Valve Cover Help

[ARAMP1]

My old stock stamped valve covers on my 454 were leaking a bit and instead of just replacing the gasket, I decided to buy a set of O ring type valve covers.

I bought them on e-bay for around $20 which is what used sets seemed to be going for. Anyway, they came with the used gasket (which looked to be in good shape), so I decided to put them on and they leaked like a sieve. Okay, I decided to buy new gaskets. That helped, but they were still leaking. Next step was to use some RTV. I used a thin coat and again it helped, but the problem was still not fixed. Alright, if a little is good, more is better. I decided to cake on the RTV and they’re still leaking.

The valve covers are not cracked or warped at all and they heads look normal. Any ideas what I could be doing wrong?

 

[Hogback Fabrication]

How well did you prep the head surface and valve cover surface? Probably your problem.

 

[ARAMP1]

I definitely cleaned all of the old gasket material off. Other than that, there isn't much prep.

 

[3 on the tree]

Scrub the mounting surface down with carb cleaner, to get rid of oil residue, then try again.

 

[Hogback Fabrication]

If you don't use a solvent that doesn't leave a residue (brake cleaner, carb cleaner, laquer thinner, etc.) you will have trouble with RTV.

 

[ARAMP1]

Sorry, should have specified. I did use brake cleaner. The mating surfaces are clean enough to eat off of yet it still leaks. Are there some heads/covers that weren't compatable?

 

[Dr. Morgenstern]

What year are the heads? Newer cast aluminum gm covers don't work on the Mark IV heads unless they've had some milling done to the gasket mating surface.

 

[blazinzuk]

Have the bolts been tightned down really tight a couple of times. That can ruin the valve covers. It honostly sounds like you may have some warpage in your valve covers. Sometimes its really hard to see.

 

[ARAMP1]

What year are the heads? Newer cast aluminum gm covers don't work on the Mark IV heads unless they've had some milling done to the gasket mating surface.

If this is true, it would explain it. The truck is a 1990 with the origional heads and the covers are from a 94-95 (I think). Can you explain the milling?

 

[BadBob]

I've had no issues at all with the GMPP covers on my 85.