

BRUSH REPLACEMENT

Push prepared end of pigtail lead into hole in replacement brush from the small chamfered side. Solder pigtail lead to replacement brush on the large chamfered side, using

50/50

tin/lead, rosin core solder and a standard 240/325 Watt soldering iron. Use a file to remove any excess solder that may extend beyond brush surface.

CAUTION

Pigtail lead must not protrude from surface on the soldered side of brush.

Toprevent stiffening of pigtaillead to not use excessive

amount of solder and heat.

Starter Mounting

Before installing starter motor, make sure the starter mounting surface on the engine base is clean and free of oil.

To install starter on T-260G (Spec A) engines use the following procedure. On these engines starter pinion gear lash requires adjustment and must be checked when starter is installed.

Install starter motor and tighten mounting capscrews

just enough to hold starter in place.

Remove spark plugs from the engine.

This

allows

free movement of the flywheel.

FIGURE

To adjust lash on starters without slotted mounting

5.

12.

CHECKING

STARTER

GEAR

LASH

holes, remove starter. Use a 21/64 inch (8.334 mm) drill to enlarge one mounting hole in starter mounting bracket.

Install starter motor and adjust lash to 0.020 in.

6.

0.015

in:

(0.51

mm 0.38 mm).

Remove flywheel and torque starter mounting

7.

capscrews to 24 to 26 ft-lbs (33 to 35 Nm). Use Onan flangehead capscrews or SAE grade

Do

with a hardened flatwasher.

not use lockwashers.

8

capscrews

Failure to torque starter bolts

CAUTION

properly may cause starter failure

and ring gear damage.

8.

Install flywheel spark plugs, blower housing, and cylinder air housings. For correct cylinder air housing installation (required on some models), refer to Cylinder Air Housing Clearance.

Connect battery cable and wires to starter. Connect

9. battery cables to battery. Connect ground cable last.

To

install starter on T-260G (Beginning Spec B) engines use the following procedure. On these engines starter pinion gear lash does not require adjustment.

Manually pull the starter pinion gear outward on its shaft until pinion gear teeth mesh completely with flywheel ring gear teeth. Energize solenoid on solenoid shift starter.

Measure the amount of free travel (lash) between

the pinion gear teeth and the ring gear teeth. See

Figure 12. slow starter operation, or

If

lash is too tight, causing binding and

if

lash is greater than 0.035

inch (0.889 mm), lash must be adjusted.

9-6

1.

Install starter motor and torque mounting capscrews to 24 to 26 ft-lbs (33 to 35 Nm).

Install flywheel, blower housing, and cylinder air

2.

housing. For correct cylinder air housing installations (required on some models), refer to Cylinder Air Housing Clearance.

Connect battery cable and wires to starter. Connect

3. battery cables to battery. Connect ground cable last.

Engine Disassembly

DlSASSEMBLY/ASSEMBLY

When complete engine disassembly is necessary, first remove all complete assemblies. Individual assemblies such as fuel pump and carburetor can be disassembled and repaired at another time. gear.

Suggested Disassembly Order

1. Drain crankcase.

2. Disconnect all exhaust lines and electrical lines. cylinder heads.

3.

Remove engine from its mountings and place on a suitable bench or work stand.

4.

Remove all housings, shrouds, blower housings, etc.

5.

Remove flywheel, using a puller. Note position of chaff screen and venturi when removing to assure screw hole alignment on reassembly. See page

18

for further information.

6.

Remove ignition trigger ring,

with electronic ignition.

7.

Remove the gear cover, being careful to protect the oil seal from keyway damage.

8.

Remove the crank gear, using a gear puller and ring.

9.

Remove all accessories such as oil filter, starter, intake manifold, fuel lines, spark plugs, etc.

10.

Remove breaker point box.

11.

Remove oil base, oil pump and cylinder heads.

12.

Remove valves, springs, lifters, etc.

13.

Remove camshaft and gear assembly.

14.

Remove connecting rods and pistons.

15.

Remove rear bearing plate, crankshaft, and front The compression tester is used to determine the bearing. condition of valves, pistons, piston rings and cylinders.

Keep all parts in their respective orders. Keep valve assemblies together. Return rod caps to their respective pistons. Analyze the reasons for parts failure.

if

engine is equipped

Suggested Assembly Procedure

Engine assembly is normally the reverse of the disassembly procedure observing proper clearances and torques. use a torque wrench to assure proper tightness. Coat the internal engine parts with oil as they are assembled. After the internal engine parts are assembled, the engine should turn over by hand freely. Use only genuine Onan parts and special tools when reassembling your engine.

10-

1. Use the proper bearing driver to install front main bearing after coating it with a light film of oil.

2.

Insert rear main bearing in rear bearing plate.

3.

Insert crankshaft, rear bearing plate, and crankshaft

4.

Install piston and connecting rods.

5.

Install camshaft and gear assembly; align crank

gear mark with cam gear mark.

6.

Install valve assemblies, oil pump, oil base, and

7.

Install breaker point box.

8.

Install all accessories such as oil filter, starter, fuel lines and spark plugs.

9.

Install gear cover with oil seal, trigger ring (electronic ignition only) and flywheel.

10. Set breaker points (if equipped with points) to obtain proper timing.

11. Check valve clearance.

12. Install all housings and air cleaner.

13. Fill' crankcase with oil.

Operation

oil

Start engine and check

mately 15 minutes to bring engine to operating temperature. Check for oil leaks, fuel leaks and exhaust leaks. Adjust carburetor and governor for speed and sensitivity.

pressure. Run for approxi-

Testing Compression

To check compression:

1.

Run the engine until thoroughly warm.

2. Stop engine and remove spark plugs.

3. Remove air cleaner and place throttle and choke in the wide open position.

4.

Insert the compression gauge in one spark plug hole.

5.

Crank the engine and note the reading.

Refer to pressures. There may be variations due to equipment, temperature, atmospheric conditions and altitude. These pressures are for a warm engine at cranking speed (about 300 rpm).

SPEClFlCATlONS

section for compression

10-1

Tappet Adjustment

Theengine isequipped with adjustable valve tappets. The valve tappet clearance should be checked and adjusted, if necessary, at least every

200

operating hours or when poor engine performance is noticed. Adjust the valve clearance only when engine is at ambient temperature. Proceed as follows:

Remove ignition key to prevent accidental star-

1. ting.

Remove all parts necessary to gain access to

2.

valve tappets.

Remove spark plugs to ease the task of turning

3.

the engine over by hand.

4.

Place a socket wrench on the flywheel capscrew and rotate the crankshaft in a clockwise direction until the left intake valve (viewed from flywheel end) opens and closes. Continue turning the crankshaft until the TC mark on the flywheel is lined up with the TC mark on the gear cover. This should place the left piston (#1) at the top of its compression stroke. Verify that the left intake and exhaust valves are closed and there is no pressure on the valve lifters.

The correct feeler gauge for the valve adjustment

5.

(see

SPEClFlCATIONS)

tween valve stem and tappet; a

(0.05

mm) thicker gauge should not (Figure 1).

To correct the valve clearance, use a 7/16-inch

6.

should pass freely be-

0.002

inch

open end wrench to turn the adjusting screw to obtain the correct clearance. The screw is self-

locking and will stay where it is set.

A

9/16-inch

(14 mm) open end wrench is required to hold the

tappet while turning the adjusting screw.

VALVE

A

properly functioning valve system is essential'

good engine performance. All engines utilize an

SYSTEM

for

L-

head type valve design as shown in Figure 1. Access

to the valve system can be obtained by removing

cylinder heads and the valve covers on top of the engine.

A

valve spring compressor must be used to

remove valves from the cylinder block. A valve stem seal is sometimes used on the intake valve

guides of some engines. This seal must be replaced

each time the valve is removed. Place valves, springs, retainers, and tappets in a rack as

they are removed from cylinder block

so

they can be identified and reinstalled in their original locations. Discard old valve stem seals and replace with new ones during assembly.

Use the following procedures to inspect and service the valve system.

Inspection

Clean carbon from the valves, valve seats, valve

guides, and cylinder block.

Valves:

Check the valve face for evidence of burning,

warpage, out-of-round, and carbon deposits.

Burning and pitting are caused by the valve failing to seat tightly. This condition is often caused by hard carbon particles on the seat. It may also be due to weak valve springs, insufficient tappet clearance; warpage, and misalignment.

i

To adjust valves on the right hand cylinder, turn

7. engine one complete revolution and again line up

mark on the flywheel and the TC mark on the gear cover. Then follow adjustment procedure given for left hand cylinder.

Replace all parts removed in Step

8.

2.

Tighten all screws securely. Torque manifold bolts to specified torque.

VALVE

SEAT

VALVE

FIGURE

CLEARANCE

RETAINER

SPRING-

1.

VALVE ASSEMBLY

)

VALVE

\\I

VALVE

ADJUSTINGADIUSTING

SPRING

VALVE

ROTA

.TOR

YT-1005

10-2

Warpage occurs chiefly in the upper stem due to its exposure to intense heat. Out-of-round wear follows when the seat is pounded by a valve whose head is

not in line with the stem and guide. If a valve face is

burned or warped, or if the stem is worn, install a new

'valve.

Too much clearance in the intake guide admits air

and oil into the combustion chamber, upsetting carburetion, increasing oil consumption, and making heavy carbon deposits. Carbon reduces heat dissi-

pation. Clean metal is a good heat conductor but carbon insulates and retains heat. This increases combustion chamber temperatures which causes warping and burning.

Unburned carbon residue gums valve stems and causes them to stick in the guide. Deposits of hard carbon with sharp points projecting become white

hot and cause pre-ignition and pinging.

Refinish valves that are slightly pitted or burned on an accurate valve grinder. If valves are badly pitted or

have a thin margin when refacing, replace them.

Driving out old guides can damage

CAUTION

the guide or tappet bores. Be careful not to strike guide bores with driver or allow guide to strike tappet bores during removal.

Valve Guide Installation:

Run a small polishing rod covered with crocus cloth through valve guide holes to clean out carbon and other foreign materials. Place a new gasket on the intake valve guide, and coat the outer edge of each new guide with oil. Place guide,

notch-up, in cylinder block and press in until guide

stops or protrudes

box side of block. is shown in Figure

11/32

inch

(8.7

mm) from rocker

A

suggested method of installation

3.

ROD

VT-1020

FIGURE

Stems And Guides:

guides for wear (Figure

2.

VALVE STEM AND VALVE GUIDE INSPECTION

Always check valve stems and

2).

Use a hole gauge to measure the valve guide. When clearance with stem exceeds that specific in either valve

DlMENSlONS AND CLEARANCES,

or

guide or both, as may be necessary.

replace

Always regrind seat to make concentric with the newly

installed guide.

Worn valve stem guides can be replaced from inside

the valve chamber (a seal is provided behind the intake valve guides only). The smaller diameter of the tapered valve guides must face toward the valve head.

Tappets

replaceable

from

the

valve

chamber

are

also

after first removing the valve assemblies.

NUT

5/16-18

HEX, NUT

(2

2-3/8”

(60

mm)

FIGURE

3.

Valve Stem Seals:

REQUIRED)

5/8"

(16

(mm)

VALVE GUIDE INSTALLATION

Do not reuse valve stem seals. Each

\

(2

REQUIRED)

Vl-1023

time the valves are removed from cylinder block, a

new seal must be used when valve is reinstalled.

Valve Guide Removal:

Before removing valve guides,

use an electric drill with a wire brush to remove carbon and other foreign material from top surface of guides. Failure to perform this operation may result in damage to the guide bores. Drive the guides out with a hammer and valve guide driver.

CAUTION

not remove valve after seal is

installed Valve can be withdrawn

only as far as the groove in valve stem. Do not allow

valve stem seal to come in contact with groove or seal

damage will result.

10-3

Valve Spring:

Check valve springs for cracks, worn ends, distortion, and tension. If spring ends are worn, check valve spring retainer for wear. Check for spring distortion by placing spring on a flat surface next to a square. Measure height of spring and rotate it against square edge to measure distortion. If distortion exceeds

0.06

inch

(1.5

mm) replace spring. Check spring tension at the installed height for both the valve open and closed position using an accurate valve spring tester. Replace any valve spring that is weak, cracked, worn, or distorted.

Valve Seat Removal:

Remove carbon and combustion deposits from valve seat. Select proper puller size determined by inside diameter of valve seat. On some pullers use a new seat as a guide to adjust puller depth (Figure at the point where bottom

4).

Puller jaws must expand into cylinder block

of

valve seat insert rests cylinder block. Position puller on valve seat and tighten hex nut. Clamp cylinder block to a solid bench. Attach slide hammer to puller. Tighten hex nut between each blow with the slide hammer.

Valve Rotators:

Positive type valve rotators prolong valve life and decrease valve repairs. When functioning properly, the valve is rotated a fraction of a turn each time it opens. While at open position, the valve must rotate freely. There is no easy way to determine if a valve rotator is good or bad. Onan recommends that valve rotators be replaced at each major overhaul or if a build-up

of

carbon is noted on

valve face and valve seat.

Valve Seats:

Inspect valve seat inserts.

If

seats are loose, cracked or severely pitted, new ones must be installed. Remove valve seat inserts using a valve seat removal tool. If valve seat insert bores in cylinder

block are damaged or worn

so

that a press fit cannot be obtained when installing new standard size valve seat inserts, the bores must be machined for an oversize seat.

USE

NEW

VALVE

SEAT

ADJUST

PULLER

TO

DEPTH

VALVE SEAT

i

VALVE SEAT

(USE

PROPER

CHECK

FOR

THIS

BURRS

TOOL

SURFACE

BEFORE

PULLER

FIGURE

JAWS

4.

VALVE

SEAT

REMOVAL

C-1104

FIGURE

Valve Seat Installation:

5.

INSERTING NEW VALVE SEAT

After the old seat has been

removed, clean out any carbon or metal burrs from the

seat insert recess. Use a valve seat insert driver and

hammer to install the insert (Figure seat insert in

so

that the insert enters the recess evenly.

5).

Drive the valve

Make certain that the valve seat insert rests solidly on

the bottom of the recess all the way around its

circumference. To assure a tight valve seat fit and eliminate the danger

of

seat loosening in the bore, valve seat must be staked.

Insert valve seat staker into valve seat or guide in cylinder block. Using a lead hammer, strike the staking tool a sharp blow to wedge new valve securely in place. It will be necessary to refinish valve seat inserts before installing valves.

10-4

VT-1025

TAPPETS

Very little wear takes place on tappet diameters or in tappet bores. If the clearance between tappet and

in cylinder block exceeds specifications, replace

he tappet.

Inspect the tappet faces which contact camshaft lobes for roughness, scuffing, or concave wear. Replace any worn tappets.

If

tappets are worn,

inspect camshaft for wear.

VALVE FACE AND SEAT GRINDING

Some engines are equipped with a premium valve

package (aluminized intake valves). If thealuminized valve face does not clean-up using a wire brush, the valve face may be refinished. This removes the

aluminized coating from thevalve face. An aluminized valve that has been refinished will normally have a life

expectancy equal to a standard valve. If longer valve

life is required, worn or damaged valves should be

replaced with new premium valves.

Before installing new valves or previously used valves,

inspect valve seats for proper valve seating.

valves are reinstalled, the valve stems should be cleaned and valve faces ground to their specified angles of

44".

Refinish valve seats to a

When refacing valves and seats, remove all evidence

of pitting and grooving. If end of valve stem is pitted

or worn, true it and clean it up on the refacer wheel. A very light grind is usually enough to square stem and

remove any pits or burrs. The valve guide should be

'thoroughly cleaned. If valve guide is worn, or valve is

warped, the necessary parts must be replaced.

45"

If

used

angle.

Refinish valve faces to a

44"

angle on a valve refacing machine. The first cut from valve face must be a light grinding. Check if there is an unevenness of metal being removed.

If

only part of valve's face has been touched, check to see if valve is properly seated in machine or if valve is warped, worn, or distorted.

When cut is even around the whole valve face, keep

grinding until complete face is-ground clean. Be sure the correct valve face angle is maintained. When valve head is warped, a knife edge will be ground

(Figure,7) on part or all of the head due to the large amount of metal that must be removed to completely reface valve. Heavy valve heads are required for strength and good heat dissipation. Knife edges lead

to

breakage, burning, and pre-ignition due to heat

localizing on the edge. Replace any valve that cannot be entirely refaced

while keeping a good valve margin (Figure 7) or is warped, worn, or damaged in any way. The amount of grinding' necessary to true a valve indicates whether valve head is worn or warped.

WARPED

VALVE

KNIFE

WITH

EDGE

GOOD

MARGIN

KNIFE

EDGE

By grinding thevalve face and seat at slightly different angles, a fine line of contact on face and seat is obtained, eliminating the need to lap the seating surfaces. The one degree difference in angles is defined as the interference angle (Figure

6).

The seat angle is greater than that of the valve face. This assures contact at the maximum diameter on valve seat seating surface.

VT-1021

FIGURE

6.

VALVE INTERFERENCE ANGLE

1/16

rnm)

INCH

MINIMUM

M-1184

FIGURE

7.

VALVE HEAD MARGIN

(1.6

When new valve seats are installed, or previously

used seats reground, refinishing must be done with a valve seat grinder used according to the manufacturer's directions.

Valve seats should be ground with a

45

degree stone

and the width of the seat band should be 1/32 inch to

3/64

inch (0.79 to 1.2 mm) wide. Grind only enough

to assure proper seating.

Place each valve in its proper location. Check each valve for a tight seat. Make several marks at regular

intervals across the valve face using machinist's bluing.' Observe if the marks rub off uniformly when the valve is rotated part of a turn against the seat. The valve seat should contact the valve face evenly at all points. The line of contact should be at the center of the valve face.

10-5

FLYWHEEL

GEAR

COVER

Removing the flywheel is a relatively simple process, but the following procedure must be followed to avoid damage to the gear case and possible injury to the operator.

1.

Turn the flywheel mounting screw outward about two turns.

Do

WARNING

not remove the screw com-

pletely since it acts as a restrainer when the flywheel snaps loose. If the flywheel action in the wheel

is

not held by the screw, the spring

will

cause it to fly off with great

force which can cause lnjury to the operator.

2.

Install a puller bar on the flywheel (Figure

FLYWHEEL

8).

After removing the mounting screws, tap the gear cover gently with a soft faced hammer to loosen it.

When installing the gear cover, make sure that the pin in the gear cover engages the nylon lined (smooth) hole in the governor cup (Figure

9).

Turn the governor cup

so

that the nylon lined hole is at the three o’clock position. Use a small amount of grease to assist in holding governor cup in position. The smooth side of the governor yoke must ride against the governor cup. Turn the governor arm and shaft clockwise as far as possible and hold in this position until the gear cover is installed flush against the crankcase. Be careful not to damage the gear cover oil seal.

3/4

!

FIGURE

3.

Turn the puller bar bolts

8.

BLOWER WHEEL

MOUNTING

in,

alternately, until the

SCREW

cs-loo0

PULLEY

wheel snaps loose on the shaft.

Do

not use a screwdriver or

CAUTION

slmllar tool or pry behlnd the

flywheel against the gear case. The gear case

cover

Is

dle-cast material and will break If undue

pressure

4.

Unscrew the puller from the flywheel, remove the

is

applied in this manner.

flywheel mounting screw and washer and pull the flywheel off the shaft. Take care not to drop the wheel.

A

bent or broken

fin

will destroy the

balance. Always use a steel key for mounting the

flywheel.

ROTATE

GOVERNOR

SO

THAT ROLL PIN

INTO

FITS

METAL LINED

HOLE

OR

BUSHING

IN THE

CUP

THE

PLASTIC

FIGURE

CUP

I

9.

GEAR

COVER

GOVERNOR ARM

GOVERNOR

IF

FEELER

BALL

HOLE

WILL

HAS

ENTER

ASSEMBLY

AFT

SHAFT

10-6

ASSEMBLED

DIMENSION

ON

DRAWING

BE

AS

INDICATED

SNAP

THE

SHOWN

WILL

CENTER

RING

CAMSHAFT

GEAR

RIGHT

INSTALLATION

OF

BALL SPACER

WRONG

C-1107

n

GOVERNOR

CUP

GOVERNOR

FLYBALL

GOVERNOR CUP

CAMSHAFT

FIGURE

wITH the gear cover removed, the governor cup can be

taken

off

after removing the snap ring from the camshaft center pin. Catch the flyballs while sliding the cup (Figure

10).

Replace with a new part any flyball which is grooved or has a flat spot; the ball spacer

if

its arms are worn or otherwise damaged; the gear/spacer assembly on gear hub, and the governor cup

if

the race surface is grooved or rough. The governor cup must be a freespinning

fit

on the camshaft center pin, but without any

excessive play.

If

replacing the ball spacer, be sure to position it

arm is lined up with the space on the camshaft gear (if

your camshaft gear does not have a space in it,

disregard this paragraph).

If

the ball spacer arm is not lined up with the space in the camshaft gear, a flyball can slip into the space and cause engine racing and governing problems (Figure

10).

When installing the governor cup, tilt the engine gear is up, put the flyballs in place (Figure

install the cup and snap ring on the center pin.

The camshaft center pin extends out

3/4

inch from the end of the camshaft. This distance provides an in-and-out travel distance of

7/32

inch

(5.6

mm) for the governor cup, as illustrated. Hold the cup against the flyballs when measuring. The camshaft center pin

10.

GOVERNOR

off

if

loose

so

an

so

the

lo),

and

(19

mm)

5

BALL

GOVERNOR

CUP

DETAILS

6

FLYBALL LOCATIONS

BALL

GOVERNOR

8

BALL

GOVERNOR

CS-1238

cannot be pulled outward or removed without damage.

If the center pin extends out too far, the cup will not hold

the flyballs properly. If the distance is less than

(5.6

mm), (the engine will race, especially at no load)

7/32"

remove' the center pin and press in a new pin.

TIMING GEARS

If

replacement of either the crankshaft gear or the camshaft gear becomes necessary, always install both gears new.

The camshaft and gear must be replaced as an assembly.

Before removing the camshaft and gear assembly, remove the cylinder head and valve assemblies. Then remove the operating plunger for the breaker points and

tappets.

To remove the crankshaft gear, first remove the snap ring and retainer washer, then attach the gear pulling ring using two

the screws alternately until both are tight. Attach a gear

puller

to

the puller ring and proceed to remove the gear.

Each timing gear is stamped with

gear teeth must mesh

coincide when the gears are installed in the engine.

When installing the camshaft gear and shaft assembly,

be sure that the thrust washer is properly in place behind the camshaft gear. Then install the crankshaft retaining washer and lock ring.

No.

10-32

so

screws (Figure

"0"

11).

Tighten

near the edge. The

that these marks exactly

10-7

CRANKSHAFT

GEAR PULLER

INSTALLING TIMING

4.

Turn the crankshaft until the piston is at the

bottom of its stroke and remove the connecting rod nuts. Lift the rod bearing cap from the rod and push the rod and piston assembly out through the

top

of

the cylinder using a hammer handle. Avoid

scratching the crankpin and cylinder wall whel

removing the piston and rod.

5.

Mark each piston and rod assembly returned to their respective cylinders after overhaul. Keep connecting rod bearing caps with their respective rods.

6.

Remove the piston rings from the piston with a piston ring spreader (Figure 13). Remove the piston pin retainer and push the piston pin out.

so

they can be

FIGURE

11.

TIMING GEAR REMOVAL AND INSTALLATION

PISTONS AND CONNECTING RODS

Observe the following procedure when removing pistons and connecting rods from the engine.

1.

Drain oil.

2. Remove the cylinder head and oil base pan from the engine.

3.

Remove the ridge from the top of each cylinder

with a ridge reamer before attempting piston

removal (Figure 12).

CAUTION

cause damage to the piston lands and break rings.

Forcing the piston from the cylinder before reaming may

FIGURE

7.

Remove dirt and deposits from the piston surfaces

with an approved cleaning solvent. Clean the piston

ring grooves with a groove cleaner or the end of a piston ring filed to a sharp point (Figure 14). Care must be taken not to remove metal from the groove

sides:

CAUTION

These materials will cause piston damage.

13.

REMOVING PISTON RINGS

Do

not use a caustic cleaning solvent

or wire brush for cleaning pistons.

FIGURE

12.

REMOVING RIDGE FROM CYLINDER

When cleaning the connecting rods in solvent, be sure to include the rod bore. Blow out all passages with compressed air.

Engines that have been fitted with oversize pistons at the factory are identified by the letter E after the serial number. Number is stamped on the cylinder block and on the unit nameplate.

0.005

inch

(0.1

3

10-8

mm)

FIGURE

14.

PISTON GROOVE CLEANING

FIGURE

15.

CHECKING RING SIDE CLEARANCE

with deep nicks, signs of fractures, scored bores or bores out of round more than inch.

2.

Use a new piston pin to check connecting rod

for wear.

A

push fit clearance is required and varies from engine to engine. If a new piston pin falls through a dry rod pin bore as a result of its own weight, replace the rod.

Fitting Pistons:

0.002

Inspection

Follow the procedures given below when inspecting pistons and connecting rods.

Piston Inspection:

1.

Inspect the pistons for fractures at the ring lands, skirts, and pin the ring lands using a new ring and feeler gauge (Figure

15).

Replace the piston when the side

clearance of the top compression ring reaches

0.008

inch (0.20 mm).

2.

Replace pistons showing signs of scuffing, scoring, worn ring lands, fractures or damage from preignition. Excessive piston wear near

the edge of the top ring land indicates

preignition.

Connecting

1.

Replace connecting rod bolts and nuts with

Rod

Inspection:

damaged threads. Replace connecting rods

bosses.

Check for wear at

1.

Proper piston tolerances must be maintained

for satisfactory operation.

2.

Refer to

DIMENSIONS AND CLEARANCES

determine where to measure piston to be sure the total clearance follows specifications.

FIGURE

16.

MEASURING PISTON CLEARANCE

to

10-9

Fitting Piston Rings:

1. Install the piston ring in the cylinder bore. Invert the piston and push the ring

to

the end of ring travel, about halfway into the bore, which trues the ring end gap. Check the gap with a feeler gauge (Figure 17).

2.

The practice of filing ring ends to increase the

end gap is not recommended.

If

the ring end

gap does not meet specifications, check for the correct set of rings and the correct bore size

A

cylinder bore that is 0.001 inch

(0.03

mm) under size will reduce the end gap

0.003

inch

(0.08

mm).

Cleaning

After removing pistons, crankshaft, cylinder heads, etc., inspect block for cracks and extreme wear. If

block is still serviceable, prepare it for cleaning as

follows:

1.

Scrape all old gasket material from block. Remove oil by-pass to allow cleaning solution to contact

inside of oil passages.

Remove grease and scale from cylinder block by

2.

agitating in a bath of commercial cleaning solution or hot soapy washing solution.

Rinse block in clean. hot water

3.

to

remove cleaning

solution.

Inspection

When rebuilding the engine, thoroughly inspect block for any condition that would make it unfit for further

use. This inspection must be made after all parts have been removed and block has been thoroughly

cleaned and dried.

1. Make a thorough check for cracks. Minute cracks may be detected by coating the suspected area

with a mixture of percent light motor oil. Wipe the part dry and

immediately apply a coating of zinc oxide (white

lead) 'dissolved present, the white coating will become discolored at the defective area. Always replace a cracked cylinder block.

25

percent kerosene and 75

in

wood alcohol. If cracks are

FIGURE

17.

POSITIONING AND MEASURING OF END GAP

OF

PISTON RING

CYLINDER BLOCK

The cylinder block is the main support for all other basic engine parts. Crankshaft and camshaft are supported by the block, assuring alignment of the crankshaft and cylinder bores.

2.

Inspect all machined surfaces and threaded holes.

Carefully remove any nicks or burrs from machined surfaces. Clean out tapped holes and clean up any damaged threads.

3.

Check top of block for flatness with a straight edge and a feeler gauge.

Cylinder Bore Inspection

Inspect cylinder bores for scuffing, 'scratches, wear, and scoring. If cylinder bores are scuffed, scratched, scored, or worn, they must be rebored and honed for the next oversize piston.

When the appearance of cylinder bores is good and there are

no

scuff marks, check cylinder bore for wear

or out of roundness as follows:

1,

Check cylinder bore for taper, out of round, and wear with a cylinder bore gauge, telescope gauge or inside micrometer. These measurements should be taken at four places, top and bottom of piston ring travel, parallel and perpendicular to axis

of

crankshaft.

2.

Record measurements taken at top and bottom

of

piston travel as follows (Figure 18).

10-10

A.

Measure and record as

“A”

the cylinder bore diameter (parallel to crankshaft) near the top of cylinder bore where greatest amount of wear occurs.

TOP

END

OF

CYLlNDER

B.

Also

measure and record as

“B”

cylinder bore diameter (parallel to crankshaft) at the bottom of piston travel.

C.

Measure and record as

“C”

cylinder bore diameter (perpendicular to crankshaft) near the top of cylinder bore where greatest amount of wear occurs.

D.

Also

measure and record as “D” cylinder bore diameter (perpendicular to crankshaft) at the bottom of piston travel.

E.

Reading “A” subtracted from reading reading

“C”

subtracted from reading “D”

“B”

indicates cylinder taper.

If

cylinder taper exceeds that specified in

DIMENSIONS AND CLEARANCES

hone cylinder

to

the next oversize.

rebore and

and

0490

BOTTOM

I

OF

I

RING

TRAVEL

RING

WEAR

A

REA

F.

Reading reading whether or not cylinder is out of round. round exceeds that specified in

AND CLEARANCES

rebored and honed to the next oversize.

“A”

compared

“B”

compared to reading

the cylinders must be

to

reading

“D”

DIMENSIONS

“C”

and

indicate

If

out

of

A

reboring machine is used when going to oversize pistons.

Reboring the Cylinder

Rebore and hone engine whenever cylinder bore is

if

worn, damaged, out of round, or exceeds specifications.

A

worn cylinder bore should

cylinder taper

be resized to the smallest standard oversize diameter at which it will clean up. The final finish and bore diameters should then be obtained by honing. Final

bore diameter should equal the standard diameter added to the oversize.

lf boring

CAUTION

face that may

it will produce a rough cylinder sur-

not

clean up even when honed. Boring

bar

is

operated

incorrectly

should be done only by qualified service personnel

who are careful in their work.

FIGURE

18.

METHODS

OF

A

CYLINDER

OF

MEASURING THE DIAMETER

BORE

After boring to the correct oversize cylinder bore dimension piston and ring clearance should be appropriate. There is no need to adjust or “fit” pistons and rings.

When reboring cylinders, take the following precautions:

1.

Make, sure cutting tool is properly ground before using it.

2.

Be sure top of engine block is smooth and deposit

free.

10-1

1

3.

Clean base of boring bar before bar is set up. Deposits under boring bar will cause it to tilt and

the cylinder will be distorted after boring.

4.

Make an initial rough cut, followed by a finish cut.

Then hone cylinder bore to the specified oversize.

Deglazing Cylinder Bores

Deglaze the cylinder bores

if

there are no scuff marks and no wear Or out of round beyond specifications before installing new rings. Deglazing gives finish, but does not enlarge cylinder diameter,

a

so

the

original pistons with new rings may still be used.

Honing Cylinders (Using Precision Hones)

Refer to hone manufacturer's recommended grit size to produce specified surface finish of

20

to

40

RMS.

Too rough of a finish will wear out the rings and too smooth of a finish can retard piston ring seating.

1.

Position block solidly for either vertical or horizontal honing. Use either a drill press duty drill which operates at approximately

450

rpm.

2.

Follow hone manufacturer's instructions for the use of oil

or

lubricant on stones. Do not use

or

heavy-

250

to

lubricants with a dry hone.

3.

Insert hone in bore and adjust stones to

fit

snugly

to the narrowest section. When adjusted cor-

rectly, the hone should not shake

or

chatter in cylinder bore, but will drag freely up and down when hone is not running.

4.

Connect drill

to

hone and start drill. Feel out bore for high spots, which cause an increased drag on stones. Move hone up and down in bore with short overlapping strokes about

40

times per

minute. Usually bottom of cylinder must be

worked out first because it is smaller.

As

cylinder

takes a uniform diameter, move hone up and

down all the way through cylinder bore.

The reason for deglazing a cylinder is

to

provide

cavities to hold oil during piston ring break-in.

1. Wipe cylinder bores with a clean cloth which has been dipped in clean, light engine oil.

2.

Use a brush type deglazing tool with coated bristle tips to produce a crosshatch pattern in the

cylinder bore.

3.

Use a

slow

speed drill to drive the deglazing

Move deglazing

tool

up and down in cylinder (10

tool.

12 complete strokes) rapidly enough to obtain a

crosshatch pattern (Figure 19).

to

5.

Check diameter of the cylinder regularly during honing.

A

dial bore gauge

is

the easiest method

but a telescoping gauge can be used. Check size at six places in bore; measure twice at top, middle and bottom at 90-degree angles.

6.

Crosshatch formed by the stones should form an

included angle of achieved by moving the rotating hone

rpm) up and down in cylinder bore about

23

degrees. This can be

(250

to

40

per minute.

7.

Clean cylinder bores thoroughly with soap, water and clean rags.

A

clean white rag should not

become soiled on wall after cleaning is complete.

Do

not use a solvent

or

gasoline since they wash

oil from the walls but leave the metal particles.

8.

Dry crankcase and coat it with oil.

450

times

FIGURE

CAUTION

19.

CROSS HATCHING

...

Never use gasoline or commer-

cial cleaners to clean cylinder bores after deglazing or honing. These solvents will not remove abrasives from the walls. sives not removed from engine will rapidly wear rings, 'cylinder walls, and bearing surfaces of all lubricated parts.

4.

Clean cylinder bore thoroughly with soap, water and clean rags. Continue cleaning until a clean white rag shows no discoloring when wiped

through cylinder bore.

Abra-

CRANKSHAFT

Clean crankshaft thoroughly and inspect journals for

scoring, chipping, cracking, or signs of overheating. crankshaft has overheated, is scored, or excessively worn, reconditioning or replacement will be required. Examine bearing journals for cracks if overheating has occurred.

Measure crankshaft main bearing and connecting rod

journals at several places on their diameter to check for

roundness and taper. The only recommended method of reconditioning the

crankshaft is regrinding, as required to accommodate

undersize bearings. Metallizing of bearing journals is

not recommended.

If

ALIGN HOLE IN BEARING

CAMSHAFT

FIGURE

IN

BEARING BORE

BEARlNG

20.

FRONT CAMSHAFT BEARING

7/32”

FROM

(5.6

mm)

OUTSIDE

If

regrinding of crankshaft Journals is necessary the which do not require line reaming or line boring after

work should be done by a reputable machine shop

that

has suitable equipment to handle precision work of this bore

type. Undersize main bearings are available in sizes of Lockti@

0.010,

rods are available

0.040

0.020,

and

0.030

inch. Undersize connecting Use a combination bearing driver to install bearings.

in

sizes of

0.010,

0.020,

0.030

and

inch. bore with the lubricating hole (front only) in the proper

Replacement camshaft bearings are precision type installation. Clean outside of the bearing and bearing

in

Place

the block. Before

Bearing

the bearing

Mount

on

installing

on

outside

the

crankcase

cam

bearings

diameter

Over

use

of

bearing.

the bearing

position. Be sure to start the bearing straight. Press in

Whenever making major repairs on the engine, always the front bearing flush with the outside end of the

inspect the drilled passages of the crankshaft. Clean bearing bore. Front cam bearing oil hole must line up

them to remove any foreign material and to assure with oiling hole in cylinder block (Figure 20). Press in

proper lubrication of the connecting rods. the rear camshaft bearing until past the ignition plunger

hole. Lubricate bearing surfaces with oil after installing. New crankshaft main bearings are precision type which

do

not

require line reaming or line boring after installation. Use a press or a suitable driver to remove bearings. Support casting to avoid distortion and

to

avoid damaging the bearing bore during removal and installation.

Before installing main bearings, expand bearing bore by

BEARINGS

placing’ the casting in an oven heated to 200F practical, cool the precision bearing to shrink

Before installing the front main bearing, use the towelette

(94°C).

it.

included with the bearing kit to clean the outside of the

With camshaft and crankshaft removed, use a micro-

bearing and bearing bore in the block.

meter to measure diameter of bearing journals. Use a dial bore gauge or a telescopic gauge and micrometer

to measure inside diameter of bearings. Refer to

DlMENSlON AND CLEARANCE

to determine

if

clear-

CAUTION

harmful.

Be

Breathing vapor from towelette and

prolonged contact with skin can be

sure area

is

well ventilated.

ances are within specifications.

After allowing three to four minutes for drying, apply the

Any bearing that is scored, chipped, pitted or worn beyond the specified limits must be replaced.

Locktite from the small tube to the mating surfaces of the bearing and the bearing bore. Align the oil holes in the bearing with the oil holes in the bearing bore (Figure 22).

of

Removal

the camshaft bearings requires complete disassembly of the engine: Use a press or a suitable driver to remove bearings. Support casting

to

avoid

and to avoid damaging the bearing bore

during removal and installation.

The oil passage should be at least half open. Install the bearing flush with the block, using the combination driver. Wipe off excess Locktite around the bearing.

Allow at least one hour for hardening at room

temperature.

If

10-13

FIGURE

21.

REAR BEARING END PLATE

LOCK PIN

BEARINGS

FOR

REAR BEARING PLATE

In the rear bearing plate, install the bearing flush to

1/64

inch

(0.40

mm) below the end of the bore. Be sure

to align the oil holes in the bearing with the oil holes in

the bearing bore (Figure 21). The oil passage must be least half open. Lubricate bearing after installation.

If head of lock pin is damaged, use side cutters or Easy Out tool to remove and install new pin. Oil grooves in thrust washers must face the crankshaft, and washers

must be flat (not bent). The two notches on each washer

must fit over the two lock pins to prevent riding on the crankshaft (Figure 21).

Lubricate the front main bearing lightly with oil and

insert the crankshaft. With the rear bearing plate gasket

in place and the rear plate bearing lubricated, slide the thrust washer (grooves toward crankshaft) and plate over the end

of

the crankshaft. Line up notches of thrust washer with lock pins before tightening end plate or lock pins will be damaged.

Engines shipped from the factory have separate thrust washers and main bearings for both front and rear of

engine’

Front

bearing replacement part

is

a

One piece

bearing (with attached thrust washer) as shown in

Figure

22.

Do

not add an additional thrust washer

to

this

front bearing.

FRONT MAIN

ALIGN BEARING

LOCK PINS

AND MATCH

OIL

HOLES

BEARING

BORE

CRANKSHAFT

After

the rear bearing end plate has been tightened,

using

the

torque

AND

SPECIAL

shown in Figure

DIMENSIONS AND CLEARANCES

recommended

TOOLS,

check

23.

If

there is too much endplay (see

ENDPLAY

in

ASSEMBLY

the

crank

shaft end

for minimum and

TORQUES

play

as

maximum endplay), remove the rear bearing end plate

and add

a

shim (Figure 21) between the thrust washer

and plate. Reinstall the end plate, making sure the thrust

washer and shim notches line up with the lock pins. Torque and recheck endplay

of

the crankshaft.

FIGURE

22.

FRONT BEARING INSTALLATION

FRONT MAIN

REPLACEMENT

BEARING

10-14

MEASURE ENDPLAY HERE

(REFER

FIGURE

TO

AND CLEARANCES)

DIMENSIONS

23.

CRANKSHAFT

ENDPLAY

CHECKING CONNECTING ROD BEARING

CLEARANCE WITH PLASTIGAUGE

1.

Make certain that all parts are marked or identified

so

that they are reinstalled in their original positions. Using a clean dry cloth, thoroughly clean all oil from crankshaft journal and connecting rod.

2. Place a piece of correct size Plastigauge in the bearing cap the full width of the journal surface and

about 1/4 inch (6.35 mm) off center (Figure 24).

3. Rotate the crankshaft about 30 degrees from bottom dead center and reinstall the bearing cap; tighten rod bolts

TORQUES

crankshaft.

to

the torque specified in

AND

SPECIAL TOOLS.

ASSEMBLY

Do

not turn the

4. Remove bearing cap. The flattened Plastigauge will be found adhering

to

either the bearing cap or

crankshaft.

5.

Compare flattened Plastigauge with the graduations on Plastigauge envelope

to

determine clearance.

The number within the matching graduation on the envelope indicates total clearance in millimetres or thousandths

of

an inch.

MOUNTING

OF

GEAR

FACE

COVER

FIGU’RE

The bearing plate must be removed

seal (Figure

24.

MEASURING BEARING CLEARANCE

OIL

SEALS

to

replace the oil

25).

Drive the oil seal out from the inside.

Before installing seals, fill the space between lips with a multi-purpose grease. This will improve sealing.

When installing the gear cover oil seal, tap the seal inward until it is

.645

inch

(1

6.4 mm) from the front of the

gear cover. When installing the bearing plate oil seal, tap the seal

into the bearing plate bore

to

bottom against the shoulder in the plate bore. Use a seal expander or place a piece of heavy paper around the end when replacing the bearing plate seal. Remove the paper as soon as the plate

REAR

BEARING

of

the crankshaft,

to

avoid damaging the

is

PLATE

THIS

SURFACE

CLEANED

SEALING

BEFORE

SHOULD BE

OF

ALL

OLD

COMPOUND

INSTALLING

in place.

SEAL.

FRONT

GEAR

COVER

GEAR

COVER

FIGURE

THIS

SHOULD

OLD

BEFORE

OIL SEAL

25.

GEAR

COVER

BE

SEALING COMPOUND

INSTALLING

GEAR COVER AND REAR BEARING PLATE

SURFACE

CLEANED

OF

SEAL.

ALL

10-15

REAR

OIL

BEARING

OIL

SEALS

SEAL

DRIVE SEAL OF THE

PLATE

OR

PRESS

TO

SHOULDER

PLATE

OIL

BORE

-1163

PISTON ASSEMBLY

Lubricate all parts with engine oil. Position piston on its respective rod and install the

pin. Install the rings on the piston’s starting with the oil

26).

control ring (Figure to prevent twisting or excessive expansion of the ring.. Compression rings have a dot or the word “top” on one side of the ring to indicate which side

faces the top of the piston. Unmarked piston rings

can be installed either way. The oil control ring has an expander; install the expander first and then close until the expander ends butt. The joint should be

180

degrees from the gap of that ring.

Use a piston ring spreader

OIL

HOLE

TOWARD

CAMSHAFT

CT-1077

FIGURE

INSTALLATION OF PISTON

1.

Turn the crankshaft to position the number one rod

26.

PISTON RINGS

IN

CYLINDER

bearing journal at the bottom of its stroke.

Lubricate the number one piston assembly and

2.

of

inside compressor (Figure

3.

Position the piston and rod assembly in the cylinder

the cylinder. Compress the rings with a ring

27).

block. Notched side of connecting rod must face camshaft; rod bolts must be off-set toward outside of block.

4.

Tap the piston down into the bore with the handle end of a hammer until the connecting rod is seated on the journal (Figure

27).

Install the bearing cap on the rod. Install and tighten the nuts evenly, in steps, to the specified torques.

lQl6

FIGURE

5.

The bearing cap must be tapped to properly align it

27.

INSTALLING PISTON AND

CONNECTING

ROD

with the rest of the connecting rod. Clearance varies on the journal

6.

Install the remaining piston and rod in the same

if

this is not done.

manner. Crank the engine over by hand to see that

all bearings are free.

7.

Install the oil base with a new gasket.

8.

Install the cylinder heads. See

Cylinder Head

section for torques and torquing procedure.

9.

Replace oil and break in engine.

CYLINDER

HEADS

,Remove the cylinder heads for lead cleaning and

gasket change at least every

250

hours,

engine performance is noticed.

1.

Use a

1/2

inch

(13

mm) socket wrench to remove

cylinder head nuts. Lift heads off.

Do

CAUTION

not torque or remove heads

when they are hot. Warpage

may occur. The gasket surface must be below

100"

F

before removal. At temperatures above

100"

F,

the gasket will become gummy and difficult to remove from the surface of the block and cylinder head.

2.

After removing heads, clean out all carbon deposits. Be careful not to damage the outer sealing edges where gaskets fit. The heads are made of aluminum and can be damaged by careless handling.

3.

Use new head gaskets and clean both the heads and thecylinder block thoroughly where the head gaskets rest.

4.

Place a head gasket on the cylinder head and align the stud holes holes

in

the cylinder head. While holding the

in

the gasket with the stud

gasket against the cylinder head, carefully install the cylinder head on the engine.

Do

to slide the gasket over the studs without the cylinder head behind it or the gasket may tear.

f-

5.

Install a flat washer, two compression washers, and nut on each of the top six studs(see Figure for correct sequence). When properly installed,

of

only the outside edges ers will be in contact with each other. Install a flat washer and nut on each of the

the compression wash-

four

or

when poor

not attempt

28

bottom studs.

6.

Follow the head torque sequence shown in Figure

29

tightening all nuts to 5 ft-lbs

10

ft-lbs

(14

ASSEMBLY

Nm),

then to the torque specified in the

TORQUESsection. Recheck all nuts for

(7

Nm), then

correct torque.

LEFT CYLINDER RIGHT CYLINDER

FIGURE

CAUTION

29.

HEAD BOLT TIGHTENING SEQUENCE

Too much torque will flatten the

compression washers and could

result in engine damage.

7.

Recheck torque before engine has run a total of

50

hours.

COMPRESSION

WASHERS

6

FIGURE

LONG

28.

STUDS/HEAD

CYLINDER HEAD

WASHERS

HEAT TREATED

4

SHORT

WITH

COMPRESSION

.HARDENED

WASHERS

STUDS/HEAD

HEAD

GASKET

Do

CAUTION

not torque or remove heads

when they are hot. Warpage

may occur. The gasket surface must be below

100F

100"

cult to remove from the surface

before removal. At temperatures above

F,

the gasket wlll become gummy and dlffi-

of

the block and

cylinder head.

CYLINDER HEAD STUD TEST

AND REPLACEMENT PROCEDURE

This cylinder head stud replacement procedure should be used whenever replacing any of the top six studs on the block. The use of Helicoil is not a recommended repair procedure. cylinder block must be replaced. Graphoil head and intake manifold gaskets should also be used when replacing cylinder head studs.

If

a Helicoil has been used, the

COMPRESSION

WASHERS

HEAT

TREATED

NUTS

Parts

Part

Required

No.

Description

520-091 2 Step stud

1

10-2987 Head gasket

154-221

9

Intake manifold gasket

420-0398 Drilling fixture (Reusable tool)

1.

Disconnect the spark plug wires and remove the spark plugs and cylinder head air shrouds from each cylinder.

2.

Remove the nuts and compression washers (do not remove the flatwashers) from the top six studs on each cylinder head (Figure 30). Each stud will have two compression washers and one flatwasher arranged in the sequence shown

Do

not remove the nuts from the bottom four studs

in

Figure 31.

before the test procedure is completed.

USE

STUDS

SHOWN

ABOVE

FOR

SECTION 1 STUD

LINE

TEST

HARDENED

WASHERS

HEAD

GASKET

6

LONG

STUDS

TORQUE

TO

12

FIGURE

TOP

LB-FT.

(TOP)

SIX

NUTS

(COLD)

31.

CYLINDER HEAD STUDS

4

SHORT STUDS

TORQUE

NUTS

BOTTOM

TO

15

LB-FT.

(BOTTOM)

FOUR

3. Replace the nuts and then test the top six cylinder head studs by tightening (use an accurate torque

wrench) each nut to 30 ft-lb (40 Nm) of torque.

Make a note of any studs that cannot be tightened

to 30 ft-lb of torque.

LEFT CYLtNDER

FIGURE

NUMBERS

TIGHTENING

CYLINDER

30.

RIGHT

INDICATE CORRECT

SEQUENCE

HEAD

CYLINDER HEADS

NUTS

FOR

CYLINDER

-10-18

4.

Remove the cylinder-head nuts, flatwashers,

cylinder head, and head gasket. Discard the head gasket and remove any studs that could not be torqued

to

30 ft-lb

(40

Nm) without thread pull

out.

5.

Examine the gasket surfaces of the block and

cylinder head for distortion or irregularities that could cause leakage. Check the head and block

for warpage by laying a straight edge over the

length of the gasket surface. If a

0.005

inch feeler gauge fits between the straight edge and gasket surface, the part must be replaced or milled flat.

maximum of 0.010 inch may be machined from

the cylinder block or head.

A

On some engines, it is possible that a groove from the old head gasket fire ring may be impressed into the head and/or block.

If

this is the case, essential that the part be replaced or milled to remove the imperfection.

If

all of the top six studs accepted 30 ft-lb of torque without pulling out, the new head gasket may be put on without replacement

of

the studs.

this is the case, skip steps 6 through 12.

Tool

6. Fit the special repair fixture (Onan

to

the surface of the block. Use the studs shown in

#420-0398)

Figure 32 and two cylinder head nuts to secure

fixture to head

of

block.

Some applications may require that three or four

flatwashers be placed over the studs between the

block and fixture block. This will be necessary

to

space the fixture away from the

if

the fixture does not

clear the sheet metal scroll backing plate.

7.

Insert the small size bushing into the fixture over the

it

hole(s) with damaged threads and lock

in place. With the bushing as a guide, drill out the damaged threads using a 27/64 size drill bit.

holes on the fourth fin (Figure 33). TOP

of the block, it will be necessary

SIDE

of the block, drill through to the

If

drilling out the holes at the

If

drilling out the

to

remove the corresponding intake or exhaust manifold. The drill bit should penetrate completely into the port but should not contact the opposite wall of the port

(Figure 33).

8.

Replace the small bushing with the large bushing and lock into place. Using a 1/2-13 tap, carefully form the threads, making sure there are full

threads the entire length of the hole.

it

is

If

14.

Blow out all residual debris and metal chips using

PSI

low pressure (35

or less) air.

If

a hole was drilled into either the exhaust or intake port, open the valve on that port and blow

it

out thoroughly. Replace manifold if removed during the drilling and tapping operations.

c-1009

FIGURE

INTAKE

32.

REPAIR FIXTURE

PORT

ARROWS

USE

INDICATE

FOR

ATTACHING

STUDS TO

FIXTURE

9. After all drilling and tapping is completed, remove the special fixture and repeat the same operation on the other cylinder if necessary.

10. Remove the ridge around all new holes using a flat file or a chamfer 1/32

to

45"

chamfer tool. When using a

tool,

the depth of the chamfer should be

1/16 inch deep.

11. Apply screw thread retaining compound (Locktite 242)

to

the large end of each new step stud. Install the stepped replacement stud, making sure the entire stepped portion is below the gasket surface.

12. When putting a stepped stud into the hole that penetrates into the exhaust port,

it

will be neces-

sary to cut approximately 3/16 to 1/4 inch (3 threads) off the stepped portion of the stud.

part

of

this stud may extend into the exhaust port

No

or it will interfere with the exhaust manifold assembly.

13. Turn engine

so

that both valves are closed. Using a flat scraper and/or wire brush, remove all lead and carbon deposits from the top

of

the piston,

valve area, and cylinder head combustion cham-

ber.

FIGURE

33.

DRILLING PROCEDURE

c-I010

10-19

ALIGNING BLOWER WHEEL, VENTURI

AND CHAFF SCREEN

It may be difficult to line up the screw holes in the

blower housing chaff screen with those and those in the blower wheel if these parts are separated without noting their relative positions. The holes will match up if the parts are aligned as shown in Figure

SCREW

THROUGH

SCREW HOLES ALIGN

THROUGH PART DIAMETER

34.

HOLES ALIGN

PART DIAMETER

BLOWER WHEEL

in

the venturi

VENTURI

CHAFF SCREEN

POSITION PARTS WITH ALIGNED

SCREW HOLES AT TOP

FIGURE

34.

BLOWER WHEEL, VENTURI AND CHAFF SCREEN ALIGNMENT

10-20