Engine
Disassembly
DISASSEMBLY/ASSEMBLY
When complete engine disassembly is necessary,
first remove all ComDleteassemblies. Individual assem-
1.
Use the proper bearing driver to install front main
bearing after coating
it
with a light film of oil.
2.
Insert rear main bearing in rear bearing
plate.
blies
disassembled and repaired
at
another time.
as
“el
pump
and carburetor
can
be
3.
Insert crankshaft,rear bearing plate, and crank-
shaft gear.
Suggested Disassembly Order
1.
Drain crankcase.
2.
Disconnect all exhaust lines and electrical lines.
3.
Remove engine from its mountings and place
on
a suitable bench or work stand.
4.
Remove all housings, shrouds, blower housings,
etc.
5.
Remove flywheel, using a puller.
6.
Remove the gear cover, being careiul to protect
7.
Remove the crank gear, using a gear puller and
8.
Remove all accessories such as oil filter, starter,
9.
Remove breaker point box.
the oil seal from keyway damage.
ring.
intake manifold, fuel lines, spark plugs, etc.
10. Remove oil base,
oil
pump and cylinder heads.
11. Remove valves, springs, lifters, etc.
12. Remove camshaft and gear assembly.
13.
Remove connecting rods and pistons.
14.
Remove rear bearing plate, crankshaft, and front
bearing.
4.
Install piston and connecting rods.
5.
Install camshaft and gear assembly; align crank
gear mark with cam gear mark.
6.
Install valve assemblies, oil pump, oil base, and
cylinder heads.
7.
Install breaker point box.
8.
Install all accessories such as oil filter, starter,
9.
Install gear cover with oil seal and flywheel.
fuel lines and spark plugs.
10.
Set breaker points to obtain proper timing.
11.
Check valve clearance.
12. Install all housings and air cleaner.
13.
Fill crankcase with oil.
Operation
Start engine and check oil pressure. Run for approxi-
mately
15
minutes to bring engine to operating
temperature. Check for oil leaks, fuel leaks and exhaust
leaks. Adjust carburetor and governor for speed and
sensitivity.
Testing Compression
The compression tester is used
to
determine the
condition of valves, pistons, piston rings and cylinders.
To check compression:
Keep all parts in their respective orders. Keep valve
assemblies together. Return rod caps to their respec-
tive
pistons. Analyze the reasons for parts failure.
1.
Run the engine until thoroughly warm.
2.
Stop engine and remove spark plugs.
Suggested Assembly Procedure
Engine assembly is normally the reverse of the
disassembly procedure, observing proper clearances
and torques. Use a torque wrench to assure proper
tightness. Coat the internal engine parts with oil as
they are assembled. After the internal engine parts
are assembled, the engine should turn over by hand
freely. Use only genuine Onan parts and special
tools
when reassembling your engine.
3.
Remove air cleaner and place throttle and choke in
4.
Insert the compression gauge in one spark plug
Refer to
SPEClFlCATlONS
SECTION
for compression
pressures. There may be variations due to temperature,
atmospheric conditions and altitude. These pressures
are for a warm engine at cranking speed (about
300
the wide open position.
hole.
-.
rpm).
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