Pesky valve cover gaskets

[Charles P.]

I have reinstalled a pair of stamped steel valve covers on an L-48 350 with cork gaskets. They seem to be sealed except for around several of the 4 bolts on each which ooze occasional drips of oil. Does anyone know of any cures? Thanks.

[Joe L.]

Re: Pesky valve cover gaskets

I have reinstalled a pair of stamped steel valve covers on an L-48 350 with cork gaskets. They seem to be sealed except for around several of the 4 bolts on each which ooze occasional drips of oil. Does anyone know of any cures? Thanks.

Charles----


First of all, the covers need to be "flat" in the area of the bolt holes. If the steel surrounding the hole is "pulled down" (as it usually is), you need to flatten these back to near original configuration. It's easy to do with a hammer.

Secondly, I have had better sealing luck with Fel-Pro Cork-Lam gaskets than any others. However, these gaskets are a little thicker than stock and this might be discerned if you have the car judged.

Third, apply only the proper torque to the valve cover bolts. Excessive torque will distort the gaskets and, sometimes, cause a leak.

[Charles P.]

Re: Pesky valve cover gaskets

I was thinking some Permatex applied discreetly around the bolts would work. The experiment I tried on one ide does not seem to have worked however. I will try the Fel Pros next and check the covers for true.

[Martin N.]

Re: Pesky valve cover gaskets

CHARLES-
Joe is absolutely correct about having your bolt hole areas perfectly flat before installing your gaskets. When I did mine I also used the gaskets he suggested, clear RTV along the (sparingly) bottom edge and torqued them to spec. After a 1/2 hour run time and the engine cooled, I re-torqued them and they've been leak free ever since.

Marty

[John H.]

Re: Pesky valve cover gaskets

The primary leak path is between the cover and the gasket, not between the gasket and the cylinder head. After ensuring that the cover's sealing surface is nice and flat as Joe noted, I run a thin bead of Permatex "Ultra-Copper" RTV around the cover's seal surface (with a little ring around each bolt hole), apply the gasket, and let it sit overnight. Then apply a thin film of oil on the head side of the gasket, and install the covers, snugging the bolts to no more than specified torque. After a few hours of run time, check the bolts for torque again, as the torque will relax a bit as the gaskets absorb some hot oil.

This approach will allow you to remove the valve covers when needed (valve adjustment) without damaging the gaskets; I've never had a leaker with this method, even with stock cork gaskets (although the Fel-Pro Cork-Lam gaskets seem to work best).