Valve Cover Gaskets - Cork or Rubber?

[Fred Zwicker]

I have an original 1955 Pontiac Safari wagon with an original rebuilt V-8 engine and in detailing the engine, we removed the valve covers for painting. These covers had cork gaskets and did not leak. All of the old cork was carefully removed and it was stuck tightly to the inside of the valve covers in most places. We ordered new gaskets, but they were black rubber (Fel-Pro).

1) We installed them carefully, but they both leaked.

2) We removed them and carefully applied black silicone sealer to the rubber, including around the 4 bolt holes. All metal surfaces were spotless. They both still leaked.

3) We removed these and started all over with a new set of the same black rubber gaskets (Fel-Pro). This time we were very particular and double-checked to be sure that the inside surfaces of the valve covers were dead flat. We used a light coating of gasket shellac to hold the gaskets in place to the covers only while installing. We did not use any silicone this time and we added a set of the flat metal plates at each bolt to distribute the attachment more evenly. At startup, everything looked good until we took it for a short drive. More leakage.

*Note: We did not over-tighten the bolts, snugging them up and tightening about a half turn, which seems to be the proper procedure.

I am now wondering about the advisability of using rubber gaskets for this application? I just ordered a set of cork gaskets and that will be our next move. We are getting frustrated. When we install the cork gaskets, what type of sealant (if any) is recommended? (One side or both sides?). The valve covers are original, are not rusted, and appear to be in perfect shape.

*Note: The oil was just changed prior to all of this at a Quick Lube and they used 5W30 oil and it was marked, "Semi-Synthetic". I heard that synthetic oil has a tendency to leak, but do not feel this is the entire problem, as leakage is considerable. We plan to change back to a heavier conventional oil as soon as we can get the valve covers properly sealed.

Any ideas on this? Thanks,

Fred

[Larry Schramm]

I would use the new gray RTV that GM uses. I have used it with great success. It comes in a Loctite blister pack at the auto stores.

[Guest]

Fred, I always use cork gaskets. The pressure distribution tabs are a good idea, although in 45+ years of working on Pontiac's have never used them. I use aviation permatex on the valve cover side only and never get leaks this way. I did have a valve cover leak on my old 59 Catalina back in 1967 and that was because I used the rubber type and after the same struggles your having today I went back to cork. I would check the head surface and also the valve cover for warpage again.

Don

[TexRiv_63]

Fred,

I have had better luck with the cork gaskets. The neoprene type likes to move around too much but it is better if you need to remove your valve covers on a regular basis. I have used Olson gaskets on my old cars, they supply a gasket that appears to be a rubberized cork? I glue the gasket to the valve cover with Permatex #2 or High-Tack, then I apply a coat of wheel bearing grease to the head side, this seals but still allows removal. Good luck!

[Bhigdog]

Cork is better!..............Bob

[Ben Bruce aka First Born]

Fred, I had a similar problem with the pushrod [side ] cover on my Buick. The "rubber" gasket was actually wicking oil through it. Used cork. No more leak. I purchased a roll of cork and cut my own to save time and $$.

Ben

[Caddieman53]

I agree with the rest Fred. I used the cork on my 53 several years ago now and have never leaked a drop.

Paul

[Mark Shaw]

I use cork gaskets and stick-em to the head. When I remove the cover the gasket provides a lip that keeps the residual oil from making a mess of the engine.

[Guest Earl]

You can't get neoprene gaskets to work in player pianos either... And that stuff tends to shrink with age as well. It's good to know it doesn't work well in cars either!

[Fred Zwicker]

After 3 tries with the rubber valve cover gaskets, finally was able to obtain a set of cork gaskets (Fel-Pro brand, the same as the rubber ones). Using the same methods as used previously, installed the cork gaskets and had perfect results - NO leaks. I can't figure out why they even sell the rubber gaskets, although one friend who used to drag race liked the rubber gaskets as were easier to remove and replace for adjustments. I guess a little oil leak didn't bother him.

Next is to remove the 5W30 oil semi-synthetic oil and replace it with 10W40 non-synthetic oil to quiet down some valve clatter at startup, which stops completely after warmup. I heard that synthetic oils tend to leak as well. This will be done tomorrow, as we are getting the car ready for the September 19th Glenmoor Concours show. See www.glenmoorgathering.com

Here is a picture of the car.

Fred

[Guest]

Fred, I'm glad everything turned out OK for you. Great looking Safari !!!

Don