Valve cover gasket

[Palut]

This may be a stupid question, but if a valve cover isn't warped at all, and is tightened to the proper specification, but the gasket still leaks, must the gasket be damaged? Or can oil seep through the gasket with no visible damage?

 

[moribundman]

I think it is important to be very anal about cleaning the mating surfaces before installing new VC gaskets. A small speck of dirt can cause a leak. I use acetone on the metal parts and brake cleaner on my plastic valve covers. I get everything squeaky clean and oil-free. Depending on design it may be advisable to add a few dabs of silicone in a few critical spots (without clogging oil openings).
Over time, valve cover gaskets may shrink a little and also get hard and brittle due to constant heat and cold cycles.

 

[1 FMF]

depends on the gasket,
cork, rubber, plastic, stamped steel with rubber liner or nitrile?

if it's a plastic type, or other than cork, and has hardened at all then it'll leak. Valve cover gaskets on '89 7.3L diesel were like that, when I pulled them out they were all hard, brittle, and in many pieces. I prefer the traditional cork gasket with a dab of permatex to hold it in place on the valve cover when putting it on, cheap and dependable.

 

[moribundman]

Actually, my six-banger requires a dab of silicone on both sides of the front and rear cam bearing where the VC gasket sharply angles.

I totally forgot about cork gaskets! The ones on my Buick and Chevy were always wet! I don't think it was due to the gasket material, though. Cork may well be superior to synthetic gasket materials in this application. For example, hemp is vastly superior to teflon tape in plumbing.

 

[Drew99GT]

Mori hit the nail on the head. Many 4 bangers require silicone across the camshaft plugs or next to the distributor to seal properly. Check a repair manual for exact details.