Subject: 5.7L LS1, 6.0L LS2, 5.3L LS4, 5.7L LS6, 7.0L LS7, 5.3L L33, 5.3L LH6, 5.3L LM4 - Engine Oil Leak at Rear Cover Assembly Area (Engine Block Porosity RTV Repair Procedure) #05-06-01-034B - (10/02/2006)

Models: 2004-2006 Buick Rainier

2003-2007 Chevrolet Corvette, TrailBlazer

2004-2006 Chevrolet SSR

2005-2006 Chevrolet Silverado, Silverado SS

with 5.7L, 6.0L, 5.3L or 7.0L Engine (RPOs LS1, LS6, LS2, LS4, L33, LH6, LM4, LS7)

Condition
Some customers may comment on an engine oil leak.

Cause
Upon initial diagnosis, it may be determined that the leak is coming from the rear cover gasket. This condition may be caused by engine block porosity on the sealing surface.

Correction
Follow the steps for Oil Leak Diagnosis in SI to determine the source of the leak. If the leak has been diagnosed as coming from the engine rear cover assembly, refer to Engine Rear Cover Replacement in SI and remove the engine rear cover assembly. Inspect for engine block porosity where the engine rear cover mates to the engine block. If porosity is found anywhere on the sealing surface, use the following procedure to apply RTV to repair the engine block porosity.

Important: Clean any residual oil from the block and cover before applying the sealant in the next step.

Wipe a small amount of RTV, P/N 12378521 (in Canada, use P/N 88901148), onto the surface using a plastic scraper to fill the porosity.
Remove any excess RTV material, especially from inside the high pressure oil passage. Refer to #1 in the above illustration.
Allow the RTV to cure for 10 minutes.
Important: Refer to Engine Rear Cover Replacement in SI and follow the tightening specifications and sequence.

Reinstall the engine rear cover using a new gasket and a new crankshaft rear main seal. Refer to Engine Rear Cover Replacement in SI.