Onan MJA Series Service Manual page 80

78 CYLINDER HEADS AND VALVES
TROUBLE-SHOOTING CHART 8. CYLINDER HEADS AND VALVES
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TROUB LE POSSIBLE CAUSE REMEDY
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Poor compression L.eaky h~ad gasket or spark
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Replace gasket.
plug gasket.
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Valves sticking.
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Broken valve spring.
Leaky valves.
Burned valves and seats. Regrind valves arid
seats.
Insufficient valve
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clearance.
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Adjust clearance.
Weak valve springs.
Replace' weak springs.
Excessively strong
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valve springs. . Replace springs.
Worn guides which set
, up thrust action.
Replace guides.
Excessive valve
Adjust valve
clearance.
clearance.
Close valve clearance.
Re-adjust valve
clearance.
Weak springs.
Replace springs.
High temperatures,
Check for engine
causing valve stretch.
overheating.
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Valve seat or face off
Regrind seat, replace
center.
valve.
Loose valve seat inserts.
Replace seats. Rebore
and use oversize if
necessary.
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Valve breakage
Valve burning
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See Sticking Valves,
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this chart. .
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Replace spring, check
(,
valve condition.
Regrind valves.
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