Cast Aluminum Valve Covers Leaking

-
G

gzig5

Well-Known Member
Joined
May 3, 2018
Messages
2,853
Reaction score
3,840
Location
Mequon, WI
Had a grungy set of M/T valve covers on the engine and replaced them with the new polished Mopar ones I got with the car. The old ones never leaked, they are just ugly. Used new cork Fel-Pro gaskets and ARP bolt kit. First, it took several tightening cycles to the bolts to hold torque as the gaskets seated. Now the bolts stay tight, but I've still got a leak at the rear of the head. The leak runs down the block and drips on the headers and it's getting anoying seeing and smelling the smoke. Haven't pulled them back off yet, but I looked at the old covers and saw that one had a black rubber gasket and the other had two cork ones siliconed together. Obviously they had issues in the past. What is the formula for success here? I don't want to glue the cover onto the head but some silicone between the gasket and cover should help?
 
Using some RTV on the cork gaskets both valve cover side and also head side is the best idea. Take cover off. Clean channel/lip gasket sits on. Put a thin rtv line down and press gasket into it. Then put another thin of RTV on the gasket and put them on head. Bolt it down. Let it sit about 30-60 minutes before starting it.

Riddler
 
If they are stock heads with "as-cast" valve cover rails you'll probably never get cast aluminum valve covers to seal. The surface on the heads is nowhere near flat. Steel covers bend and conform to the head surface, while the cast aluminum ones do not bend.
 
gzig5 said:
Had a grungy set of M/T valve covers on the engine and replaced them with the new polished Mopar ones I got with the car. The old ones never leaked, they are just ugly. Used new cork Fel-Pro gaskets and ARP bolt kit. First, it took several tightening cycles to the bolts to hold torque as the gaskets seated. Now the bolts stay tight, but I've still got a leak at the rear of the head. The leak runs down the block and drips on the headers and it's getting anoying seeing and smelling the smoke. Haven't pulled them back off yet, but I looked at the old covers and saw that one had a black rubber gasket and the other had two cork ones siliconed together. Obviously they had issues in the past. What is the formula for success here? I don't want to glue the cover onto the head but some silicone between the gasket and cover should help?
Click to expand...

Are you talking small block or big block???
 
I use a thick fiber-type gasket (black, non cork) glued to the BB cast cover with weatherstrip adhesive, iron heads. No leaks (yet).
 
You should also check to see if the valve covers are hitting the top edges of the intake, where the intake bolts to the heads. Sometimes, the notches in the valve covers that are made to clear the intake runners need to be deepened slightly.
 
The thick fiber ones will seal or the rubber ones with a steel core. Its all I use anymore, never have an issue like the cork ones do.
But yeah, the factory rail was as cast so you may have an imperfection on that head. Its a shame they didnt machine that surface but back then an oil leak was not a huge issue.
 
its hanging up on the intake runners most likely. They all do that. 2 fixes: one is to mill the valve cover lip around the intake runners for clearance. 2 is to run 2 cork gaskets cemented on top of each other to give you about 1/4 gasket thickness. That should raise the lip off the runners.
 
X2 on the rubber steel core gaskets. Had heck of a time getting corks to seal on my dart and this was after modding for clearance.Changed to rubber/steel core units.
No leak issues after 3 yrs.
They are pricier but you can get a good set for $20.
Worth every penny.
 
Might be wise to more closely at source of leak. Sometimes the gasket is fine but the leak is coming from the v/cover bolts. Simple fix- remove the bolt, RTV it, reinstall.
 
Murray said:
Might be wise to more closely at source of leak. Sometimes the gasket is fine but the leak is coming from the v/cover bolts. Simple fix- remove the bolt, RTV it, reinstall.
Click to expand...

Looks like I'm getting a little of that on a couple bolts but I think that stopped when the gaskets took a set. Definitely not the source of the big leak though. Will have some time to play with it over the weekend and see what's what.

I'll verify I'm not hitting the intake too. Looked like it had enough room when mocked up but stuff moves when it's tightened. Really hoping it isn't the rear China wall from the intake change . Fingers crossed.
 
I like the fel-pro neoprene valve cover gaskets...

Look it up as a 64 - 67 273 that had adjustable solid lifters and you will get the proper part #....

FEL-PRO VS13395R
 
You must log in or register to reply here.
-

Back
Top