ENGINE DIVISION SERVICE MANUAL
CHART NO. 21
SMOKE FROM VEHICLE EXHAUST SYSTEM
The color or type of visible smoke from vehicle exhaust can provide clues as to the source of the problem. Three types of
"smoke" are generally common to gasoline engines:
Visible white "smoke" in exhaust results from coolant entering the combustion chambers or exhaust system. Check for failed
cylinder head gasket or cracked cylinder head casting. If ok, check for cracked crankcase.
Results from over rich fuel mixture. Check for partially closed choke, or carburetor flooding condition. An over rich mixture
usually causes rough engine operation. Perform steps covered in Diagnostic Chart No. 15.
Blue or Blue-gray Smoke
Results from oil entering the combustion chambers or exhaust system. Check PCV system per CTS* Emission Control
1. Blue smoke noted during wide open throttle operation indicates worn or stuck piston rings.
2. Blue smoke noted during deceleration (high vacuum) indicates failedor worn valve stem seals or worn valve guides.
Refer to appropriate CTS * engine section for repair of above difficulties.
* See CTS or CGES
CGES-215 - Page 39
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