These darn old V-8 engines (mine a 383) are always leaking oil. Most common place is out the valve covers. My valve cover gaskets were replaced not to long ago with cork gaskets. Do rubber gaskets seal appreciably better?
What is the best valve cover material?
- Thread starter Henrius
- Start date
I've always used the Felpro FEL-1612 (or the 50145) rubber coated fiber. Never had leaks - just don't over tighten.
Last edited:
3175375
Senior Member
The EASIEST way to keep a metal valve cover from leaking, AFTER the flange is tapped back to "flat", is to prevent the oil wicking through the gasket itself! THAT's where the seep/"leak" comes from and why it happens repeatedly.
My late machine shop operative noted that one time. I had told him about a friend in our Mopar club who was complaining about a brand of motor oil that he started using, rather than the common Pennzoil. He complained that that oil made every gasket on his 383 leak. I found that curious as I used a similar oil with no leaks. Then Tommy told me what caused the leaks in the first place. The lighter parts of the oil are absorbed by the cork in the gasket, even when compressed. No big deal until the oil gets absorbed by the cork until it gets to the outside edge of the gasket, where it manifests itself as "a leak". Once started, more torque on the hold-down bolts MIGHT slow it down, but not stop it.
So, next time I needed valve cover gaskets, I got some high-quality rubberized cork gaskets. I then took some high-heat silicone sealer (the thicker version) and put a thin coat of it on the gasket, top bottom inside and outside, smearing it with my index finger (wiping it off my finger afterward). Just a thin, consistent coat. Let it cure overnight, install the next day. Ensuring the valve cover flange is smooth and flat, then using "snugging" levels of torque on the hold-down bolts. Everything stays DRY for well past 100K miles, with no way for the oil to penetrate into the cork, so no wicking action, and what comes after that.
Consider . . . a new engine usually has some engine paint on the outer edge of the gaskets from the factory. No leaks until that paint might crack from somebody torqueing the valve cover bolts "for good measure".
In the 1960s and 1970s, every mechanic had their own "secrets" to get a better seal. Some included "glue", but that old yellow weatherstrip adhesive needed a jack hammer to get off well enough to put a new gasket on the valve cover, by observation. I knew there had to be a better way, but that later included tapping the vc flange flat against an anvil. So I tried my silicone sealer trick and it worked great. Easy to remove, if needed, too. Might even allow the treated gasket to be re-used!
KEY thing is to let things cure overnight before installation. NOT an orientation to glue things together, but just prevent the wicking from happening in the first place. So a "dry" installation of sorts, in that respect.
Just MY experiences,
CBODY67
My late machine shop operative noted that one time. I had told him about a friend in our Mopar club who was complaining about a brand of motor oil that he started using, rather than the common Pennzoil. He complained that that oil made every gasket on his 383 leak. I found that curious as I used a similar oil with no leaks. Then Tommy told me what caused the leaks in the first place. The lighter parts of the oil are absorbed by the cork in the gasket, even when compressed. No big deal until the oil gets absorbed by the cork until it gets to the outside edge of the gasket, where it manifests itself as "a leak". Once started, more torque on the hold-down bolts MIGHT slow it down, but not stop it.
So, next time I needed valve cover gaskets, I got some high-quality rubberized cork gaskets. I then took some high-heat silicone sealer (the thicker version) and put a thin coat of it on the gasket, top bottom inside and outside, smearing it with my index finger (wiping it off my finger afterward). Just a thin, consistent coat. Let it cure overnight, install the next day. Ensuring the valve cover flange is smooth and flat, then using "snugging" levels of torque on the hold-down bolts. Everything stays DRY for well past 100K miles, with no way for the oil to penetrate into the cork, so no wicking action, and what comes after that.
Consider . . . a new engine usually has some engine paint on the outer edge of the gaskets from the factory. No leaks until that paint might crack from somebody torqueing the valve cover bolts "for good measure".
In the 1960s and 1970s, every mechanic had their own "secrets" to get a better seal. Some included "glue", but that old yellow weatherstrip adhesive needed a jack hammer to get off well enough to put a new gasket on the valve cover, by observation. I knew there had to be a better way, but that later included tapping the vc flange flat against an anvil. So I tried my silicone sealer trick and it worked great. Easy to remove, if needed, too. Might even allow the treated gasket to be re-used!
KEY thing is to let things cure overnight before installation. NOT an orientation to glue things together, but just prevent the wicking from happening in the first place. So a "dry" installation of sorts, in that respect.
Just MY experiences,
CBODY67
I use fel-pro cork valve cover gasket with no sealer and no leaks. Take you "saturated" cork gasket and cut it with a razor blade, they are dry inside.
Sealing these things are not as simple as they seem.
After 50+ years the valve covers are not straight anymore. They need to be tapped out with a hammer on engine side and a block of wood supporting from the topside.
Then they need to be clean, really clean. Clean them again. Head and valve cover.
Now use fel-pro cork gaskets VS-13379. $9.91 on rockauto. Snug them down and wait. Don't start the engine for 2 days. Every 12 hours or so snug uo the bolts, they will be loose. Then run it and get it hot, let it cool and next day snug the bolts again. And try this again after more driving and cooling cycles.
You can't just put "the best" gasket on a warped valve cover, on dirty surfaces, tighten the bolts once and be done. It will leak
Sealing these things are not as simple as they seem.
After 50+ years the valve covers are not straight anymore. They need to be tapped out with a hammer on engine side and a block of wood supporting from the topside.
Then they need to be clean, really clean. Clean them again. Head and valve cover.
Now use fel-pro cork gaskets VS-13379. $9.91 on rockauto. Snug them down and wait. Don't start the engine for 2 days. Every 12 hours or so snug uo the bolts, they will be loose. Then run it and get it hot, let it cool and next day snug the bolts again. And try this again after more driving and cooling cycles.
You can't just put "the best" gasket on a warped valve cover, on dirty surfaces, tighten the bolts once and be done. It will leak
SportFuryman
Member
Good gaskets and aluminum valve covers…never will leak again
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