Onan MJA Series Service Manual page 18

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TROUBLE-SHOOTING CHART 1, THE ENGINE (Cont. )
Dull, metallic Loose crankshaft bear ­
tlmd, if not bad
ing.
may disappear
after few minutes
,of
operation
Sharp,
metallic
1
Low oil supply.
thud;
especially
when cold engine. Oil badly diluted.
first started.
Tapping sound, Valve clearance too
clacking; light great.
cliCking
Broken valve spring.
Metallic knock Worn connecting rod
under no load bearings.
•conditions and
when stopping
I
TROUBLE POSSIBLE CAUSE
Excess oil con- Oil leak from oil base or
sumption, no in- connections.
crease in smoke
I
Leaky crankshaft oil
seals.
Black, smoky ex-
must, excessive
fuel consumption,
fouling of spark
plugs
with
black
soot, possible
lack of power
under load
Fuel mixture too rich.
Choke not open.
i
Clogged air intake.
I
RE:MEDY
Inspect engine, check
for clogged crankcase
breather.
Inspect oil seals, Sect
3. 9.2.2 and Sect 3. 9. 5. 5
Check for clogged
crankcase breather.
Adjust carburetor
Sect 3.2.5.
See Sect 3.2.4.
Clean air cleaner,
Sect 3.2.6.
Replace bearing.
Add oil.
Replace oil.
Check valve clearance
Sect 3.7.1.
Replace valve spring.
Replace bearings.
Loose piston. ,
Check piston clearance.
,Bollow clIcking
•sound
with
engine
,cool and under
load.
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