Engine - Blue Smoke On Start-Up

Group Ref.: Engine Fuel & Emission

Bulletin No.: 376514

Date: December, 1993

SUBJECT:
BLUE SMOKE ON START-UP
(REPLACE VALVE STEM SEALS)

MODELS:
1985-93 CHEVROLET CAPRICE WITH 4.3L (LB4) ENGINE
1985-86 PONTIAC PARISIENNE, GRAND PRIX AND BONNEVILLE WITH 4.3L (LB4) ENGINE
1985-93 CHEVROLET AND GMC C/K, G, M/L, S/T, AND P TRUCKS WITH 4.3L ENGINE
1991-93 OLDSMOBILE BRAVADA WITH 4.3L ENGINE

CONDITION:

Some owners may comment that they observe blue smoke coming from the tailpipe of their vehicle immediately after they start their engine. The condition generally occurs after the vehicle has been parked for several hours.

CAUSE:

Oil leaking down the valve stem(s) into the cylinder(s) after the engine is shutdown. When the engine is restarted, the oil that has leaked into the cylinder is ignited, causing the blue smoke.

CORRECTION:

Replace all intake and exhaust valve stem seals. Use the V8 umbrella style exhaust valve stem seal. The umbrella style seal is recommended for service because it is easier to install than the O-ring style exhaust valve stem seal used in production. Barrel style seals continue to be used on the intake valve (same as production). Follow the procedure published in the appropriate service manual for valve stem seal replacement.

WARNING:
Improper seal installation may cause a condition worse than the original concern.





PARTS INFORMATION:

Parts are currently available from GMPSO.

WARRANTY INFORMATION:

For vehicles repaired under warranty, use:

Labor Operation: J0547

Labor Time: Use published labor operation time.