6. CYLINDER HEAD/VALVES DOWNTOWN 125i
SPECIAL TOOLS
Valve spring compressor A120E00040
TROUBLESHOOTING
· The poor cylinder head operation can be diagnosed by a compression test or by tracing engine
Poor performance at idle speed White smoke from exhaust muffler
· Compression too low · Worn valve stem or valve guide
· Damaged valve stem oil seal
Compression too low
· Incorrect valve clearance adjustment Abnormal noise
· Burned or bend valves · Incorrect valve clearance adjustment
· Incorrect valve timing · Sticking valve or broken valve spring
· Broken valve spring · Damaged or worn camshaft
· Poor valve and seat contact · Worn cam chain tensioner
· Leaking cylinder head gasket · Worn camshaft and rocker arm
· Warped or cracked cylinder head
· Poorly installed spark plug
Compression too high
· Excessive carbon build-up in combustion
chamber
6-3
4.7 / 5