6. CYLINDER HEAD/VALVES
TROUBLESHOOTING
• The poor cylinder head operation can be diagnosed by a compression test or by tracing engine
top-end noises.
Poor performance at idle speed White smoke from exhaust muffler
• Compression too low • Worn or broken valve stem or valve guide
• Damaged valve stem seal
• Worn piston rings
Compression too low
• Incorrect valve clearance (too small)
• Burned or bend valves Abnormal noise
• Incorrect valve timing • Incorrect valve clearance (too small)
• Broken valve spring • Burned valve or rocker arm
• Poor valve and seat contact • Worn camshaft or cam follower
• Leaking cylinder head gasket • Worn valve guide
• Warped or cracked cylinder head
• Poorly installed spark plug
Compression too high
• Excessive carbon build-up in combustion
chamber or on piston head
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