927-0752 Onan MCCK

927-0752

RCCK

SPEC A

WCCK Spec A-H

5-a4

Prinled in U.S.A.

Service

Manual

Engine

Safety

Precautions

It is recornmended that you read your engine manual and become thoroughly acquainted with your equipment before you

start

the engine.

W ~ h i s used throughout this manual

to

warn

of injury.

1 l-

This symbol refers

to possi6le

equip-

ment damage.

Fuels, electrical equipment, batteries, exhaust gasesand mov-

ing

parts present potential hazards that could

result in

serious, personal injury.Take care

in

following these recommended procedures.

SafetyCodes

.

0

All local, state and federal codes shoukl be consulted and complied with.

This engine is not designed or intended for use

in

aircraft.

Any

such use is at the owner‘s sde

risk.

General

0

Provide appropriate fire extinguishers and install them in convenient locations.

Use

an extinguisher rated

ABC

by

NFPA.

0

Make sure that all fasteners on the engine are secure

and

accurately torqued. Keep guards

in

position over fans, driving belts, etc.

0

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

Protect Against Moving Parts

0

Do

not wear loose clothing

in

the vicinity of moving parts, such

as PTO

shafts,

flywheels, blowers, couplings,

fans,

beits, etc.

0

Keep your hands

away

from

moving parts.

Batteries

0

Before

starling work

on

the engine, disconnect batteries to

prevent

inadvertent

starting

of

the engine.

0

DO NOTSMOKEwhile servicing batteries. Lead acid batteries give off a highly explosive hydrogen gas which can be ignited by flame, electrical arcing or by smoking.

0

Verify battery polarity before connecting battery cables.

Connect negative cable last

Fuel

System

0

DO

NOT

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.

0

Fuel lines

must

be of steel piping, adequately secured, and free from leaks. Piping at the engine should be ap- proved flexible line.

Do

not use copper piping for flexible lines

as

copper will

work

harden and become brittle enough to break.

Be sure all fuel supplies have a positive shutoff valve.

Exhaust System

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

0

DO

NOT use exhaust gases to heat a compartment.

0

Make sure that your exhaust system is free of leaks. En- sure that exhaust manifolds are secure and are not warped by b o b

unevenly

torqued.

Exhaust G a s

Is

Deadly!

Exhaust gases contain carbon monoxide, a poisonous gasthat migM cause unconsciousness and death.

It

is an odorless and colorless gas formed during combustion

of

hydrocarbon fuels.

Symptoms of carbon monoxide poisoning are:

0

0

Dizziness

Headache

Weakness and Sleepiness

0

0

Vomiting

Muscular Twitching

Throbbing

in

Temples

If you experience

any

of

these symptoms, get out into fresh immediately, shutdown the air

unit

and do not use until

it

h a s been inspected.

The best protection against carbon monoxide inhalation is proper installation and regular, frequent inspections of the complete exhaust system.

If you notice a change

in

the sound or

ap-

pearance of exhaust system, shut the

unit

down immediately and have it inspected and repaired at once by a competent mechanic.

Cooling

System

0

Coolants under pressure have

a

higher boiling

pointthan water. DO

NOT

open

a radiator pressure cap when

cool-

ant

temperature is above

212

degrees or while engine is running.

F

(1 00 degrees

C)

Keep The

Unit And

Surrounding Area Clean

0

Make sure

that oily

rags are not left on or near

the

engine.

0

Remove all unnecessary grease and

oil

from the

unit.

Ac- cumulated grease and oil can cause overheating and subsequent engine damage and present a potential fire hazard.

,

,

*

* by any means, is strictly prohibited.

Table of Contents

TITLE

PAGE

General Information

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

2

Specifications

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

3

Dimensions and Clearances

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

4

Assembly Torques

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

6

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

6 Special Tools

Engine Troubleshooting

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

7

RCCK Installation.,

RCCK Fuel System

MCCK Fuel System

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

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

8

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

15

Ignition System

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

28

Battery Charging System

OilSystem

RCCK Cooling System

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

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

33

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

30

35

MCCK Cooling System

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

36

Starting System

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

41

Engine Disassembly

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

46

Wiring Diagram

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

56

I

WARNING

h

INCORRECT SERVICE OR REPLACEMENT

OF

PARTS MIGHT RESULT IN

SEVERE PERSONAL lNJURY AND/OR EQUIPMENT DAMAGE

.

SERVICE

PERSONNEL MUST BE QUAllFlED TO PERFORM ELECTRICAL AND/OR

MECHA NlCA L SERVICE

.

1

Redistribution or publication of this document, by any means, is strictly prohibited.

General Information

I NTR 0 D

U

ON

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.

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 end of the engine is the front end

so

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 inter- connected.

A

parts catalog (available at the dealer level) contains detailed exploded views of each assembly and the individual piece part numbers and their proper names for ordering replacement parts.

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 nameplate. Always use this number and the engine serial numberwhen making reference toyour engine.

How to interpret MODEL and SPEC NO. on generator set engines.

1 2 3 4 5 6

1.

Indicates kilowatt rating.

2. Series identification.

3.

Voltage code of the generator.

4. Method of starting: A-automatic, R-remote electric starting, and E-electric starting.

5.

Factory code for designating optional eguipment,

6.

if any.

Specification letter which advances when the factory makes production modifications.

How to interpret MODEL and SPEC NO on industrial engines.

T-T’T

1 2

3

4

1

1.

Factory code for general identification purposes.

2.

Specific Type:

MS-ELECTRIC

starting with stub shaft, starter and generator.

3.

4.

Factory code for optional equipment supplied.

Specification (Spec Letter) advances with factory production modification.

Y


Specifications

.

.

*

SPECIFICATION

Number of Cylinders

Bore

Stroke

Displacement

Compression Ratio

Rated Speed (Maximum)

Power at

Rated Speed

Oil Filter

Oil Capacity Without

Filter

Oil Capacity With

Filter Change

Crankshaft Rotation

(viewed from flywheel)

Governor

Valve Clearance (Cold)

Intake

Exhaust

Spark Plug Gap

Breaker Point Gap

-

Static

(Full Separation and Engine Cold)

Ignition Timing

This

manual contains

SI metric equivalents that follow immediately in parentheses after the

US. of measure.

UNIT OF

MEASURE

in

(mm) in

(mm) cu in

(cm3)

RPM

BHP

(kW)

Qt

(litre)

Qt

(litre) in

(mm) in

(mm) in

(mm)

in

(mm)

BTC

MCCK

2

3.250

(82.55)

3.000

(76.2)

49.8

(816)

7.0 to 1

1800

13.0

(9.7)

Full Flow

4

(3.8)

N A

N A

SERIES

Full

Flow

3.5

(3.3)

4.0

(3.8)

RCCK

2

3.250

(82.55)

3.000

(76.2)

49.8

(81

6)

7.0 to 1

3900

19.5

Clockwise Clockwise

Mechanical

0.012

(0.30)

(0.30)

0.025

(0.64)

0.020

(0.51 )

20"

0.012

(0.30)

0.01 2

(0.30)

0.025

(0.64)

0.020

(0.51

)

20"

3


Dimensions and Clearances

.

All clearances given at room temperature

of

70°F

.

All dimensions i n inches (approximate millitnetre dimensions in parentheses) unless otherwise specified

.

DESCRIPTION

MINIMUM

Inches

MAXIMUM

(mm) Inches

(mm)

CYLINDER BLOCK

Cylinder Bore Honed Diameter

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

Maximum Allowable

Taper

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

Out-of-Round

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

Main Bearing Inside Diameter (Without bearing)

Main Bearing Inside Diameter (Installed)

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

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

Camshaft Bearing Bore (Bearing installed)

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

CRANKSHAFT

Main Bearing Journal Diameter

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

Main Bearing Clearance

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

Connecting Rod Journal Diameter

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

Crankshaft End Play

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

3.2490

2.1 87

2.0020

1.3760

1.9992

0.0025

1.6252

0.006

(82.525) 3.2500 (82.550)

(55.55)

0.005 (0.1

0.002 (0.051)

2.188 (55.58)

(50.85) 2.0030 (50.88)

(34.95) 1.3770 (34.98)

(50.78) 2.0000 (50.80)

(0.064) 0.0038 (0.097)

(41.28) 1.6260 (41.30)

(0.1 0.01

2

(0.305)

CONNECTING ROD

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 to Crankshaft Clearance

Nodular Iron

Rod

Aluminum Rod

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

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

1.7505

0.0020

0.81 15

0.7504

0.0005

0.0020

CAMSHAFT

Bearing Journal Diameter

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

Bearing Clearance

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

End Play

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

Camshaft Lift

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

1.3740

0.0030

PISTON

Clearance in Cylinder

Measure

90"

to pin

0.10

inch below oil ring

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

Piston Pin Bore

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

0.0025

0.7502

Ring

Groove

Width

Top 1 Compression Ring

No

.

2

Compression Ring

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

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

No

.

3

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

0.0960

0.0955

0.188

(44.46) 1.7510 (44.48)

(0.051) 0.0160

(0.406)

(20.61) 0.8125

*

(20.64)

(19.05)

0.7508 (19.07)

(0.013) 0.0023 (0.058)

(0.051) 0.0033 (0.084)

(34.90)

1.3745 (34.91)

(0.038)

0.0030 (0.076)

(0.076)

0.0120 (0.305)

0.300 (7.62)

(0.064) 0.0045

14)

(1 0.7506 (1 9.065)

(2.438)

0.0970 (2.464)

(2.426) 0.0965 (2.451)

(4.775) 0.189 (4.801)

.

*

4


1

1

DESCRIPTION

MINIMUM

Inches (mm)

PISTON PIN

Clearance in Piston

Clearance in Connecting Rod

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

Diameter

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

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

PISTON RINGS

Clearance

Top Groove

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

Ring End Gap in Cylinder

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

INTAKE VALVE

Stem Diameter

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

Clearance (Stem to Guide)

Valve Face Angle

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

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

0.0002

0.7500

0.002

0.01 0

0.3425

INTAKE VALVE SEAT

Valve Seat Width

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

Valve Seat Angle

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

EXHAUST VALVE SEAT

Seat Cylinder Head Bore Diameter

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

Seat Outside Diameter

Valve Seat Width

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

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

Valve Seat Angle

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

0.031

€XHAUST VALVE

Stem Diameter

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

Clearance (Stem to Guide)

Valve Face Angle

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

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

0.3410

0.0025

1.1890

1.1920

0.031

VALVE GUIDE

Inside Diameter

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

TAPPET

Body Diameter

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

Bore Diameter

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

Clearance in Bore

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

VALVE SPRINGS INTAKE AND EXHAUST

Valve Spring Free Length (Approx.)

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

Valve Spring Length

Valve Open

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

Valve Closed

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

Spring Load

@

1.375

inch (Valve Closed)

Spring Load

@ I

1.125

inch (Valve Open)

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

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

0.344

0.7475

0.7505

0.001 5

38 ib

.

71

Ib

GEAR BACKLASH

Timing Gear

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

Oil Pump Gear

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

0.002

0.002

MAXIMUM

Inches

(mm)

Thumb Push Fit

(0.005)

0.0007

(1 0.7502

(0.051) 0.008

(0.254) 0.020

(8.70) 0.3430

(0.025)

0.0025

44"

(0.787) 0.047

45"

(8.661) 0.3415

(0.064)

0.004

44"

(30.20)

I

1900

(30.28)

1

.

.

(0.787)

0.047

6"

.

(8.74) 0.346

(1

8.99) 0.7480

(19.06) 0.7515

(0.038) 0.003

1.662

.

(42.21)

1

.

1.375 (34.93)

.

79 Ib

(0.051)

0.003

(0.051) 0.005

(19.06)

(0.203)

(0.508)

(8.71)

(0.064)

(8.674)

(0.102)

(30.23)

(30.30)

(1.194)

(8.79)

(19.00)

(19.09)

(0.076)

(19

kg)

(0.076)

(0.127)


5

Assembly Torques

The torque values given in Table

I

have been determined for the specific applications. Standard torque values must not be used where those listed inTable1 apply. The engine assembly torques given here will assure proper tightness without danger of stripping threads. All threads must be clean and lubricated with new engine oil before torquing.

Check all studs, nuts, and capscrews, and tighten as required to keep them from working loose. Refer to the PARTS MANUAL for the location of washers and capscrews.

TABLE

1.

TORQUE

DESCRIPTION

Cylinder Head Capscrews

Rear Bearing Plate..

Connecting

Rod

Bolt

....

.........

Iron Rod

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

Aluminum Rod

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

Flywheel Capscrew

..........

Starter Mounting Bracket to

...........

Oil Base Screws

Gear Case Cover

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

Oil Pump..

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

Intake Manifold

Exhaust Manif

o

Id

Oil Base..

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

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

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

SPECIFICATION

E#

I

-1 k Nm

29-31

20-25

27-29

24-26

35-40

25-35

10-13

7-9

15-20

14-17

43-48

(39-42)

(27-34)

(37-39)

(33-35)

(48-54)

(34-47)

(14-18)

(10-12)

(20-27)

(1 9-23)

(58-65)

6

Special Tools

The following special tools are available from Onan.

For further information see TOOL CATALOG

900-0079.

Valve Seat Driver

Valve Guide Driver

Oil Guide

and

Driver

Combination Bearing Remover (Main and Cam)

Combination Bearing Driver (Main and Cam)

Flywheel Puller

6


.

Engine

Troubleshooting

7


RCCK Installation

GENERAL

The type of installation can affect the life of the engine, the cost of operation and the frequency of necessary service. Plan the installation carefully to ensure the best performance.

Due to the great variety of uses, for the engine, these installation instructions are typical and general in nature. Use the installation recommendations given as a general guide, improvising or altering as necessary.

MOUNTING

There are several acceptable methods of mounting the engine. Among factors to be considered are: location, method of coupling the engine to the load, type

of

foundation or support, etc. The engineshould be mounted level if possible. Maximum operation angle is 15' sideways,

30'

front to rear tilt. If the engine will operate at an angle, besure to re-mark the oil level indicator to compensate for the tilt.

VENT1 LATl ON

The engine must be provided with asupply of fresh air for radiator cooling and for combustion.

Open Air Installation:

For installations where the engine is operated outside, ventilation usually is no problem. However, in protecting the engine from the elements, be sure nothing obstructs the flow of air around the engine.

EXHAUST

Vent exhaust gas outside enclosure. Shield the line if it passes through a combustible wall or partition. If turns are necessary, use sweeping type (long radius) elbows. Increase one pipe size (from manifold outlet size) for each additional 10 feet (3 m) in length.

Locate the outlet away from the engine air intake.

Plan the exhaust system carefully.

Exhaust gases are poisonous!

CARBURETOR AIR INTAKE

Proper engine efficiency depends upon a supply of fresh air to the carburetor. Under special conditions, it may be necessary to move the air cleaner off the engine, using a longer connection hoseas necessary.

For extreme dust or dirt conditions, install a special heavy duty air cleaner.

FUEL SYSTEM

The engine uses a mechanical type fuel pump which is mounted

on

top of the engine, adjacent to the carburetor. A rubber fuel line connects the fuel pump to the carburetor.

The fuel supply tank may be installed in any safe, convenient location.

If the tank is installed within the engine enclosure, provide a vent line to theoutsideof the enclosure. The top of the tank should be about

6 inches (152 mm) below the carburetor, but not more than 4 feet (1.2 m) below the fuel pump.

The installation of a fuel filter between the fuel tank and the fuel pump is recommended. Any fuel filter should be fitted with a shutoff valve and should be easily accessible for cleaning.

Fuel leaks create fire and explosion

i

personal injury or death. Always use flexibk tubing between engine and the fuel supply to avoid line failure and leaks due to vibration. The fuel system must meet applicable codes.

CONNECT TO THE LOAD

The dimensions of various power take-off shafts are as follows:

,

.

SHAFT

Standard

Rockford Clutch

DIMENSIONS

IN

INCHES

1

DIAMETER LENGTH

KEY

SIZE

1-1

I2

2-314

3/8

(38.10 mm)

(69.85 rnm)

(9.53 mm)

1-711 6 3-1 /2

318

(36.51 mm)

(88.90

(9.53 mm)

Gear Reduction

1-7/4

(31.75 rnm)

2-3/4

69.85

1 I4

rnm)

(6.35 mrn)

KEEP SHAFTS OF ENGINE

AND LOAD PARALLEL

BELT IN LOOSENED

POSITION

-

NOT

PULLING LOAD

BRACKET T O KEEP

BELT OFF ENGINE

PULLEY

8

KEEP PULLEYS ALIGNED

WITH EACH OTHER

POSITION

-

PULLING

LOAD

-

PULLEY

FIGURE

1. DRIVE BELT INSTALLATION


Belt Drive:

V-belts are preferable to flat.belts. CorfsOTf a reliable belting supplier for recommendations regarding size

of

pulleys, number

of

belts, etc., required.

A

typical belt drive installation is

shown in.

Figure 1.

.

Comply with the following installation requirements:

1.

Shafts of engine

and

load must be parallel with each other.

2. Pulleys of engine and load must be in alignment.

3. Mount engine pulleys as close to engine as possible.

4.

If installation permits, belts should run horizon-, tally.

5. Some method of disconnecting the load for starting

is

recommended. If a clutch is not used, a belt-tightener idler arrangement can be used.

Flexible Coupling: If a flexible coupling engine-to- load drive is used, the load shaft must be

in

line and

‘centered with the eng-ine shaft, Figure 2..

.

ENGINE POWER . FLEXIBLE

‘Install the clutch adapter, with drain slot downward using two cap screws 3/8-16 x 2 inches on the low& number

2

cylinder side (Cylinder nearer

~Iufck);

Install the 3/8-16. x ‘3-7/8‘inch

: & t

adapter into the engine block upper remaining hole.

Use a lockwasher on each assembly screw. Use

a

flatwasher and a lockwasher under the stud nut.

Install the crankshaft key. Remove the clutch set screw.

Install the clutch assembly (less housing) to the crankshaft, driving it on carefully with a soft-faced hammer until set screw hole is aligned. Install set screw to bottom in Crankshaft hole, then back it out one full turn. Tighten clutch retaining screws until clutch is clamped securely to crankshaft. Lock the screws and tighten the set screw.

Smear grease over splined power take-off shaft.

Position the clutch throw-out collar to align the grease fitting with the hole in the housing (number 1

‘cylinder side, horizontal). Pull the throw-out collar outward to remove tension.

Install the clutch housing

so

that

the

clutch throw-out fork engages the throw-out collar. Be sure

the

serrated shaft is properly meshed with the clutch plate. Use two cap screws 7/16-14 x 2 inches on the

lower and onecapscrew7/1&14~1-3/4inchesonthe upper number

2

cylinder side. Install the stud washer and nut. Lubricate the two grease fittings just until grease appears.

FIGURE 2 FLEXIBLE COUPLING

f

n

I

KEYWAY

3

DISCARD n

*

Reduction Gear Drive: Reduction gear drives are mounted at the factory (when ordered). The method

of

connecting the load is the same as when connecting directly to the engine shaft.

Clutch Installation: A Rockford clutch can be

in-

stalled at the factory or in the field. Install the clutch according to the following instructions and Figure

3.

Drill a 13/64 inch

(5.2

mm) hole (or filed slot) in the crankshaft for the clutch set screw. Locate center of hole 11/32 inch (9 mm) from the end and directly opposite the keyway in the crankshaft.

CRANKSHAFT STUB SHAFT

CLUTCH

ASSEMBLY

CLUTCH

HOUSING

IIY

9

A867

CLUTCH

ADAP‘IE R

.FIGURE 3.

SET SCREW

..

.

CLUTCH

INSTALLATION

TAKE-OFF

SHAFT

by any means, is strictly prohibited.

BATTERY

CONNECTIONS (Engines with

Electric

Starter)

Connect the

12-volt

battery positive cable to the engine start switch terminal. Connect the battery negative cable to the ground point

on

the engine oil

base, Figure 4.

FIGURE 4. BATTERY: CONNECTIONS

10


RCCK Fuel System

GENERAL

Satisfactory engine performance is largely aepen- dent upon correct fuel system adjustments. However, adjustments cannot fully compensate for low engine power due to wear, etc. If trouble develops, follow an orderly procedure to determine the cause before making any adjustment.

.-

.-

Adjusting the carburetor is a means of obtaining the correct fuel-to-air mixture for smooth, efficient operation. Always adjust in two steps, first the load adjustment and then the idle adjustment.

GASOLINE CARBURETORS

Before adjusting the carburetor, be sure the ignition system is working properly and the governor is adjusted. Allow the engineto warm-up before starting carburetor adjustments.

If carburetor is completely out of adjustment so the engine will not run, open both valves 1 to 1-112 turns off their seats to permit starting.

Do not force the needlevalves against theirseats.This can bend the needle.

Adjustments

1.

With no load, turn idle fuel adiustrnent out until

enginespeed dropsslightly below normal, Figure

5.

Then turn needle in until speed returns to normal.

2.-Apply a full load to engine.

3. Loosen packing nut and carefully turn main adjustment in until speed drops slightly below normal. Then turn needle out until speed returns to normal.

4.

Tighten packing nut.

. _ .

Alternate Method (No load adjustment possible)

1.

Start engine and allow it to warm up.

,

2.

Push in on governor mechanism to slow engine down to about 400 to 500 rpm.

3.

Set idle fuel adjustment screw for even operation

so

engine is firing on both cylinders and running smoothly.

4.

Release governor mechanism to allow engine to accelerate. If engine accelerates evenly and without a lag, the main adjustment is correct. If not, adjust the needle outward about

1/2 turn and again slow down the engine and release the mechanism. Continue until the engine accelerates evenly and without a time lag after releasing the governor.

D

nut

before mak- tighten the nut to a snug fit affer the adjustment has been made. This procedure makes if easier to use the carburetor adjusting fool and prevents fuel leaks around the packing nut. Fuel leaks cause hard starting because the float level becomes lower than normal.

Cleaning and RepaicTo clean thecarburetor, soak all components thoroughly in a good carburetorcleaner following the cleaner manufacturer's instructions. Be sure all carbon is cleaned from the carburetor bore, especially in the area of the throttle valve. Blow out the passages with compressed air. If possible, avoid using wire to clean out the passages.

injury if used improperly. Read all warning labels before using.

Check the adjusting needles and nozzle for damage.

If the float is loaded with fuel or damaged, replace it.

The float should fit freely on its pin without binding.

Invert the carburetor body and measure the float level, Figure6. If necessary, bend thesmall lipthatthe inlet valve rides on t o adjust float level.

FIGURE 5. GASOLINE CARBURETOR

I

A9,3

DIMENSION

SHOULD

I /%"

BE

-

3/

16"

(3.2-4.8

mm)

FIGURE

6.

CHECKING FLOAT LEVEL


A M B I E N T TEMP.

( O F )

CHOKE OPENING ( I n c h e s )

OPEN I NG

TEXT)

60 65 70

1/8 9/64.

75 80 85 90 95 100

.

CHOKE

-G

LOOSEN THIS

SCREW

AND

G 2

- ROTATE THE

ENTIRE COVER

ASSEMBLY

8 6 4

THERMAL MAGNETIC CHOKE

This choke uses a heating element and

a

heat sensitive bimetal spring to open the choke. The choke solenoid, actuated during engine cranking only, closes the choke according to ambient temperature,

Figure 6a.

If adjustment is required, use the following instructions. Choke bimetal spring must be at ambient temperature. Allow engine to cool at least one hour before setting. Adjust choke by turning the choke body, which engages a link connected to a bimetal choke spring.

CHOKE PLATE

FIGURE Sa. THERMAL MAGNETIC CHOKE SEiTlNGS

Check the choke and throttleshaftsforexcessiveside play and replace if necessary.

Remove air cleaner and adapter to expose the carburetor throat. Loosen the screw which secures the choke body. Rotate choke body clockwise to increase choke and counterclockwise to decrease choke action (leaner mixture). Refer to Figure 6a for correct choke setting according to ambient temperature. Use drill rod or shank of drill bit to measure choke opening.

Disassembly and Repair: If choke will not heat properly, check for broken heater wire, high-resistance connections, or broken lead wires to the bimetal and heater assembly. With the element at room temperature, check the heater resistance with an ohmmeter.

The resistance should be about 30.6 to

37.4

ohms for a 12 volt system. If the heater

is

defective, replace it with a new one. When the start button is engaged, the solenoid should cause thespring-loaded armature to contact the solenoid core.

. x

518

O.D. x

VJ6")

RETAINING RIN

BIMETAL AND

HEATER

ASSY

SOLENOID CORE

SOLENOID 'COIL

A076

GROUND TERMINAL

THERMO-MAGNETIC

CHOKE

GROUND LEAD

NUT ( 5 / 1 6 - 18")

-WASHER

>

SHAKEPROOF WASHER

(24/64

I D . x

9/16

O.D.

x

1/16")

FIGURE

6b.

THERMAL MAGNETIC CHOKE ASSEMBLY

12


If this does not occur, checkfor broken lead wires ora defective solenoid coil. There must be slack in the lead wires between the choke body and the bimetal and heater assembly.

The

solenoid

coil

resistance should be 2.09 to 2.31 ohms in a 12 volt system.

When replacing the cover on the thermostat and heater assembly, be certain that the choke heater lead wires have been correctly installed in the choke housing. Improper replacement

of

the lead wires can cause the choke assembly to malfunction.

The wires enter the choke assembly through a small notch that is cut in the edge of the housing. A cover holds the wires in place and prevents movement when tightened. When properly installed, the lead wires will hang freely under the bimetal coil when the choke is in either the open or closed position. The end of the heater wire sleeve should be located from

1/8 inch inside the choke housing to flush with the inside wall.

When assembling the thermo-magnetic choke, the bimetal and heater assembly is connected asfollows:

1. Lead tagged G goes to ground terminal on coil solenoid.

2. Lead tagged

H

goes to either noid core.

*

-

PARTS INCLUDED IN REPAIR

KIT.

UPPERPUMPBODY

(NOT SERVICEABLE)

*VALVE

*VALVE AND

.*DIAPHRAGM

ASSEMBLY

*MOUNTING

GASKET

'LOWER

SIDE

DIAPHRAGM GASKET

ROCKER

ROCKER ARM

LINK'^^ i?

VALVE

CAGE

RETAINER

*FUEL PUMP

ROD SPRING

BODY

FUEL PUMP

A

diaphragm type fuel pump is used. If fuel does not reach the carburetor, check thefuel pump.

Todo

this, disconnect the fu.el line at the carburetor and, while cranking the engine slowly by hand, observewhether fuel cornesthrough theline. Besurethereisfuel in the tank. If the line is open and no fuel comes throug h, the pump is defective. Failure of the pump is usually due to a leaking diaphragm valve or valve gasket, a weak or broken spring, or wear in the drive linkage. Oil diluted with gasoline may indicate a faulty diaphragm. If the operator chooses to repair the complete repair kit

is

recommended. pump rather than install a new one, the use of a

=

hazard fbaf mighf cause severe personal injury or death.

Use care when reassembling fuel pump. All parts must align perfectly or pump will leak fuel.

Fuel

Pump

Reconditioning

1.

Remove fuel lines and mounting screws holding pump to engine, Figure 6c.

2.

Makea mark with afileacrossapointwhere upper and lower body join to assure proper reassembly.

Remove four assembly screws and remove upper pump body.

3.

Turn upper pump body over and remove valve retainer screws and washers. Remove valve retainer, valves, valve springs and valve gasket, noting their position. Discard valve springs, valves and valve retainer gasket.

FIGURE

6c.

FUEL

PUMP

ASSEMBLY

13

4.

Clean pump body thoroughly with solvent and a fine wire brush. .

5.

Holding upper pump body with diaphragm surface up, place new valve gasket into cavity.

Assemble valve spring and valves in cavity.

Reassemble valve retainer. Lock in position by inserting and tightening valve retainer screws.

6. Place upper pump body assembly in a clean place and rebuild lower body.

7. Holding lower body, press down on diaphragmto compress spring under it, then turn bracket

90"

unhook diaphragm

so

it can be removed. a.

Clean lower body with a solvent and a fine wire brush.

9.

Replace fuel pump rod spring, diaphragm gasket, stand new spring in casting, position diaphragm, compress spring and turn

90"

to reconnect d iap

h

rag m.

10. Hold lower body, then place upper body on it

(make sure that indicating marks are in line) and insert the four screws. hand

DO

NOT TIGHTEN. With on lower body only, push pump leverto limit of its travel and hold in this position while tightening the four screws. This is important to prevent stretching the diaphragm.

11.

Mount fuel pump on engine, using new mounting gasket. Connect fuel lines.


ADJUSTABLE GOVERNOR

Where engine speed is governor controlled, the governor is set at the factory to allow a nominal engine speed of 2400 rprn at no-load operation

(unless another speed

is

specified when the engine is ordered). Proper governor adjustment

is

one of the most important factors in maintaining the power and speed desired from the engine, Figure 6d.

B A L L JOINT

Linkage

Check the governor arm, linkage, throttle shaft and lever for a binding condition or excessive slack and wear at connecting points.

A

binding condition at any point will cause thegovernortoact slowly and regulation will be poor. Excessive looseness will cause a hunting condition and regulation will beerratic. Work the arm back and forth several times by hand while the engine idles. Replace parts as needed.

The engine starts at wide open throttle. The length of the linkage connecting the goverorarm tothethrottle arm is adjusted by rotating the ball joint. Adjust length so with the engine stopped and tension on the governor spring, the carburetor throttle lever is wide open. This setting allows immediate control by the governor after starting and synchronizes travel of the governor arm and the throttle shaft.

.

'

SPEED ADJUSTING NUT

(TIGHTEN NUT T O

INCREASE SPEED)

SE NSlT IVlTY

8416

FIGURE 6d. GOVERNOR ADJUSTMENT LINKAGE

Speed

Adjustment

The speed at which the engine operates

is

determined by the tension applied to the governor spring.

Increasing spring tension increases engine speed.

Decreasing spring tension decreases engine speed.

The no-load speed of the engine should be slightly higher than the speed requirements of the connected load. For example, if the connected load is to turn at

2310 rpm, set the no-load speed of the engine at about 2400 rpm. Check speed with a tachometer. If a speed adjustment is needed, turn the speed adjusting nut in to increase the speed or out to decrease the speed, Figure 6d.

Before making governor adjustment, run the engine about 10 minutes to reach normal operating temperature. Be sure carburetor load and idle needles are properly adjusted before checking or adjusting governor system. For an accurategovernor adjustment,

a

reliable tachometer is required. n

or

deafh. S a y clear of rofating componenfs and ensure that profecfive shields and guards are in place and secured before operating machinery.

If the following checks

do

not remedy erratic operation, install a

new

governor spring. Springs become fatigued with age.

14

Sensitivity Adjustment

Theenginespeeddropfrom no loadtofull load must be within 100 rpm. Check the engine speed with no- load connected and again after connecting a full- rated load.

The sensitivity of the governor depends upon the position of the arm end of the governor spring.

A

series of holes in the governor arm provides for adjustment. To increase sensitivity, move the gover- nor spring toward the governor shaft.

To

decrease sensitivity, move the governor spring toward the linkage end of the governor arm.

A too-sensitive setting will result in a surging speed (hunting) condition, an alternate increase and decrease in engine speed. An opposite setting will result in too much speed variation between no- load and full-load conditions.

Always recheck the speed adjustment after a sensitivity adjustment. Increasing sensitivity will cause a slight decrease in speed and will require increase in the governor spring tension.

a

slight


r-CCK

Fuel System

’

Satisfactory engine performance is largely depend- ent upon correct fuel adjustments. However, adjustments cannot fully compensate for low engine power due to wear, etc. If trouble develops, follow an orderly procedure to determine the cause before making any adjustment.

Adjusting the carburetor is a means of obtaining the correct fuel-to-air mixture for smooth, efficient operation. Always adjust in two steps, first the load adjustment and then the idle adjustment.

Before adjusting the carburetor, be sure the ignition system is working properly and the governor is adjusted. Allow the engine to warm-up before starting carburetor adjustments.

4.

Push in on governor mechanism to slow the unit to400 to

500

rpm. Set idle needle for even operation

so

engine is firing on both cylinders and running smoothly.

A

Zenith carburetor is used on Spec B-G engines.

Carburetor adjustments are the same as the Spec A carburetor. The only difference is the location of adjustment needles (Figure 7). The main-fuel adjustment needle (A) is on the bottom of carburetor.

THROTTLE

/

FUEL IDLE

ADJUSTMENT

S T O P S C R E W 4

CARBURETOR ADJUSTMENTS

(Spec A-G)

If carburetor is completely out of adjustment so the engine will not run, open both needles 1 to 1-1/2 turns off their seats to permit starting. Do not force needles against their seats. This can bend the needle. n

exhausf gases mighf

or

death. Be sure deadly exhaust gas

is

piped outside

fo

and away,

from

windows, doors or ofher inlets building.

,

1.

Apply a full load to engine.

2. Turn in load needle (Figure 7) until engine speed

drops.

Then turn out needle until engine speed returns to normal.

3.

Remove load from engine.

4. Turn idle needle out until engine speed drops slightly.Then turn needle in until speed returnsto normal.

Alternate Method (No-Load adjustment possible)

1.

Start engine and allow it to warm up.

2. Push in on governor mechanism to slow the unit down to about 400 to 500 rpm.

3. Release governor mechanism to allow theengine to accelerate. If engine accelerates evenly and without a lag, the load needle setting is correct. If not, adjust needle outward about 1/2 turn and again slow down the engine and release the mechanism. Continue until engine accelerates evenly and without a time lag after releasing governor.

MAIN FUEL

ADJUSTMENT

A

SPEC B-G

THIS DISTANCE

1/32 INCH

AT NO LOAD

MAIN FUEL

ADJUSTMENT r

THROVLE STOP

SCREW

15

FIGURE

7.

ADJUSTING SIDEDRAFT CARBURETOR


Throttle Stop Screw Setting

Throttle stop screw is located on the throttle shaft lever (side

of

carburetor by ignition coil). It must be adjusted and set for 1/32 inch clearance over the manifold surface when the engine is running with no load. See Figure 7a.

STARTING POSITION

[

THROTTLE

STOP SCREW

IDLING POSITION

THIS DIMENSION

SHOULD BE

1/8

INCH

i

INCH

n n v ,

I LL

PLATE

SETTHIS

DISTANCE^

AT 1/32 INCH WHEN

1

PLANT

IS

RUNNING

AT NO LOAD

FIGURE 7a. THROTTLE STOP SCREW

Float Adjustment

To check float level, Figure 7b Spec

Spec A, remove the entire main fuel adjustment assembly from float bowl (unscrew large nut from float bowl. The proper level from float to bowl flange gasket is1/8inch with fuel floatweight on needleand spring. The float tab should just touch fuel inlet valve and not compress inlet valve spring. Adjust by bend- ing tab on the float.

Do

not apply excessive pressure

fo

floaf valve.

FIGURE 7c. FLOAT LEVEL ADJUSTMENT SPEC A

CARBURETOR ADJUSTMENTS

(Begin

Spec

H)

The carburetor idle and main mixture screws were set for maximum efficiency at the factory and should normally not be disturbed. If adjustments seem necessary, first besure the ignition system isworking properly and is not the source of the problem.

If adjustment

is

needed, proceed as follows:

1.

Turn both mixture screws in until lightly seated

(Figure7a), then back the idle mixture screw out

1

turn and the main mixturescrew out 1-1/4 turns.

Forcing fhemixfureadjusfmenf screw fight will damage the needle and seat Turn in on/y unfil right fension can be felt

BEND T A B

GASKET TAB CONTACTING

HEAD

OF

PIN, WITH

FULL WEIGHT

OF

FLOAT

COMPRESSING INLET

VALVE SPRING.

FIGURE

7b. FLOAT LEVEL ADJUSTMENT SPEC B-G

16

MAINFUEL

ADJUSTMENT

FS-1002

FIGURE 7d.

DOWNDRAFT CARBURETOR ADJUSTMENT

2.

Start the engine and allow it to warm up thoroughly (at least

10 minutes).


3.

Push

in on governor arm to slow engine down to about 400 to 500 rpm.

4, Release

governor

arm

allowing

engine to accel-

erate. If engine accelerates evenly and without hesitation, main fuel adjustment is correct. If it does not, turn the main adjustment

screw

out in

1/8 turn increments until the engine accelerates smoothly, but do not turn it out morethan 1/2 turn beyond the original setting.

5. Push in

on

governor arm to slow engine down to about

400-500 rpm. Turn the idle adjustment screw in until engine speed drops and then out until engine speed drops again. Over a narrow range between these two settings, engine speed

will

be at its maximum. Set the idle adjustment screw about 1/8 turn outward from the midpoint of this range.

MINIMUM

FLOAT DROP

0.20 INCH

FUEL LEVEL

0.25 INCH

NO FUEL

BEND FLOAT ARM

/

HERETO ADJUST

Float Adjustment

Turn carburetor and check float setting (see Figure

7e). The float should be a specific distance from the machined mating surface (without gasket). Bend the float

level.

float drop.

Bend the float arm as required to adjust

When checking float level and float drop, measure to float body, not seam.

FS-1524

FIGURE

7e.

FLOAT DROP ADJUSTMENTS

ADJUSTMENT BEGIN SPEC

NEEDLE

AND SEAT

,

CARBU~ETOR

BODY

FLOAT LEVEL ADJUSTMENT

BEND FLOAT

TAB HERE

TO ADJUST

0.02

WALBRO

f

0.02

INCH

17


CARBURETOROVERHAUL

Carburetion problems that are not corrected by mixture or float adjustments are usually a result

of

gummed-up fuel passages or worn internal parts. The most effective solution is a complete carburetor overhaul.

In general, overhauling a carburetor consists of complete disassembly, a thorough cleaning, and replacement of worn parts. Carburetor repair kits are available that supply new gaskets and replacements for those parts most subject to wear.

THROTTLE

SHAFT

AND LEVER

-

B

CHOKE PLATE

General instructions for overhauling a carburetorare 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 procedures involved. Carburetor components are

shown in Figures 8 and 8a.

THR

IDLE ADJUSTMENT

NEEDLE

A a

THROlTLE PLATE

T

Ignition

of

fuelmight cause serious explosion.

Do

personal injury or death by fire or not permit any flame, cigareffe, or other igniter near the fuel system.

FIGURE 8. DOWNDRAFT LUA CARBURETOR ASSEMBLY

Removal and Disassembly

1.

Disconnect all lines, linkages, wires, and attaching nuts or bolts; then, remove the carburetor from the engine. (Downdraft carburetors may require removal of the intake manifold to disconnect.)

Carefully note position

of

float assembly parts, then slide out retaining pin and remove the float assembly, any springs or clips, and the needle valve.

Unscrew and remove needle valve seat.

2.

Remove air cleaner adapter, if so equipped, and automatic choking assembly.

3.

Remove throttle and choke plate retaining screws, then plates. Pull out throttle and choke shafts, being careful not to damage the teflon coating applied to some throttle shafts.

Cleaning and Repair

1.

Soak all metal components not replaced by repair kit in carburetor cleaner. Do not soak non-metal floats or other non-metal parts. Follow the cleaner manufacturer's recommendations.

4.

Remove main and idle mixturescrew assemblies.

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.

5.

On downdraft carburetors, remove attaching screws and separate upper and lower carburetor sections. On sidedraft models, unscrew the retaining screw and remove fuel bowl from the upper carburetor body.

18

3.

Blow out all passages with compressed air. Avoid using wire or other objects for cleaning that may increase the size of critical passages.


IDLE

ADJUSTMENT NEEDLE

Bo

CHOKE SHAFT

HROTTLE PLATE

- S F L O A T

AXLE

Yl

ll!$

POSITION

HOOK

NDER TANG ON

FLOAT

SPRING

FLOAT

ASS EM

B LY

FUEL BOWL

I

MAIN JET

ADJUSTMENT

POSITION O F SPRING

AFTER INSTALLATION

FIGURE 8 a SIDEDRAFT CARBURETOR ASSEMBLY

4.

Check the condition of any needle valve not included in repair kit and replace if damaged

(Figure 8b). Replace float if loaded with fuel

or

damaged.

5.

Checkthechokeand throttleshafts forexcessive play in their bore, and replace if necessary.

6. Replace old components with new parts included in repair kit.

FIGURE 8b. MIXTURE NEEDLE INSPECTION

Reassembly and Installation

1. Install needle valve and seat, fuel bowl gasket, and float assembly. Make sure that all clips and springs are properly placed and that the float moves freely without binding. Check float level and adjust as necessary (see

Float Level

Adjust-

ment).

19

.

2.

Rejoin upper and lower carburetor sections on downdraft carburetors

- carburetor body on sidedraft models. n

severe personal injury or death. Use ;are when reassembling carburetor.

All parts must align perfectly or carburetor will leak fuel.

The float spring on Zenith sidedrafl carburetors rides on the inner face

of

the fuel bowl. Be sure to catch the end

of

the spring when reinstalling the bowl (Figure Sa).

3. Slide in throttle shaft and install throttle plate, using new screws if furnished in repair kit. Before tightening the screws, the plate must be centered in the bore.

To

do

so,

back

off

the throttle stop screw as necessary and completely close the throttle lever. Seat the plate by tapping with small screwdriver, then tighten screws. Install the choke shaft and plate in the same manner.

4.

Install main and idle mixture screw assemblies.

Turn in screws until lightly seated and then out the number of turns specified.

Forcing the mixture adjustment screws tight will damage the needle andseat. Turn in only untillight tension is felt.

5.

Reinstall carburetor on engine and connect fuel lines, linkages, and wires.

6. Reset mixture screws according to directions given earlier in this section. Install air cleaner adapter, where used, and air cleaner.


FUEL

PUMP TEST

Test the fuel pump by checking the pump outlet pressure. Use the following procedure.

1. Remove the fuel line from the pump outlet and install a pressure gauge.

2. Press the START switch and hold it for several seconds until pressure reading is constant.

3. Pressure reading should be 2-112 to 3-1/4 psi

(17.2 to 22.4 kPa). If the retension is good, the pressure should stay constant or drop off very slowly.

A

low pressure reading with little or no pressure drop indicates a weak or broken diaphragm or diaphragm spring, worn linkage or leaky check valves. If pressure is above maximum, the pump diaphragm is too tight or the diaphragm (or plunger) return spring

is

too strong. Any of the above conditions are cause for repair or replacement

of

the pump.

PUMP ASSEMBLY

I

1

%

1

GASKET

1

COVER

FS-1487

FIGURE 9. REMOVAL OF MAGNET AND FILTER

PUMP ASSEMBLY

PLUNGER

WASHER

ELECTRIC FUEL

PUMP

FS-1486

FIGURE 9a. REMOVAL OF PLUNGER ASSEMBLY

The Facet and Bendix pumps incorporate a hollow stainless steel plunger in a brass cylinder. The plunger has no gland or seal, but is freely fitted. The fluid being pumped provides the seal by filling the small clearance between the plunger and cylinder. Energiz- ing the pump's electric solenoid pulls the plunger downward, compressing the return spring. When the solenoid is de-energized, the return spring drives the plunger back, delivering fuel to the pump outlet.

DO not substitute automotive type electric fuel pumps for sfandard

Onan supplied electric pumps. The output pressure is much higher and can cause carburetor flooding or fuel leakage, creating a fire hazard.

Fuel

Pump Repair

Service of the Facet pump is limited to the bottom cover, filter, plunger tube, and plunger assembly.

All

parts

of

the electric system are hermetically sealed

in

a gas atmosphere and are not serviceable. If electrical failure occurs, replace the pump.

L z z 2

Do not tamper with the seal at the center of the mounting bracket on the side of the pump as it retains the dry gas which surrounds the electrical system. Electrical system components are not serviceable.

Use the following procedure for servicing the pump:

1. Using a5/8-inch wrench, loosen, the pump cover, then remove by hand.

2.

Remove the filter, magnet and cover gasket (Fig- ure 9).

20

3.

Using a thin nose pliers, remove the retainer spring from the plungertube. Removethewasher,

O-ring seal, cup valve, plunger spring and plunger from tube (Figure sa).

4.

Wash all parts (except gasket and seal) in parts cleaning solvent, Blow out solvent and dirt with low pressure compressed air. Slosh the pump assembly in cleaning solvent, blow dry and swab the inside of the plungertube with a cloth wrapped around astick. If the plunger does not wash clean or has rough spots, gently clean the surface with crocus cloth.

Most parts cleaning solvents are flammable

and

could cause serious personnel injury if used improperly. Fol- low the manufacturer's recommendations when cleaning parts.

5.

Insert plunger in tube, buffer spring end first.

Check fit by slowly sliding the plunger back and forth in the tube. It should move fully without any tendency tostick. If aclick cannot be heard as the plunger

is

slid from one end to the other, the internal pump assembly is not functioning properly and the pump should be replaced.

6.

Install plunger spring, cup valve, O-ring seal and washer. Compress the spring and install the retainer with ends in the side holes of the tube.

7.

Check cover gasket and replace if deteriorated.

Place cover gasket and magnet in the bottom cover and install filter and cover assembly on pump. Twist cover on by hand and tighten securely with a 5/8-inch wrench.


MECHANICAL

FUEL

PUMP

(Spec A-E)

A

diaphragm type fuel pump is used. If fuel does not reach carburetor, check the fuel pump. Be sure there is fuel in the tank.

If line is open and no fuel comes through, pump isdefective. Failureof pump isusually due to a leaking diaphragm valve or valve gasket, a weak or broken spring, or wear in the drive linkage.

Oil diluted with gasoline may indicate a faulty diaphragm.

VALVE.GASKET-

VALVE

CAGE

RETAINER

Removal

1.

Remove the fuel inlet and outlet lines from the pump.

2. Remove the two capscrews holding the pump to the engine.

3. Remove the pump, spacer (if used) and gasket from the engine and discard the gasket.

DIAPHRAGM ASSEMBLY

MOUNTING GASKET

LOWER

SIDE

APHRAGMGASK

ROCKER ARM LIN

Installation

1.

Remove all gasket material from mounting faces and spacer (if used). Apply oil-resistant sealer to both sides of the gasket(s) and to the threads of the attaching capscrews.

2.

Place the gasket (and spacer if used) on the mounting face of the pump. Slide the mounting capscrews through the pump and gasket (and spacer) to prevent the gasket from slipping out of place.

3. Lightly place the pump in position on the engine, making sure the rocker arm is riding on the camshaft lobe. Start both capscrews and check for proper gasket placement. Alternately torque capscrews to specifications.

4.

Connect the fuel inlet and outlet lines.

5. Operate the engine and check for leaks.

Repair

Repair kits are available that provide replacement parts for the pump which are most subject to wear.

Use all parts included in the repair kit. Proceed as follows:

1.

After the pump is removed from the engine, scribealineon the flangesofthe upperand lower pump bodies to assure correct positioning when reassembling.

2.

Remove the securing screws and separate the upper and lower pump bodies.

3.

Detach the valve cage retainer from the pump upper body. Noting their position, remove the valve and cage assemblies and their gasketsfrom the retainer (Figure 9b).

FIGURE 9b. EXPLODED VIEW

OF

PUMP

21

4.

Detach the pump diaphragm by pressing its metal base into the pump body and turning it 1/4 turn.

(Figure 9b).

5.

The rocker arm return spring can normally be removed without removal of the rocker arm from the pump body. Use a small screwdriver or tweezers to compress the spring and tip it

off

the rocker arm catch. When installing the new spring, make sure it is properly placed before remount- ing the pump.

6. Clean in solvent all pump parts that will not be replaced and allow to dry.

7.

Install the new valve and cage assemblies and their gaskets in the retainer. Be sure the assemblies are in proper position and fullyseated. Rein- stall the retainer and assemblies in the pump upper body.

8.

To

install the new pump diaphragm, turn the pump lower body upside-down and place the diaphragm and spring in the body. Pressthe base of the diaphragm up into the body of the pump and turn 1/4 turn.

9. Install new rocker arm return spring. Check for proper spring placement.


10. Place the upper and lower bodies of the pump together with the scribe marks aligned. Start the four securing screws, making sure they do not chew into the diaphragm fabric. Leavethe screws

2 Or

FUEL FILTER

(Begin Spec

F)

Electric pumps incorporate a filter within the casing of the pump (Figure loa). Use

a

5/8 inch wrench to twist

off

the bottom of the pump and remove the filter element. If the filter is dirty, replace it along with the cover gasket.

11 Operate the rocker arm several times to flex the new diaphragm. While holding the rocker arm fully flexed, tighten the body screws.

I",?

fq

Failure to flex the rocker arm

fully

while tightening the pump bodies together will result in excessive pump pressure and possible engine flooding or pump diaphragm failure.

LECTRIC FUEL

FUEL FILTER

(Spec

A-E)

Periodic maintenance should consist of cleaning the fuel filter, flame arrestor, carburetor, and complete carburetor adjustment.

Remove fuel sediment bowl, empty, clean, and dry

(Figure 10). Remove screen and clean any trapped

particles. When replacing the sediment bowl, besure screen and gasket are in place.

FS-1488

FIGURE loa.

BENDIX AND FACET ELECTRIC PUMP FILTER

FIGURE 10. FUEL FILTER

AUTOMATIC CHOKES

Automatic chokes may occasionally require

adjust-

ment to provide the best fuel-to-air mixture for the existing temperatureconditions. Several adjustments may be necessary to arrive at the correct setting. Let the engine cool to ambient air temperature between each adjustment.

22

If theenginestarts, runsforafew minutes, then stops, the choke mixture may be too lean. If the engine starts, but runs

rough

and is sluggish once

it

has warmed up, the choke mixture may be

too

rich.


AMBIENT TEMP.

( O F )

CHOKE OPENING (Inches)

CHOKE OPENING

60

65

1/8

70

75

80

85 90

95 100

9/64 5/32

11/64

3/16 r3/64 7/32

15/64 1/4

-G

GZ-

LOOSEN THIS

SCRW AND

ROTATE THE

ENTIRE COVER

ASSEMBLY

8 6 4

FIGURE 11. THERMO-MAGNETIC CHOKE SETTINGS

AND

Thermo-Magnetic Chokes (Spec A-G)

Thermo-magnetic chokes have a strip-type heating

element attached directly to a bi-metal coil (Figure

11

a). As the element heats, the coil twists and gradu- ally opens the choke valve. An electromagnetic solenoid pulls the coil

in

tighter during engine starting to increase the choking effect. The coil is calibrated to provide the correct choke setting under various temperature conditions.

Adjustment Adjustment of the choke setting must be made with the engine cold. Do not attempt adjustment until the engine has been shut down for at least

an hour. Refer to Figures 11 and 11 a and proceed as

follows:

1. Loosen the screw which secures the choke body assern bly.

2. Rotate the choke body until the correct choke

setting is attained. Figure

11,

lists the correct settings for various temperature conditions.

3. Start the engine and observe its operation. Slight readjustment

of

the choke setting may be necessary for best engine operation.

4-

Retighten the securing screw when adjustment

has

been completed.

A876

THERMO-MAGNETIC

CHOKE NUT (5/16- 18”)

‘

-WASHER

>

(24/64

I.D.

x 9/16

O.D.

x

1/16 ”)

FIGURE l l a . THERMO-MAGNETIC CHOKE ASSEMBLY


23

COVER

Repair:

If choke will not heat properly, check for broken heater wire, high-resistance connections, or broken lead wires to the bi-metal and heater assembly. With the element at room temperature, check the heater resistance with an ohmmeter. The resistance should be about 30.6 to 37.4 ohms for a 12 volt system. If the heater is defective, replace it with a new one. When the start button is engaged, the solenoid should cause the spring-loaded armature to contact the solenoid core.

If this does not occur, check for broken lead wiresora defective solenoid coil. There must be slack in the lead wires between the choke body and the bi-metal

' and heater assembly. The solenoid coil resistance should be 2.09 to 2.31 ohms in a 12 volt system.

When replacing the cover on the thermostat and heater assembly, be certain that the choke heater lead wires have been correctly installed in the choke housing. Improper replacement of the lead wires can cause the choke assembly to malfunction.

'

The wires enter the choke assembly through a small notch that is cut in the edge of the housing. A cover holds the wires in place and prevents movement when tightened. When properly installed, the lead wires will hang freely underthe bi-metal coil when the choke is in either the open or closed position. The end of the heater wire sleeve should be located from

1/8 inch inside the choke housing to flush with the inside wall.

When assembling the thermomagnetic choke, the bi-metal and heater assembly is connected as follows:

1. Lead tagged solenoid

.

G

goes to ground terminal on coil

2. Lead tagged

H

goes to either H1 terminal on solenoid core.

CATCH OUTER END

OF COIL IN SLOT

IN COVER TAB

ELECTRIC CHOKE

WARNlNG

The choke consists of a bi-metal coil and an electric heating element. The bi-metal coil connects to the choke shaft and holds the choke plate nearly closed when the engine is cold.

As theenginestarts, current is supplied to the electric heating element in the choke cover. Heat from the element causes the bi-metal coil to twist. The twisting

-

ing normal operation and can cause

The choke cover gets very hot dur- serious burns

i f

touched.

Do not touch the choke cover while the engine is operating.

If

the engine starts but runs roughly and blows out black smoke after a minute or two of operation, the choke is set too rich. If the engine starts but sputters or stops before it warms up, the choke is set too lean.

Adjustment:

Table 2 lists average choke settings.

Loosen the two mounting screws and rotate the choke cover until the correct setting is attained.

Check the setting by starting the engine and observ- ing its operation. Be sure to retighten the mounting screws after adjustment

(See

Figure 12).

TABLE 2. CHOKE SPECIFICATIONS

I

L

AVERAGE CHOKE SETTING

AMBIENT TEMP

I

CHOKE OPENING

40"

F

4 . 4 O c

70'

F

21°C

I

7/32 to 9/32 inch

5.6 to

7.1

rnm

I

11/32 to 13/32 inch

8.9

to 10.4 mm

I

I

I

'

THIS

WAY

FOR

RICHER

MIXTURE

MOUNTING SCREWS

INSERT INNER END

OF COIL IN SLOT

IN SHAFT

FS

1484

' FOR

LEANER

MIXTURE

A

i

LOOSEN THESE

SCREWS

A N D

ROTATE THE

ENTIRE COVER

ASSEMBLY

CHOKE PLATE

MEASURE CHOKE SETTING

HERE

FIGURE

12. ELECTRIC CHOKE ADJUSTMENT

24


Repair: If

the choke fails

to

operate, check to see if the heating element is working. If it is, the choke cover should become hot after a few minutes

of

engine operation.

If

the cover

does

not get

hot,

check for current at the cover terminal. The engine must be running. Trace down any opens or shorts.

Remove the choke cover to inspect the heating element and

coil.

Seethat the element

is

not burned out or broken. The bi-metal coil must not be damaged, dragging in the housing,

or

have an improperly directed spiral.

When installing a new coil, maintain the original direction

of

spiral inward from the fastening screw.

Besurethe coil setssquarely in the housing so itwill not bind. Coil should not touch inside

of

choke body.

.

.

.

25


FIXED

SPEED GOVERNOR

Before making governor adjustment, run, the engine about 10 minutes to reach normal operating temperature. Be sure carburetor load and idle needles are properly adjusted before checking or adjusting governor system. For an accurate governor adjustment, a reliable tachometer is required.

Confacf

with

rotating machinery mighf cause serious personal injury or death. Sfay clear of rofafing components and ensure

fhaf

protective shields andguards are

in

place and secured before operafing machinery.

Besureto clean, check, and lubricategoveror linkage

(steel ball joints) before making any adjustments.

Binding in the linkage joints can cause erratic operation. Some early models used plastic ball joints which require no lubrication.

If the following checks do not remedy erratic operation, install a new governor spring. Springs become fatigued with age.

Governor and vacuum booster control engine speed

(Figure 13). Rated speed and voltage appear

on

nameplate. On

a

4

pole generator engine speed divided by 30 equals frequency.

.

. r

THROTTLE

STOP SCREW

INTERNAL SPRING

BRACKET

THIS DISTANCE

1/32

INCH

AT

NO LOAD

CARBURETOR

THROTTLE ARM

CARBURETOR

THROTTLE ARM

CARBURETOR

THROTTLE

THIS

DISTANCE

DETERMINES

SENSITIVITY

VACUUM

BOOSTER

GOVERNOR LINKAGE

JOINT

RING BRACKET

ADJUSTING STUD

ADJUSTMENT

FIGURE 13. GOVERNOR AND GOVERNOR ADJUSTMENTS

26


*

Thus,

1800 rprn gives a

60 hertz frequency, and

1500 rprn gives

50 hertz frequency.

Preferred speed varies approximately

3

hertz from no-load to full-load operation. Be sure throttle, linkage, and governor mechanism operate smoothly.

Linkage

The engine starts at wide open throttle. Length of linkage connecting governor arm to throttle arm is adjusted by rotating the ball joint. Adjust length so that with engine stopped and with tension on gover- nor spring, the stop screw on carburetor throttle lever is 1/32 inch from the stop pin. This setting allows immediate control by the governor after starting, and synchronizes travel of governor arm and throttle

shaft. See Figure 13.

Vacuum-Booster Adjustment

1.

After sensitivity adjustment, connect booster external spring to slide on governor link (Figure

13a).

2. With engine running at no-load, move adjustable slide to point where there is no tension on spring.

3. Apply full-rated load to engine.

4.

If

speed increases more than at no-load, lessen internal spring tension of the booster. To change tension, pull out spring bracket and move the pin toadifferent hole (Figure 13a). If speed decreases when load is applied, increase internal spring tension of the booster.

VACUUM

BOOSTER

Speed Adjustment

1.

Start engine and allow to warm up without load. n

of exhaust gases injury

or

death. Be sure deadly exhaust gas is piped outside and away from windows,

doors

or

other inlefs to building.

2.

Remove vacuum booster external spring from

bracket slide on the governor link (Figure 13).

3.

Refer to voltage and speed charts. If needed, increase speed by increasing tension on the governor spring. Decrease tension on the governor spring to reduce speed.

4.

Add a full-rated load to the engine and compare lower speed and voltage with those shown in the charts. If operation does not remain within these limits, check governor linkage and governor spring, and, if necessary, follow preceding procedure again.

5.

Check and, if necessary, adjust governor sensitivity (see

Sensitivity

Adjustment).

Sensitivity Adjustment

1.

Start engine and allow to warm up.

2.

Check voltage and speed, first without load and then with a full load. See voltage and speed charts.

3. Increasesensitivity (closer regulation) by shifting

adjusting clip toward governor shaft (Figure 13).

Move clip away from governor shaft to decrease sensitivity.

Too much sensitivity causes engine to hunt.Toolittlesensitiv- ity results in too much speed difference between no-load and full-load conditions.

4.

A change in sensitivity adjustment usually requires a compensating speed adjustment (spring tension). Then proceed to vacuum booster adjustment.

EXTERNAL

SPRING

FIGURE 13a. VACUUM BOOSTER

SPEED CHART FOR

CHECKING GOVERNOR REGULATION

AC GENERATING SETS

Maximum No-Load Speed

RPM

Frequency

(Hz)

Minimum Full-Load Speed

(Without Booster)

RPM

Frequency (Hz)

60 HERTZ

1890 1560

I

63

I

52

I

1770

59

50 HERTZ

1490

49

VOLTAGE CHART FOR

CHECKING GOVERNOR REGULATION

AC GENERATING SETS

120 VOLT

(1 PH . 2

W)

OR

1201240 V

(1 PH.

2W)

OR

(1 PH. W) (3 PH. 3W)

126 252

Maximum No-Load Volts

Minimum Full-Load

Volts

(Without Booster) 110

,

220

27


Ignition System

The engine

is

equipped with an automotive type battery ignition system. Both spark plugs fire simultaneously, thus the need for a distributor is eliminated.

The major components of the ignition system are: the spark plugs, coil, breaker points and condenser. The

MCCK ignition system is shielded to prevent radio interference.

IGNITION COIL

To test primary and secondary windings within the ignition coil proceed as follows:

1. Use a Simpson 260 VOM or equivalent.

2. Place black lead on ground (-)terminal of coil and red lead to positive (+) terminal. Primary resistance should read:

RCCK 3.87-4.73 ohms

MCCK 1 .OO--1.10 ohms.

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

(Figure 14). Secondary resistance should read:

RCCK 12,600-15,400 ohms

MCCK 10,800-13,200 ohms.

3.

Removetwo mounting screws (A) and pull points out

of

box just far enough

so

screw B can be

removed. See Figure 15. Replace points with a

new set but do not completely tighten mounting screws (A).

4. Rotate crankshaft clockwise (facing flywheel) by hand until points are fully open. Turn screw

(C)

until point gap measures 0.020 inch (0.51 mm) with a flat thickness gauge.

5. lighten mounting screws and recheck gap.

6.

Proceed to lgnition

Timing.

Each time new breaker points are installed, placea drop of oil on the breaker arm pivot.

*

PLACE DROP

O F

OIL ON PIVOT POINT

WHENEVER NEW POINTS ARE

INSTALLED.

REFERENCE MARK)’

FOR

---

’LOOSEN SCREWS

-AND

SHIFT

BOX-

20

ADVAVCE

OR--

FIGURE 14. TESTING IGNITION COIL

4. If any of the above conditions are not met, replace coil. Refer to PARTS CATALOG for correct part number.

BREAKER POINTS

The timing is adjusted during initial engine assembly and is fixed bythe point gap adjustment.

To

maintain maximum engine efficiency, change the breaker points every 200 hours of operation.

1.

Remove two screws and cover on breaker box.

2. Remove both spark plugsso engine can beeasily rotated by hand. If plugs have not been changed within last 100 hours, replacethem with new ones after setting breaker points.

28

FIGURE 15. IGNITION TIMING

IGNITION TIMING

Ignition Timing

-

Always check timing after replacing ignition points or if noticing poor engine performance. Proceed as follows:

1.

To check ignition timing accurately, use a timing light when engine is running. Connect timing light according to manufacturer’s instructions.

Either spark plug can be used as they fire simultaneously.


2.

Place a white chalk or paint mark on flywheel

TC mark.

3.

Start engine and check timing. The TC on flywheel should line

up

with correct timing mark

(20'BTC).

4.

If timing needs adjustment, loosen breaker box mountings screws and move left to advance or right to retard timing (when facing rear of engine).

5.

Be sure mark on flywheel lines up with correct timing mark.

6. Replace breaker ware removed.

box

cover and any other hard-

3.

Lamp should go out just as points open (20" and ignition occurs. Timing marks should align.

4.

If timing needs adjustment, loosen mounting screws on breaker

box

and move left to advance or right to retard timing (when facing rear of engine).

SPARK PLUGS

Check, and regap spark plugs every 100 hours

of

operation (Figure 16). Replacespark plugs that show

signs of fouling or electrode erosion.

Ignition Timing

-

1.

Connect a continuity test lamp set across ignition breaker points. Touch one test prod to breaker

box

terminal to which the coil lead is connected and touch other test prod to a good ground on engine.

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

FIGURE

16.

SPARK PLUG GAP

29


Battery Charging System

BATTERYCARE

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

77°F (25OC).

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. After making connections, coat the terminals with a light application of petro- leum jelly or grease to retard corrosion.

Poor contact at the battery cable connections is oflen 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

i

Do not smoke while servicing batteries.

BATTERY CHARGING, ALTERNATORS

The flywheel alternator is a permanent magnet alternator and uses

asolid-state voltage

regulator-rectifier

for controlling output. Figures 17 and 18.

Weak ignition spark or a discharged battery indicate trouble

in

the charging system. But before testing the charging system, always check the battery for service- ability.

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

1. Be sure output control plug (connector)

is

in- serted properly. The plug must bottom in recept- acle-eliminates any resistance due to a poor connection. Keep clean and tight.

2. Make sure alternator stator leads are not shorted together.

3.

Be sure regulator-rectifier output control has a good ground connection. Mating surface for mounting must be clean and fasteners tightened properly.

4.

Never reverse the battery leads.

Charging system tests require a fully charged battery.

'

15

AMP FLYWHEEL ALTERNATOR

SYSTEM

The 15 amp system has two white wires coming from stator and is used on 3600 rpm engines. See Figure

17.

VOLTAGE

REGULATO

RECTIFIER

MOUNTED ON

CYLINDER COVER

\

\

MOUNTED BEHIND

BLOWER WHEEL

VR1

VOLT

REG

RECT

AC

B+

AC

TOR

PRESSED INTO

FLYWHEEL

(NOT REMOVABLE)

TO

BATTERY

CAUTION:

REGULATOR MUST BE GROUNDED

THROUGH MOUNTING BOLTS

ES-1332

FIGURE 17. 15

AMP

30


TESTING PHELON

15

AMP SYSTEM

BASIC TEST

1. Battery

2. Regulator

PROCEDURE

Battery Voltage

- unit not running.

Battery Voltage after unit is running

3 to 5 minutes.

TEST VALUES

12 VDC

I

3. Alternator Stator and Wiring

4. Alternator and

Wiring

Ohmmeter reading from stator output, unit not running. Check at plug.

13.6 to

14.7

__

I

Measure AC open circuit stator voltage with unit running. Measure between two 28 VAC minimum stator leads with plug disconnected and 65 VAC maximum unit running at approximately 3600 rpm.

I

1

.

-

. .

..

.

.

20 AMP FLYWHEEL ALTERNATOR

SYSTEM

The 20 amp flywheel alternator systems use a separ-

ate regulator and a separate rectifier. Figure 18. Two

black wires and one red wire come from the stator assern bly.

FIGURE 18. 20 AMP

31

ALTERNATOR STATOR

MOUNTED BEHIND BLOWER WHEEL

RECTIFIER

ASS€

MB LY

\

,

*

,

pMToR

ASSEMBLY


TESTING ALTERNATOR

For tesfing this system, use a voltmeter-ohmmeter such

as

a Simpson 270. Listed below are various alternator problems with individual test procedures following.

No

Output

-

Stator Assembly

Examine 1ead.wires for loose or broken connections at the regutator and rectifier. Use the

Rxl

scale on the ohmmeter for detecting opens in the stator. Dis- connect the three wires that come from alternator stator (two black, one red). Connect ohmmeter test leads to red leadwire and ground to check continuity.

The ohmmeter reading should be about 2.0-ohms.

See Figure 18.

Next connect meter to black leadwires and ground.

Approximately 0.1-ohm should be read from either black lead to ground. If noconnection existsbetween' ground and black leads, stator assembly should be replaced.

Checking Rectifier Assembly

Examine each of the two diodes for breakdown by connecting. ohmmeter (Rxl scale) to one black lead and to the white lead. Meter should read 10-ohms

in

proper polarity. A shorted diode would readzero resistance and would cause a short circuit through the lead winding when in operation. An open diode would read infinite in both directions, indicating that replacement is necessary.

TESTING

REGULATOR ASSEMBLY

To check for proper voltage regulation, attach a DC voltmeter to battery and operate engine at approximately

I800

rpm. Battery voltage will climb to the present factory setting (14.2 to 14.8 volts).

.

Some installations may vary due to voltage drop in the length of ammeter harnesses. Other variations may stem from a loose connector in the harness or loose or corroded battery leads. LOW voltage readings at the battery mean poor battery connections.

To

test regulator, remove connector. Using the

Rx10,OOO scale of the ohmmeter, connect one meter lead to red leadwire arid other meter lead to regulator

base. See Figure 18.

No

deflection should be noted on the ohmmeter

in

either polarity. Next connect meter to black leadwire and base of regulator. Meter will deflect fuily in one polarity, with no deflection in the other.

Full Charge

-

Will

Not Regulate

Check for broken leads at connection to regulator plates.

To

be sure regulator winding operates proper-

ly,

connect red lead to ground and start engine. A maximum of

4

amperes should be noted. This would indicate stator winding is satisfactory.

If so,

replace regulator.

No Charge

If alternator does not charge when load is applied to battery, shut off engine and disconnect one red leadwire from regulator terminal. Be sure lead is taped or isolated from conducting engine

parts.

Once again, start engine. Alternator should charge

to

full output; if it doesn't, replace stator assembly.

TESTING 20 AMP SYSTEM

TEST

VALUE

Battery voltaye

- unit not running.

12 Volts

DC

I

Battery voltage with unit running at 1800 rpm or more.

1

14.2

-

14.8

Volts DC

'

I

AC voltage from stator with plug disconnected and unit running at approximately 1800 rpm.

.

23

VAC minimum'

Black to Black

Ohmmeter reading at plug when checking two AC stator leads

- unit not running.

0.5 to 0.7-Ohms"

Black to Black

* *

-

-

48 VAC maximum at 3600 rpm, Red to Ground.

-

Resistance values (Ohms) are as follows between wire pairs.


32

Oil System

I

*

The engine has pressure lubrication to all working parts. The oil system includes:

Oil intake cup

Gear type oil pump

Oil pressure gauge

Oil passages to deliver oil throughout. engine

Oil

filter (if used)

Crankcase pressure could blow out

-

burns. Do

NOT

check oil while the engine

is

operating.

The oil pump is located on the front surface of the crankcase and is driven by the crank gear. The inlet pipeand screen assembly attach directlytothe pump

body. Figure 19. A discharge passage in the cover of

the pump registers

with

a drilled passage in the crankcase. Parallel passages distributeoil to the front main bearing, rear main bearing, and pressure control bypass valve.

Circumferential grooves in the main bearings supply oil to the connecting rod bearings through drilled passages from each main journal.

A

drilled passage connects the front main bearing oil supply to the front camshaft bearing. The flyball governor is lubricated byadrilled passage in thefront camshaft journal.

The

oil

overflow from the bypass valve furnishes lubrication to the camshaft drive gears.

Normal oil pressure should be 30 psi (207 kPa) or higher when the engine isatoperating temperature.

I f

pressure drops below 30 psi

(207

kPa) at governed speed, inspect the oil system for faulty components.

_ _

OIL

PUMP

INTAKE CU

ON

LEFT

SIDE

+

OIL

PUMP

ASSEMBLY;

FIGURE 19. OIL PRESSURE PUMP ASSEMBLY

OIL BYPASS VALVE

The by-pass valve (located to the right and behind gear cover), controls oil pressure by allowing excess oil to flow directly back to the crankcase. Normally the valve begins to open about 30 psi (207 kPa).

The valve is non-adjustable and normally needs

no

maintenance.

To

determine if abnormal (high or low) oil pressure is caused by a sticky plunger inspect as f

01 lows:

1.

Remove 3/8 x 24

x

3/4 cap screw located behind gear cover and under governor arm.

2.

Remove spring end plunger with a magnet tool.

Clean plunger and spring with

a

suitable solvent and install.

FIGURE 20.

33


CRANKCASE BREATHER RCCK

AND MCCK (Begin Spec

B)

These engines areequipped with a crankcase breather for maintaining crankcase vacuum. Clean the crankcase breather cap and valve assembly and the breather tube baffle in a suitable solvent every 300 operational hours.

To

assembly, remove breather hose clamp and breather

tube clamp. See Figure 21.

CRANKCASEBREATHERMCCK

(Spec A Only)

Lift off rubber breather cap. Carefully pry valve from cap. Otherwise, press hard with both of your thumbs on top of cap and keep fingers below to release valve from rubber cap. Wash this fabric, flapper-type check valve in a suitable solvent.

Dry

and install. Position perforated disc.toward engine. See Figure 22.

1

SREATHER HOSE

.AMF

B R E A T H E R T U B E

CAP'

F L A P P E R

V A L V E

ASSEMBLY

125i

BREATHER.

U B E B A F F L E

FIGURE 21. CRANKCASE BREATHER FIGURE

22. CRANKCASE BREATHER MCCK SPEC A ONLY

34


RCCK Cooling System

.C

'

DESCRIPTION

The RCCK cooling system is a closed system which uses an engine mounted pump to draw and circulate coolant through the engine and radiator.

Water from the radiator enters the pump located on the front 0ftheengine.Thepumpdelivers waterto the cylinder jacket and it flows through thejacket'and out of the cylinder heads to the radiator. The waterflow

is

controlled by thermostats. For engine warm-up, with thermostats closed, a by-pass between the cylinder heads allows water flow.

MAINTENANCE

Cooling system maintenance includes periodic inspection for leaks, and flushing and cleaning.

FLUSHING

The cooling system must be kept clean to function properly. Scale reduces heat transfer and restricts water flow. Flush the system at least once a year and more often if operation indicates clogged passages, pump wear, or overheating.

23. Attach a flushing gun nozzle to the thermostat

opening and fill the block with water; then apply air pressure. Repeatthe process until watercoming from the block is clean.

CLEANING

To clean the cooling system, drain and fill with radiator cleaner. When chemical cleaning is done, always flush the cooling system to wash out deposits loosened by the chemical cleaning. Flush the engine water jacket as previously discussed. When flushing is completed, check the system thoroughlyfor leaks.

REPAIR

When making cooling system repairs, use Permatex

or

other thread-sealing compound on all threaded connections.

All water lines should be 1/2 inch (13 mm) inside diameter or larger. Long runs of pipe or hose need a larger inside diameter to reduce resistance.

Water Pump: Refer to centrifugal pump repair in

MCCK COOLING SYSTEM

for repair procedures.

Thermostats: A thermostat is located on the top of each cylinder head. Replace thermostats that are damaged from corrosion or other causes.

Check opening and closing by placing the thermostat and a thermometer in heated water. The thermostat should start to open at 175"

F

(70' C) and be full yopen at 202' F (94OC).

It should close immediately when removed from hot water. Replace the thermostat if it does not operate properly.

High

Water Temperature Cut-off Switch: This nor-

mally closed switch (Figure 24)

senses water temperature in the engine cooling jacket. The switch opens, breaking the circuit to the coil primary when the water temperature reaches about 230" F (11

0"

C) and closes when the temperature drops below 190'

F

(88'C).

TEMPERATURE

SWITCH

'

FIGURE 23. THERMOSTAT REMOVAL

35

FIGURE

24. HIGH

WATER TEMPERATURE SWITCH


MCCK Cooling System

DESCR I PTI 0 N

The MCCK cooling system is a pressure type system which uses an engine mounted rubber impeller pump to draw and circulate raw water throughout the system.

In open type cooling systems, water enters the pump located on the front right side of engine. The pump delivers water to the cylinder jacket. Water flows through the jacket and out openings in cylinder heads controlled by thermostats.' For engine warm- up, with thermostats closed, a by-pass from the cylinder block to the thermostat allows water flow.

From thermostat, water passes through the water- cooled exhaust manifold and out engine cooling system.

MAINTENANCE

Cooling system maintenance includes periodic inspection for leaks, inspection of the rubber pump impeller, and flushing and cleaning. n

coolanf

mighf

result in serious burns.

Do

not bleed

hot,

pressurized coolant from a closed cooling sysfem.

The rubber impeller, because of continuous flexing, will, in time, need replacement. If impeller fails after short service (usually under'500 hours), check for possible defects, such as severe pitting or abrasion caused by dirt in the cooling system.

Cooling system MUST be kept clean to function properly. Scale reduces heat transfer and restricts water flow. Flush system at least once a year and more often if operation indicates clogged passages, pump wear, or overheating.

To flush engine, remove the thermostats, Figure 25

and the water pump cover. Partially restrict pump opening

so

the cylinder block fills with water. Attach a flushing gun nozzle to thermostat opening and fill block with water; then apply air pressure. Repeat the process until water coming from the block is clean.

TESTING

Cooling system can be tested for two abnormal conditions: (1) insufficient water flow and (2) air leaks.

1.

To

measure water flow, install a tank of known capacity at the water outlet. Run engine until the thermostat opens and then measure the length of time necessary to fill the tank. From this, obtain the flow in gallons per minute flow is below

3.5

GPM, check pump operation and inspect passages and water linesforclogging.

THERMOSTAT

As888

@-DRAIN PLUG

FIGURE

25. THERMOSTAT

REMOVAL

36

2.

Air leaks will cause premature impeller failure.To test for air leaks, insert the cooling system outlet into a tank of water and watch for bubbles while engine is operating. If bubbles appear, inspect cooling system thoroughly to find the source.

REPAIR

When making cooling system repairs, use Permatex or other thread-sealing compound on all threaded connections.

All water lines should be 1/2 inch or larger inside diameter. Long runs of pipe or hose need a larger inside diameter to reduce resistance.

THERMOSTATS

Thermostats are located on the top of each cylinder head. These are connected by tubing to the water- cooled manifold. Replace all thermostats that are damaged (from corrosion or other causes). See Fig-

ure

25.

Check opening and closing by placing thethermostat and a thermometer in a water bath. The thermostat should start to open at 145OF and be fully open at

165OF:

It should close immediately when removed from hot water. Replace the thermostat if it does not operate properly.


"

.

'

HIGH WATER TEMPERATURE

CUT-OFF SWITCH

This

normally

closed switch senses water ternpera-

ture in the engine cooling jacket. The switch opens, breaking the circuit to the coil primary when the closes when the temperaure drops below approximately 160"

F.

WATER PUMP

This pump is a positive displacement, neoprene impeller type, used to pump raw water through the cooling system.

Disassembly (Pump 131-0165)

1. Remove the pump end plate screws, end plate,

and gasket as shown in Figure

26

(Step a).

2. Pull out neoprene impeller with a pair of pliers

(Step b).

3. If further disassembly is required, disconnect the hoses and removethe two capscrews holding the pump to the engine (Step c). Lift pump from engine.

4.

Loosen the set screw on the side of the pump and tap it lightly to free the cam from the pump body.

Lift out cam and wear plate (Step d).

5. Remove the retaining ring (using a screwdriver) as shown in Step e and slide the seat assembly

(O-ring and ceramic seal) off the pump shaft.

6.

Pry the bellows assembly out of the pump body by inserting ascrewdriverthrough the drain slots

(Step f).

7. Drive the shaft and bearing assembly out of the pump body using a bearing driver or press. The bearing is press fit on the shaft and comes off in one integral part.

Assembly

(Pump

131-0165)

Inspect the pump housing for wear, rough surfaces,

or

pitting and replace if any of these conditions exist.

Replace any other

worn components

such

as bearings, seals, or impeller and use a new end plate gasket.

1.

Apply sealing compound to thesealing lip around the edge of the bellows seal. Place the bellows seal in the pump body and drive it into place(Step

9)

-

2.

Apply a small amount of Loctite or eqivalent on the outside surface of the bearing (Step h).

3. Place the bearing and shaft assembly in the pump bore and drive into place (Step i). Strike outer race only

to

avoid damage to pump shaft and bearing.

4. Lubricate both sides of the seat assembly (ceramic seal and O-ring) with lubricating oil and slide assembly over pump shaft.Theceramic portion of the seat assembly should contact the bellows. Compress the seat assembly against the bellows and at the same time push the retaining ring into its groove on the pump shaft.

5. Place wear plate and cam so notch in wear plate lines up with tank on cam (Step j). Fasten cam to housing with screw.

6.

Align the flat spot in the center of the impeller with the flat spot on the pump shaft. Bend back the impeller blades nearest the cam and push the impeller onto the shaft.

Do

coating of installing.

oil

from the new impeller before

7. Install the pump end plate using a new gasket and tighten end plate screws to 15-1 7 in-lb (1.7-1.9

Nm).

8.

Install pump on engine (Step k) and attach hoses.

37


BEARING AND

SHAFT ASSEMBLY

PUMP

BODY

ASSEMBLY ASSEMBLY

GASKET

END

PLATE

SCREW

RETAINING

RING

/

/

WEAR

PLATE

/

1

CAM

IMPELLER

826&

/

d. a e.

I

8260-8

FIGURE 26. PUMP

131-0165

38


,

.

Disassembly

(Pump 131-0257)

1. Disconnect all hoses and remove the pump from the engine.

2. Loosen the pulley set screw and remove the pulley from the pump shaft.

3. Remove the impeller housing screws, impeller housing, and gasket.

4.

Pull the impeller out of the impeller housing.

5.

Remove the wear plate from the pump housing, using a screwdriver to pry loose the plate if necessary.

6.

Remove the external retaining ring from the impeller end of the water pump shaft.

7. Remove the two piece seal assembly. The spring portion of the seal is removed first. The second portion of the seal can be loosened and removed with a screwdriver or needle-nose pliers.

8. Remove the internal retaining ring from the drive pulley end of the pump housing.

9.

Carefully drive out the shaft and bearing assembly from the impeller end of the housing.

10.

Remove the slinger from the water pump shaft.

Assembly (Pump 131-0257)

Inspect the impeller housing for wear, rough surfaces, or pitting and replace if any of these conditions exist. Replace any other worn components such as bearings, seals, or impeller and use a new impeller housing gasket.

1.

Install the new slinger on the water pump shaft.

2. Install the ceramic part

of

the two piece seal assembly

in

the pump housing. The rubber side of the seal should be toward the bearings.

3. Coat the inside of the water pump housing and the outside of the ball bearing races with grease.

4.

Insert the water pump shaft into the pump housing, and install the internal retaining ring in the drive pulley end of the housing.

5.

Install the spring portion of the two piece seal on the pump shaft and secure in place with the external retaining ring.

6.

Install the wear plate

so

that the notch in the plate fits into the machining in the pump housing.

7. Coat the inside of the impeller housing with grease.

8.

Install the impeller in the impeller housing by twisting it clockwise while pushing it into place.

9. While holding the gasket in place against the pump housing, install the impeller housingsecur- ing it with four screws removed during disassembly.

10. Mount the pump on the engine and attach the hoses.

11.

Align the pump drive pulley with the crankshaft drive pulley and tighten the set screw.

WEAR PLATE

IMPELLER

IMPELLER

HOUSING GASKET

I

\

SEAL ASSEMBLY

BEARINGS AND SHAFT

PUMP HOUSING

RING

FIGURE 27. PUMP 131-0257

39


AND

BEARING

FIGURE 28. CENTRIFUGAL PUMP 132-0110

Disassembly (Centrifugal Pump 132-01 10)

1.

Remove the water inlet fitting, drive belt pulley, cover screws, and pump cover gasket.

2.

Unscrew the threaded impeller from the pump shaft by turning the impeller in a counterclockwise direction when facing impeller.

3.

Slide the seal seat, wear face, and bellows as- semblyofftheshaft. Loosentheclampscrew and slide the pump body off the pedestal.

4.

Remove the bearing lock ring and drive the shaft and bearing assembly out of the pedestal. The bearing is press fit on the shaft and comes off in one integral part. The bearing is packed with a lifelong lubricant and is sealed at each end.

E

FRESH WATER

MAN I

FOLD

FLAT WASHER

(WHEN

USED)

Assembly (Pump 132-0110)

Replace all worn components such as bearings, seals, wear face, and impeller and use a new cover gasket. Assembly sequence is the reverse of the disassembly procedure.

HEAT EXCHANGER

Closed-type cooling systems are commonly referred to as fresh water cooling or heat exchanger cooling.

Water circulated throuah the enaine is called fresh water, hot water, etc. fiater circilated through the heat exchanger only is called raw water, sea water, cold water, discharged water, etc. This system with an anti-freeze coolant is recommended where freezing coditions exist, or where the owner wants to prevent the possibility of salt water or rust problems.

The closed water system continually recirculates captive water through the waterjacket, exhaust manifold, centrifugal pump, and one side of the heat exchanger. Figure29 shows a typical heat exchanger.

Do

nof use the exisfing neoprene impeller waferpump in fhe hof wafer side of the cooling system. Heat or soluble oil (in many rust inhibitors and anti-freezes) will damage the impeller. Instead, connect the neoprene impeller pump on the cold wafer side. Use a metal impeller, cenfrifugal-type wafer pump (Onan

732-07 70

or

equal) in ihe fresh wafer side. See Figure 28.

T O

HEAT

EXCHANGER

PUMP

SALT WATER

FIGURE 29. HEAT EXCHANGER

Maintenance: Maintain the closed water system the

Same as an automotive radiator cooling system.

Clean and flush Once a year and use anti-freeze if there

is

danger

of freezing.

Use

a rust

inhibitor in the closed

water system.

40

Cleaning: To clean the closed system, drain and fill with radiator Cleaner. When chemical Cleaning iS done, always flush the cooling system to wash out deposits loosened by the chemical cleaning.

Flush the engine water jacket

as

previously

dis-

cussed. First remove

the

water outlet hose from the engine water jacket to the heat exchanger. Flush both the open and closed water system sides of the heat exchanger. Remove the rubber impeller pump cover to flush theopen system. Also flush thewater-cooled exhaust manifold. When flushing

is

completed, check the system thoroughly for leaks.


.

Starting System

’

STARTER

’

.

A

solenoid-shift starter is shown in Figure 30. After

the starter button is pushed, battery current ener- gizes the start solenoid. The solenoid causes an arm to push the starter pinion into the flywheel ring gear.

Simultaneously, the start solenoid contacts close and allow the starter motor to start turning. The starter remainsengaged until thestart button is released. An overrunning clutch protects the starter from damage before it can be disengaged from the flywheel.

Beginning with Spec engines

is

the gear drive starter shown in Figure 30a.

S T A R T I N G M O T O R

*

b

FIGURE 30a. GEAR-DRIVE STARTER

START

BUTTON

CLUTCH

SHIFT ARM

SOLENOID

FIGURE 30.

Maintenance

For proper cranking-motor operation with a minimum of trouble, a periodic maintenance procedure should be followed. Periodic lubrication, inspection of the brushes, and commutator as described in this section will insure long cranking motor life. Periodic disassembly (see

Disassembly)

of

the cranking motor for a thorough overhaul is recommended as a safe- guard against accumulations of dust, grease, and parts wear.

Lubricate all oil-type bearings with 8 to 10 drops of light engine oil (SAE 20). All oil-less type bearings and bushings should be given afewdrops of light oil.

Lubricate the cranking motor drives with afew drops of light engine oil.

-

Never oil the commutator. Oil cranking ability

of

the motor. on the commutator reduces the

The gear drive is mounted on a shaft which extends from the starter motor. When not running, the drive pinion gear is retracted soit clears the flywheel ring gear. When starting, a spiral spring through increasing speed forces the drive pinion to engage the flywheel ring gear. The pinion and flywheel ring gear teeth have beveled ends that ensure their engaging properly.

The commutator can be cleaned by using number 00 sandpaper. Never use emery cloth. If the commutator is out of round or has high mica, remove it from the cranking motor. Turn the commutator down on a lathe being careful to remove onlyenough material to true up the commutator and remove high mica.

It is not necessaryto undercut micaon startermotorcommutators.

Replace worn brushes. If brushes wear rapidly, check for excessive brush spring tension and roughness or high mica on the commutator.

Starter motors are not designed

for

continuous operation.

Do

not operate more than

30 secondsper

ON

cycle.

Do

not operate starter more fhan

70

seconds in a stall condition i f engine will not rotate. Serious damage could result

if

these time limits are exceeded.

41

Solenoid Shift

Periodically inspect solenoid and shift lever to make sure they are operating properly. Keep the solenoid shift lever free of dirt and excess grease.


The overrunning clutch is packed in a special high melting point grease and after its initial assembly, needs no further lubrication. This clutch prevents the engine from turning the starter motor at too high a speed once it is started.

Do

not subject the overrun-, ning clutch to grease dissolving or high temperature cleaning methods. This may cause the clutch to lose some or all of its grease.

If the pinion does not turn freely in the clutch in the overrunning direction, or the clutch tends to slip in the opposite direction, replace the assembly. A worn clutch indicated by excessive looseness of the pinion req u i res replacement.

Never attempt to repair or relubricate a defective clutch.

Pinion Clearance

The pinion clearance is adjusted by increasing or decreasing the fiber washer thickness at the mounting surface of the shift solenoid.

More washers decrease the clearance while less washers increase the pinion clearance.

The clearance between the pinion and the housing should be 0.02 to 0.08 inch (0.5 to

2

mm) when the pinion is in the cranking position, Figure 30b.

Drive Pinion

The teeth of the drive pinion are chamfered on only one side and specially rounded and polished to make the automatic meshing with the flywheel ring gear more efficient. The drive

is

designed

so

that if the ends of the pinion teeth meetend toend with the ring gear teeth (keep in mind that the drive is freely mounted on the drive shaft), the drive assembly can move back aslight amount againstthe pressureof the driving spring. The longitudinal movement permits the pinion to turn farther and enter the flywheel ring gear.

It is important the correct length of drive spring be used when making replacements. The length of the drive spring controls the longitudinal movement

of

the bendix pinion (meshing and unmeshing of the pinion and flywheel ring gear).

’

Keep the drive shaft free of rust, burrs or bendsso the drive can move freely along it. A damaged pinion necessitates the replacement of the assembly.

Onan recommends replacement of faulty gear drive assemblies and provides no further service information concerning their repair.

For further repair information, contact the manufacturer of your starter motor.

4

Disassembly

1 . Remove all wires to the starting unit. Tag each wire so it can be reconnected as originally.

2.

Remove the solenoid (where applicable).

3. Remove the starter motor thru-bolts and divide the starter into three main assemblies- the front bracket, the housing, and the rear bracket. On some model starters, short screws are used to hold the three starter sections together (Figure

31).The spacers on the solenoid starters are used for adjustment of the thrust gap of the armature shaft and are located between the rear bracket and the commutator shaft.

On the solenoid shift models, the steel spacing washer is on the commutator side.

flm

PINION

MOTOR

GEAR

SHOULD BE BEMlEEN

0.02

to

0.08

INCH

(0.7”

FEELER GAUGE

-

.12”

CLEARANCE

SEETEXT)

FIGURE 30b. PINION CLEARANCES (GEAR DRIVE)

42


.

THROUGH BOLTS

ASSEMBLY

FIGURE 31. SOLENOID SHIFT

STARTER

4.

Solenoid

Starter

Only:

The armature can now be removed from the front bracket. Be careful not to miss thesmall steel washer used in the end

of

the armatureshaft. Removetheshift leveratthesame time the armature is removed. The spring holder, lever springs, and retainer can be removed prior to removing the lever (Figure 31a).

5.

Solenoid Starter Only: Remove the ring afterdriv- ing the pinion stopper toward the pinion gear,

using a cylindrical tool (Figure 32). Remove the

overrunning clutch and the pinion stopper

at the

same time.

6.

Gear Drive Starter

Only:

The entire assembly is mounted on the armature shaft. When disassem- bling the starter, pay particular attention to the various parts and their positioning in the starter

assembly (Figure 33). If the gears of the pinion

are damaged, replace the entire pinion. Inspect the screw shaft for rust and burrs.

7. Remove the brushes from the brushholder and inspect them (inspection of brushes and brush springs discussed later).

8.

Remove the pole shoes, if necessary, by rernov- ing the flathead machine screws which anchor them to the frame.

SOLENOID-SWITCH

ASS E MB LY

MRU-BOLTS i

FRONT BRACKET

ASSEMBLY

SHIFT

LEVER SPRING

I

HOLDER r I

"z

1

BRLISH

ARMATURE

OVERRUNNING

CLUTCH

SPACERS

FIGURE

31a. SOLENOID SHIFT

STARTER.

FIELD

COILS

ASSEMBLY

FIGURE 32. TOOL FOR DRIVING PINION STOPPER

43

PINION HOUSING

1

COVER BAND

FIGURE 33. GEAR DRIVE STARTER


ELECTRIC STARTER INSPECTION AND

TROUBLESHOOTING

Testing the Armature for Shorts: Place the armature in the growler and hold a thin steel blade parallel to the core and just above it, while slowly rotating the

armature in the growler (Figure 34). A shorted arma-

ture causes the blade to vibrate and move toward the core. A shorted armature must be replaced.

Testing the Armature for Open Circuit: The most common place for an open circuit is at the commutator riser bars. inspect conductors for loose connections at points where they are joined to the commutator bars.

Testing Commutator Runout: Place the commutator on a test bench and check runoutwith adial indicator

(Figure 36). When commutator runout exceeds 0.004 inch, reface the commutator.

, d

FIGURE

34. TEST FOR SHORTED ARMATURE

Testing Armature for Grounds: Touch armatureshaft or core and the end of each commutator bar with

a

pair of

ohmmeter leads (Figure 35). If the ohmmeter

reading is low, it indicates a grounded armature.

Replace a grounded armature.

FIGURE

36. CHECKING COMMUTATOR RUNOUT

Testing Armature Shaft Runout: The armature shaft as well as the commutator may be checked.

A

bent armature can often be straightened, but if the shaft is

worn a new armature is required (Figure

37).

FIGURE 35. TEST FOR GROUNDED ARMATURE

FIGURE 37. CHECKING ARMATURE SHAFT RUNOUT

44

Testing Field Coils for Grounds: After unsoldering the shunt field coil wire, place one test prod on the connector and the other on a clean spot on the frame.

If the ohmmeter indicates continuity, the fields are grounded either at the connector or

in

the windings

(Figure 37a).


4

ONE PROD

ON

FIELD COIL

LEAD. ONE PROD ON FRAME.

FIGURE 37a. FIELD COIL GROUND TEST

Testing Field Coilsfor Open Circuits:

Place one prod on the connector and the other on a clean spot on the

brushholder (Figure 38). If continuity is good, the

field coil is good. Check all brushholders in the same manner.

.28"

RCCK MCCK

FIGURE 39. BRUSH WEAR LIMITS

Inspection for

Brush Spring Tension:

Measure brush spring tension with a tension meter (Figure 39a).

Push the brush into its holder and take the reading just as the brush slightly projects from the brushholder. On a new brush thespring tension should be

49 to 59 ounces (1.37-1.65 kPa) for RCCK engines and 29 to 38 ounces (0.81 to 1.06 kPa) for MCCK engines.

FIGURE 39a. MEASURING BRUSH SPRING TENSION

Assembly:

Reassembly is much the reverse of disassembly procedure. Follow these precautions and procedures:

1. Cleanall partscarefullywithadryclothandcom- pressed air if available.

Do

not

immerse bearing equipped parts in cleaning fluid.

Clean wifh a brush dipped in mineral spirits.

Donof clean overrunning clufch in solvenf or liquid cleaning solufion. Washing the clufch will cause the grease

to

leak out.

ONE PROD

O N

FIELD COIL LEAD

ONE PROD ON BRUSH HOLDER.

SHOULD LIGHT.

FIGURE

38. TEST FOR OPEN FIELD COIL inspection of

Brushes:

When brushes are worn more than 0.3 inch, replace them. Figure39shows the wear

limit.

See that the brushes move smoothly

in

the brushholders.

45

2.

Apply20 weightoil to armatureshaftandsplines.

Use grease sparingly on solenoid starter shift lever pin, joint

of

shift lever and plunger, plunger and spacing washers at end

of

the shaft.

3. Use spacing washers to adjust armature end play of

0.004 to 0.020 inch (0.102 to 0.508 mm).

4. When assembling starter to engine oil base, do not draw the mounting bolts up tight. The gears should have 0.004 to0.007 inch backlash. Tap the starter in or out from the oil base to adjust. Then tighten starter mounting bolts to

Nm).

30

ft.-lb.

(41


Engine

Disasse.mbly

If engine disassembly is necessary, first remove all the. complete assemblies (e.g. manifold with carburetor and vacuum speed booster). Individual assemblies, as the carburetor, can be removed and serviced later, if necessary. Follow the general disassembly steps given below and refer to the appropriate detailed instructions in this section. When reassembling; check the text for special assembly instructions.

Keep

alt

parts

in

their respective order

.

.

. valve assemblies,. rod caps for respective rod and piston assemblies, etc. Analyze reasons for parts failures.

Use new gaskets for assembly.

6.

Install crank gear aligning timing mark with mark on camshaft gear.

7. Install valve assemblies and cylinder heads.

8. Install gear cover and

oil

seal.

9. Install flywheel.

10.

Install fuel pump, manifold assembly, air cleaner,

..

fuel lines, spark plug, breaker box, etc.

11. Connect electrical wires, exhaust line and battery.

12. Fill crankcase with proper oil.

.

GENERAL

~~

DISASSEMBLY

1. Drain crankcase oil.

2. Disconnect exhaust pipe7fuelline, and electrical connections.

3. Remove flywheel using Onan flywheel puller.

4.

Remove gear cover using care to protect oil seals from keyway damage.

5.

Remove snap ring and remove crankshaft gear using a gear pulling ring and gear pulter.

6.

Remove air cleaner, manifold assembly (with carburetor and vacuum speed booster), fuel pump, fuel lines, spark plugs, ignition breaker box, etc.

7.

Remove cylinder heads, oil base and oil pump.

8.

Remove valves, springs, tappets, etc.

9.

Remove camshaft and gear assembly.

t

0. Remove connecting rods, pistons and bearings.

11.

Remove rear bearing plate.

12.

Remove crankshaft.

Remove bearings as needed using correct bearing remover.

FLYWHEEL

To

remove the flywheel, turn the flywheel mounting screw outward about two turns and use Onan puller

420-0100 to pull the flywheel, Figure 40.

Do

not drop the flywheel. Always use astee1 key for mounting the flywheel.

FIGURE

40. ONAN

FLYWHEEL

PULLER

GENERAL ASSEMBLY

Engine assembly usually is the reverse of the disassembly procedure. Use a torque wrench whenever possible and observe proper clearances throughout assembly. Coat all internal parts with oil. During assembly, turn engine over by hand

- over freely.

1.

Install new main bearings, if required, using proper bearing driver.

2.

Install crankcase and rear bearing plate (check end play).

3.

Install pistons, rods, bearings and rod caps.

4.

Install crankshaft and timing gear assembly.

5.

Install oil pump and oil base.

GEAR

COVER

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

46

E3

installing the gear cover, make

sure that roll

pin in fhe

gear

cover

engages fhe governor

cup

correctly. Figure

41.

Turn the governor cup

so

that the plastic bushed hole is at the three o’clock position. Thesmooth 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 thegear cover is installed flush against the crankcase. becareful not to damage the gear cover oil seal. Adjust the roll

(stop) pin to protrude to ajoint 3/4 inch from the cover

mounting surface. See Figure

41.


b

.(

1

4

~VRNOR

CUP

OVERNOR

ARM

ROLL P

ROTATE

GOVERNOR CUP

SO THAT ROLL PIN'

FITS INTOTHE

HOLE IN PLASTIC

BUSHED CUP.

GOVERNOR

SHAFT

YOKE

I

IF FEELEW WILL

ENTER H O E

1

(13 mn).

FALLEN OUT

FIGURE 41. GEAR COVER ASSEMBLY

GOVERNOR CUP

With thegearcover removed, thegovernorcup can be taken off after removing the snap ring from the camshaft center pin. Catch the flyballs while sliding

the cup off. See Figure

41.

Replace any flyball that is grooved or has aflat spot. If the arms of the ball spacer are worn or otherwise damaged. replace the entire timing gear set. The governor cup must spin freely on thecamshaft center pin without excessive loosenessor wobble. If the race surface

of

the cup is grooved or rough, replace it with a new one.

When installing the governor cup, tilt the engine

so

the gear is up, put the flyballs in placeand install the

WHEN GOVERNOR

IS

PROPERLY

ASSEMBLED THE

DIMENSION SHOWN

ON DRAWING

WILL

BE AS INDICATED.

CENTER

PIN

GOVERNOR

CUP

GOVERNOR

FLYBALL

88

FIGURE 42. GOVERNOR CUP

cup and snap ring on the center

pin, Figure 42.

The camshaft centerpin extendsout 3/4inchfromthe end of the camshaft. This distance provides and

in

and out travel distance of cup, as illustrated. Hold the cup against the flyballs when measuring. If the distance is less (the engine may race, especially at no load), remove the center pin and press a new pin in only the required amount. otherwise, grind

off

the hub of the cup as required.

The camshaft center pin cannot be pulled outward nor removed without damage. If the center pin extends out too far, the cup will not hold the flyballs properly.

.

TIMING GEARS

If replacement of either the crankshaft gear or the camshaft gear becomes necessary, install both gears new, never one only. Use agear pulling ring to remove the crankshaft gear. Be sure to remove the snap ring first.

The camshaft gear is pressed on and keyed to the

Camshaft. The camshaft and gear must be removed as an assembly after first removing the crankshaft gear lock ring and washer. Before removing the camshaft and gear assembly, remove the cylinder head and valve assemblies. Remove the operating plunger for the breaker points. Remove the fuel pump and tappets.

The camshaft may be pressed out of the gear by use of a hollow tool or pipe which will fit over the camshaft center pin. Do not press on thecenter pin or damage it in any way. The governor ball spacer is a press fit to the camshaft gear.

When pressing a camshaft gear onto the camshaft, be sure the gear is started straight and that the key is properly in place. Install the governor cup assembly before installing the camshaft and gear in the engine.

47


FIGURE 43. TIMING GEAR REMOVAL AND

INSTALLATION

Each timing gear is stamped with an

"0"

the edge. The gear teeth must

mesh so

that these marks coincide exactly when thegears are installed in

the engine, Figure 43.

Be

sure, when installing the camshaft gear and shaft assembly, that the thrust washer

is

properly in place behind thecamshaft gear.

Replace the camshaft retaining washer and lock ring to the crankshaft.

CYLINDER HEADS

The cylinder head should be tightened in the order designated per Figure 44to a torqueof 5foot-pounds

(6.8 Nom), then

10

foot-pounds (13.5N.m). etc. until

all

are torqued to 29 to 31 foot-pounds

(39-42

VALVES

Properly seated valves are essential to good engine performance. The cylinder head is removable for vaiveservicing.

Do

not use apry to

loosen

the cylinder head. Rap sharply on the edge with a soft-faced hammer, taking care not to break any cooling fins. A conventional type valve spring litter may be used when removing the valve spring locks, which are of the split type. Clean all carbon deposits from the cylinder head, piston top, valves, guides, etc. face is burned

If

avalve or warped, or the stem

worn,

install a new valve.

FIGURE 44. CYLINDER

HEAD BOLT TORQUE SEQUENCE

Worn valve stem guides may be replaced from inside

the valve chamber. See Figure 45.

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 are atso replaceable from thevalve chamber, after first removing the valve assemblies.

NOTE SEE VALVE

T A P P E T

CLEARANCES

IN

TEXT

VALVE

RETAINE

I

FIGURE 45. VALVE SYSTEM

48.


TAPPET ADJUSTMENT

The engine

is

equipped with adjustable tappets. To make a valve adjustment, remove the valve covers.

Crank the engine

over slowly by hand until the

left hand intake valve. when facing the flywheel, opens and closes. Continue about

1/4

turn until the correct timing marks align. This should place the left hand piston at the top of its compression stroke, the position it must be in to get proper valve adjustment for the left hand cylinder. Clearances are shown

in

DIMENSIONS AND CLEARANCES

section. For each valve. the gauge should just pass between the valve

stem and valve tappets (Figure

47).

INTAKE AND EXHAUST VALVES

(SEE TABLE

O F

CLEARANCE

FIGURE

46.

VALVE FACE AND

The valve face angle

IS

degrees. The valve seat angle is 45 degrees. This 1 degree interference angle results in a sharp seating surface between the valve and the top

of

the valve seat. The interference angle method of grinding valves minimizes face deposits

and lengthens valve life, Figure

46.

The valves should not be hand lapped, if at all avoidable, since the sharp contact may be destroyed.

This is especially important where chromecobalt faced valves and seats are used. Vaive faces should be finished in a machine to 44 degrees. Valve seats should be ground with a 45 degree stone and the width of theseat bandshould be 1/32to3/64(0.79-1.2 proper seating.

Remove all grinding compound from engine parts and place each valve in its proper location. Check

' each valve for a tight seat, using an air pressure type

: testing tool. If such a tool is not available, make pencil marks at intervals across the valve face and observe if the marks rub off uniformly when the valve

is

rotated part of a turn against the seat.

Lightly oil the valve stems and reassemble all parts removed. Adjust the valve clearance (see Tappet

Adjustment j.

The positive type valve rotocoils serve to prolong valve life and decrease valve repairs. Check the rotocoils periodically by removing the cylinder heads and cranking the engine. When functioning properly, the

valve

is rotated

a

fraction of

a

turn each time it iopens. If rotocoils are faulty, install new ones.

FIGURE 47.

To correct the valve clearance, turn the adjusting screw as needed to obtain the right clearance. The screw is self-locking.

To adjust the valves on the right hand cylinder. crank the engine over one complete revolution and again line up the correct timing marks. Then follow the adjustment given for the valves of the left hand cylinder.

PISTON

AND RINGS

Whenever there is a noticeable wear ridge at the top of each cylinder, remove the ridge with a ridge reamer before removing the pistons. If not. the rings can catch the ridge when pushing out the pistons and

cause a ring land fracture, Figure 48.

To remove the piston and connecting rod assemblies, turn the crankshaft until a piston is at the bottom of the stroke. Remove the nuts from the connecting rod, bolts. ILift the rod bearing cap from the rod and push the rod and piston assembly out the top of the

49


CY Ll

N D E R

REMOVING P I S T O N WITH LARGE WEAR

RIDGE COULD BREAK RING O R RING LAND.

FIGURE 48. WEAR RIDGE

ON

CYLINDER WALL

cylinder with t h e handle end

of a

hammer. Be careful not t o scratch the crankpin o r the cylinder wall when removing these parts.

Keep the connecting rod bearing caps and bearings with their respective

rods.

The pistons

are

fitted with two compression rings and o n e oil control ring with a n expander. Remove these rings from the piston using

a

piston ring spreader.

Clean the piston ring grooves with agroove cleaner o r t h e end

49.

All

of a

broken ring filed

t o a s h a r p point, Figure

passages should be cleaned with

a

non-caustic solvent. Clean the rod bores and t h e back of the connecting rod bearings thoroughly.

Mark each piston to make sure t h e rod will be assembled on t h e piston from which it was removed.

Remove t h e piston pin retainer from each side and push t h e pin out.

Inspect th e pistons

for

fractures at t h e ring lands, skirts and pin bosses. Check for wear a t t h e ring land using new rings and

a feeler

g a u g e

as

shown in Figure

50.

for

See

DlAdENSlONS AND CLEARANCES

section proper side clearance measurement and ring groove widths.

1

.

#

4

FIGURE 49. CLEANING PISTON RING

GROOVES

50

FIGURE

50.

INSPECTING

RING

LANDS


CYLINDER

W A L L

FIGURE 51. NEW RING

IN

WORN PISTON RING GROOVE

Improper width rings or excessive ring side clearance can result in ring breakage. New rings

in

worn ring grooves do not have good cylinder wall contact,

Figure

51.

Replace pistons showing signs

of

bad scoring or burring, excessive skirt clearance, wavy or worn ring lands, fractures or damage from detonation. Replace piston pins showing fractures, scored bores or bores out

of

round more than 0.002 inch (0.051 mm).

Use a new piston pin to check the pin bushing in the connecting rod for wear. The clearance should

be

as shown in DIMENSIONS AND CLEARANCESsection.

Before installing new rings on the piston, check the ring gap by placing each ring squarely in its cylinder at

a

position corresponding to the bottom of its travel

(Figure 52). The gap between the ends of the ring is

given in DlMENSlONS AND CLEARANCES section.

.

PISTON .RING IN

CY LlNDER BORE

F E E L E R G A G E

FIGURE

52.

FITTING

PISTON RINGS TO

CYLINDER

Rings which are slightly oversize may be filed as necessary to obtain the correct gap, but do not use rings which require too much filing. Standard size rings may be used on

0.005

inch oversize pistons.

Other oversize rings must be used with corresponding oversize pistons. Rings of the tapered type are usually marked top

on

one side, or identified in some other manner and the ring must be installed with this mark toward the closed end of the piston.

Space each gap one third of the way around the piston from the preceding one, with no gap directly in line with the piston pin. The bottom piston ring groove should

be

fitted with an expander and an

oil

control ring and the two upper grooves fitted with compression rings. If a chrome faced ring is used, it will be in the top groove. Theoil control ring is selected for best performance in regard to the correct unit pressure characteristics.

The piston is fitted with a full-floating type piston pin.

The pin is kept in place by two lock rings

in

the piston, one at each side. Be sure these lock rings are properly in place before installing the piston and connecting rod in the engine. Refer to

DIMENSIONS A N D

CLEARANCES section for the correct piston-to- cylinder clearance.

CONNECTING RODS

The connecting rods should be serviced at the same time the pistons orrods are serviced. Rods must be removed with the piston. Replaceable bushings and

. bearings are used.

Proper clearance is obtained by replacing the pin bushing and the bearings. The rod bearings are precision size and require no reaming.

Install the connecting rods and caps with raised lines

(witness marks) aligned and with the caps facing toward the oil base. The rod and cap numbered

2

fits on the crankshaft journal nearest the bearing plate.

Coat the crankshaft journal bearing surfaces with oil before installing the rods. Crank the engine by hand to see that the rods are free. If necessary, rap the connecting rod cap screws sharply with a soft-faced hammer to set the rod square on the journal.

Checking Bearing Clearance

With

Plastigage: Make certain that all parts are marked or identified so that they are reinstalled in their original positions.

Place a piece of correct size Plastigage in the bearing cap the full width of the bearing insert about 1/4 inch

(6.35

mm) off center, Figure 53.

Rotate the crank about 30 degrees from bottom dead center and reinstall the bearing cap.Tighten the bolts to the torque specified in the ASSEMBLY TORQUES section.

Do

not turn the crankshaft.

Remove the bearing cap. Leave the flattened

51


6.

Reading A compared to C and reading B compared to

D indicates whether or not the cylinder is out of round.

If cylinder is out of round 0.002 inch (0.051 mm), rebore and hone cylinders for next oversize piston.

FIGURE

53.

MEASURING BEARING CLEARANCE WITH

PLASTIGAGE

Plastigage on the part to which it has adhered and compare the widest point with thegraduations on the

Plastigage envelope to determine bearing clearance.

CYLINDER

BLOCK

inspection:

1.

Make

a

thorough check for cracks. Minute cracks may be detected by coating suspected area with a mixture of 25 Wipe the part dry and apply a coating

of

zinc oxide (white lead) dissolv- ed in wood alcohol. If cracks are present, the white coating will become discolored at defective area.

2.

Inspect cylinder bore for scoring. Check Welsh plugsfora tight, even fit and the finsfor breakage.

3.

Check cylinder bore for taper, out of round and wear with a cylinder bore gauge, telescopegauge

or inside micrometer, Figure

54.

These measurements should be taken at four places

- near top and bottom of piston ring travel.

4.

Referring to Figure54, measure cylinderdiameter and record the readings as follows: a. Measure reading A across top of cylinder where greatest piston ring wear occurs. b. Measure reading

B

across cylinder at bottom of piston ring travel. c. Measure reading C across

top of

where greatest ring wear occurs. cylinder d. Measure reading

D

across cylinder at bottom

of

piston ring travel.

5.

Compare reading A with reading

B,

reading C with reading

D

to determine cylinder taper due to wear.

If

taper exceeds

0.005

inch

(0.127

mm), rebore and hone cylinder to accommodate the next oversize piston.

52

lL7Z,.

TOP

END

OF

CYLINDER

.\

8418

BOTTOM

OF

RING TRAVEL

k

FIGURE 54. CYLINDER BORE MEASUREMENT


L

Y

8.

Clean cylinder block thoroughly with soap, water and clean

rags.

A

clean white rag should not be soiled on the

wall

after cleaning

is

complete.

cial cleaners to clean cylinder bores after degiazing or honing. These solvents will

not

remove abrasives

from

the walls. Abra- sives

not

removed from engine will rapidly wear rings, cylinder walls, and bearing surfaces of all lubricated parts.

Never use gasoline

or

commer-

9.

Dry crankcase and coat it with oil.

I

.I

FIGURE 55. HONING CYLINDER

HONING PROCEDURE

1.

A

hone can be used to rebore a cylinder, Figure

55.

Remove stock to 0.002 inch (0.051 mm) less than finished bore with coarse hone (100 grit), then complete honing with finish hones (300grit).

2.

Anchor block solidly foreither vertical or horizon-

tal

honing. Use either a drill press or heavy-duty drill which operates at about 250. to 450 rpm.

3.

Lower hone into cylinder until it protrudes 1/2 to

3/4 inch

(1 to

19 mrn) past end of cylinder. Rotate adjusting nut until stones come in contact with cylinder wall at narrowest point.

4.

Loosen adjusting nut until hone can be turned by hand.

5,

Connect drill to honeand start drill. Move hone up and down in the cylinder about 40 cycles per minute. Usually the bottom of the cylinder must be worked out first because it

is

smaller. When cylinder takes a uniform diameter, move hone up and down all the way through the bore. Follow the hone manufacturer’s recommendations for wet or dry honing and oiling the hone.

6.

Check diameter of cylinder regularly during honing. A dial bore gauge is the easiest method but a telescoping gauge can be used. Check the size at

six

places in the bore: measure twice at the top,

I

- middle and bottom at 90 degree angles.

.

When the cylinder is about 0.002 inch (0.051 mm) within the desired bore, change to finestones and finish the bore. The finish should not be smooth

but as shown in Figure 56. The crosshatch formed

by the scratching of the stones should form an angle of 23 degrees. This can be achieved by moving the hone

up

and down in the cylinder about 40 cycles per minute.

53

AVOID

THIS

FINISH

PRODUCE CROSS HATCH SCRATCHES

FOR FAST RING SEATING


PRECISION TYPE

Do not

line ream

or

bore.

------

----

-----.----

ALIGN HOLE IN BEARING

WITH HOLE IN BEARING BORE

1

LOCK PIN

CAMSHAFT BEARING

.

OIL

HOLES I N BEARING BORE

BEARING

CRANKSHAFT BEARING

FIGURE 57. INSTALLATION OF CAM AND CRANKSHAFT

BEARINGS

BEARINGS

Removal of the camshaft or crankshaft bearings requires complete disassembly of the engine. Use a press or a suitable plug to remove the bearings.

Support the casting to avoid distortion and avoid damaging the bearing bore during removal and installation. Use oil on the bearings to reduce friction when installing and again lubricate with oil after

installing. See Figure 57. Use combination bearing

driver to install the camshaft bearings.

Camshaft

Replacement camshaft bearings are precision type which do not require line reaming or line boring after- installation. Coat the bearing with lubricating oil to reduce friction. Place the bearing on the crankcase over the bearing bore with the lubricating hole (front only) in proper position. Be sure to start the bearing straight. Press the front bearing in flush with the outside end of the bearing bore. Press the rear bearing in until past the ignition plunger hole.

Crankshaft

New crankshaft, main bearings are precision type which do not require line reaming or line boring after installation. Before putting in the main bearings, expand the bearing bore by placing the casting in hot water or in an oven heated to 2OOOF practical, cool the precision bearing to shrink it.

For putting in either the front or rear main bearing, using instructions following, always align the oil hole(s) in the bearing bore. Theoil passage must beat least half open. The cold oiled precision bearing should require only light taps to position it. Install the bearing flush with the inside end of the bore.

If

the head of a lock pin is damaged, use side cutters or

"Easy-Out'' tool to remove pin. Then install a new lock pin. Apply oil to the thrust washers to hold in place when

thecrankshaftisinstalled.Theoi1groovesin

thrust washer bearing must face the crankshaft. Be sure two notches fit over lock pins.

OIL SEALS

The bearing plate must be removed to replace its oil seal. Drive the oil seal out from the inside using a bearing plate driver and gear cover driver. See Special

Tools

section.

Before installing the seals, fill the space between sealswith afibrousgreaseorstiff cup grease.Thiswil1

improve sealing. See Figure 58.

I

"

.

Use heavy fiber or cup .grease in between seal improve seal.

1

REAR BEARING PLATE

GEAR COVER

OIL

SEAL^

MOUNTING FACE

OF GEAR COVER

/4

I - 1/32''

(26.2

mrn)

THIS SURFACE SHOULD BE

CLEANED OF A L L OLD

SEALING COMPOUND BE-

FORE INSTALLING SEAL.

THIS SURFACE SHOULD BE

CLEANfD OF A L L OLD

SEALING COMPOUND BE-

FORE INSTALLING SEAL.

A877

GEAR COVER O!L SEAL

DRIVE OR PRESS OIL

SEAL TO SHOULDER

OFTHEPLATEBORE

REAR BEARING PLATE

O I L SEAL

FIGURE

58. GEAR COVER AND REAR BEARING PLATE OIL SEALS

54


t

L

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

1-1/32

(26.2 mm) of an inch from the mounting face

of

the 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

shim stock around the end of the crankshaft when replacing the bearing plate to avoid damaging the seal. Remove the shim stock as soon as the plate is in place.

CRANKSHAFT

ENDPLAY

After the rear bearing end plate has been tightened using the torque recommended in ASSEMBLY

TOR-

OIIES section, check the crankshaft endplay as

shown in Figure 59. If there

is

too much endplay (see

DIMENSIONS AND

CLEARANCES

section for minimum and maximum endplay). remove the rear bearing end plate and replace the gasket with a thinner gasket from the gasket kit. For too little endplay. remove the rear bearing end plate and replace the gasket with a thicker one. Reinstall the end plate making sure the thrust washer notches line

ap

with the lock pins. Torque and recheck endplay of the crankshaft.

(Refer to

Table of

Clearances)

FIGURE 59. MEASURING

CRANKSHAFT ENDPLAY

OIL PUMP

Check the oil pump thoroughly for worn parts. Oil the pump to. prime it before reinstalling. Except for gaskets, the component parts of the pump are

not

available individually. The suction cup is available separately. Install a new pump assembly, if required.

55


Wiring Diagram

LEGEND

El, E2

81

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

SPARK PLUGS

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

STARTER

BTl

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

BATTERY

S1'

S2'

S3

T I

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

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

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

START SWITCH

IGNITION SWITCH

BREAKER

POlNTS

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

IGNITION COIL

T81...

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

TERMINAL

BOARD

*

-

CUSTOMER SUPPLIED.

8 3 1 7

FROM STARTER

SOLENOID TERMINALS

BATTERY IGNITION SYSTEM

TI

El

56



Cummins Power Generation

1400 73rd Avenue N.E.

Minneapolis,

MN 55432

763-574-5000

Fax:

763-574-8087

Cummins and Onan are registered trademarks of Cummins

Inc.


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