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1992 - 1996 Corvette: Service Bulletin: Oil Leaks Between Intake Manifold and Engine Block

Source: Chevrolet Dealer Service Bulletin
Subject: Oil Leaks Between Intake Manifold and Engine Block
Model and Year: 1992-96 Chevrolet Corvette
Bulletin Number: 77-61-17
Date: 06-Oct-1997

CONDITION:

Oil leaks at mating surfaces between the intake manifold and engine block sometimes called "China Wall."

CAUSE:

Insufficient RTV bonding between the intake manifold and cylinder block.

CORRECTION:

It is very important to identify the source of the leak.Clean and dry area thoroughly before inspection.Use black light and oil dye to identify the source.If the China Wall area is found to be the source of the leak, reseal the mating surfaces with "3 Bond" RTV (P/N 12346141).

We believe this source and their product to be reliable.There may be additional manufacturers of such products.General Motors does not endorse, indicate any preference for or assume any responsibility for the products form this firm or for any such items which may be available from other sources.

It is extremely important that the mating surfaces be properly cleaned before applying the RTV.

Scrape off original sealer and any foreign material from the intake manifold and engine block.Avoid scratching surfaces and do not allow any debris to fall into the engine.Do not use any type of high speed rotary discs.

Wipe surfaces clean with a clean dry cloth and cleaners solvent.Pay particular attention to the four corners where the heads meet the front and rear China Wall area of the block.Again ensure that particles do not fall into the engine.Wipe surfaces clean with a clean dry cloth and cleaner solvent.

Prime the mating surfaces with the new RTV sealant by rubbing the surfaces with a small amount of wet RTV on a clean cloth.Then wipe off the excess RTV.

Firmly apply a ¼ inch (5mm) diameter bead of RTV into each of the four corners where the heads meet the block.Then, apply a ¼ inch (5mm) bead of RTV to the front and ear areas of the engine block, going up the cylinder heads approximately 3/8 to ½ inch (10 to 12.7mm).

While RTV is still wet, install the intake manifold and gaskets per service manual procedures.Take care not to push the RTV out of position.After assembling the engine, let RTV cure for at least 2 hours before driving vehicle.

© Copyright General Motors Corporation. All Rights Reserved

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