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Old 05-12-2022, 01:27 AM
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Default Valve Cover Gaskets

I got those fancy, blue, about 1/4" thick gaskets for my valve covers a while back. Now that the engine is running it's leaking pretty badly.

What I find strange is I snug them down, run the engine up to temp doing other things and I can get another 1/2 turn out of the bolts very easily ... this has happened about 3 times now. Does it take that long for these thick soft gaskets to compress?

Covers are OEM, the bolt holes were worked back flat and the lip is in good shape. I am using flange head bolts (similar to stock except larger flange) that pull nicely on the vertical walls of the cover instead of bending the lip.

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Old 05-12-2022, 06:26 AM
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I have found early on that the thicker the gasket. The more I had to jerk around with them!

I then went back to cork gaskets with sealing smear of form - a - gasket on each side, and presto no leaks!

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Old 05-12-2022, 07:37 AM
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Presently have Cast M/Ts to avoid the sheet metal flex. Yet,
Presently have a new repop Chrome "GTO" VCs with the 5/16 cork that which i RTVd them to the VCs and set dry on a set of Heads to cure and imprint the cork.

Still on (the shelf) and did have to inspect the insides 1-day and the bolt TQ felt fine (house temperatue only), and ready for my intemded VC swap some day.

There are steel extenders for the VC bolts to improve clamping distro for these stamped steel VCs. I might need em, before i know i need em.

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Old 05-12-2022, 01:17 PM
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I'm going to give these a bit more time ... then back to cork if they don't work out.

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Old 05-12-2022, 01:39 PM
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neoprene gaskets siliconed to a flat cover no silicone between head

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Old 05-12-2022, 03:17 PM
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Pretty sure I didn't silicon them to the cover ... and pretty sure they are neoprene ... kind of that foamy "wet suit" feel.

Last round of tightening them seem to be as far as they are going to go. Cover lip still isn't distorted and I don't have the gaskets squeezing out of place or anything.

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Old 05-12-2022, 05:06 PM
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I have found the 5/16 cork to be the best.I glue them to the covers with Hylomar and just a light smear of grease on the head side of the cork.Tom

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Old 05-12-2022, 10:00 PM
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Tom

First I've heard of Hylomar.
I've noticed there are different model numbers, colors, cans, tube etc.

So which Hylomar are you using or referring to?

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Old 05-12-2022, 10:12 PM
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The one in the tube,blue color and does not setup hard.EZ to clean.Been using it for years.Tom

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Old 05-12-2022, 11:22 PM
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Hylomar is good stuff. Invented by Rolls-Royce for use on jet aircraft engines. PRICED like it's aerospace-grade, too.

Far as I'm concerned, Gasgacinch does 95+ percent of what Hylomar does in automotive applications, at 1/10 the price.

https://www.amazon.com/JEGS-440-B-Ga...=1GHZLSNXEXZT9


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Old 05-13-2022, 07:02 AM
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FWIW - I also had issues with the thick 5/16” cork gaskets compressing quite a bit and leaking over the first several heat cycles. I had the best luck with the thin steel reinforced Viton gaskets that BOP sells. They sealed very well and did not continue to compress after initial install.

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Old 05-13-2022, 07:35 AM
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Quote:
Originally Posted by PDC View Post
FWIW - I also had issues with the thick 5/16” cork gaskets compressing quite a bit and leaking over the first several heat cycles. I had the best luck with the thin steel reinforced Viton gaskets that BOP sells. They sealed very well and did not continue to compress after initial install.
Hmmm, that sounds pretty good. I think old cork VC eventually fails ( splits, crumbles, hardens) from the oil soak & heat.

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Old 05-13-2022, 09:32 AM
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Quote:
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I have found the 5/16 cork to be the best.I glue them to the covers with Hylomar and just a light smear of grease on the head side of the cork.Tom
This ^^^^

I also do this on the solid lifter cars and can remove the covers to check lash once a year and just reuse/reinstall several times over a period of a few years and many thousands of miles, and they still don't leak.

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Old 05-13-2022, 10:54 AM
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Quote:
Originally Posted by tom s View Post
I have found the 5/16 cork to be the best.I glue them to the covers with Hylomar and just a light smear of grease on the head side of the cork.Tom
I also use the 5/16" Cork Gaskets but because I do not try to be original on my Solid Lifter Engine for many years, I USE ALLEN HEAD SET SCREWS IN THE HEADS (LIGHT PERMATEX ON THE BOTTOM OF THE THREADS IN THE HEADS).

And then I use matching Nylok nuts on the set screws. The set screws stay in place, the nuts JUST snug the cork gaskets slightly, and I never have valve cover leaks. Gaskets look like new and have been on the engine 10 years.

Valve covers come off once a year for valvetrain inspection. With the new Rhoads/ Hydraulic lifter cam I might not check them again after the first year.

Tom V.

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Old 05-13-2022, 11:29 AM
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I use these on the race motor with sheet metal covers and on the street motor with cast covers. Put them on dry and never had any problem with leaks.

https://www.tinindianperformance.com...cover-gaskets/

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Old 05-14-2022, 03:41 PM
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Quote:
Originally Posted by dataway View Post
I got those fancy, blue, about 1/4" thick gaskets for my valve covers a while back. Now that the engine is running it's leaking pretty badly.

What I find strange is I snug them down, run the engine up to temp doing other things and I can get another 1/2 turn out of the bolts very easily ... this has happened about 3 times now. Does it take that long for these thick soft gaskets to compress?

Covers are OEM, the bolt holes were worked back flat and the lip is in good shape. I am using flange head bolts (similar to stock except larger flange) that pull nicely on the vertical walls of the cover instead of bending the lip.
Are those the ones with the steel core like the SBC gaskets?

I had problem with the neoprene cork. The only thing I found that adhered the to the chrome valve covers was 3M weatherstripping adhesive, even after sanding the valve cover flanges. I was always getting leaks from the gaskets sliding into the heads between the tabs.

I bought some silicone looking gaskets with a steel core a few yrears back that retain their shape plus the head mating surface actually had raised beads around the outside and inside edges that keep the gasket located. Never had a leak again. I don't see them for sale anywhere now for Pontiac, though.

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Old 05-14-2022, 04:15 PM
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Quote:
Originally Posted by racegto65 View Post
I use these on the race motor with sheet metal covers and on the street motor with cast covers. Put them on dry and never had any problem with leaks.

https://www.tinindianperformance.com...cover-gaskets/
TIP gaskets @ Kauffman now.

http://www.krepower.com/Pontiac%20Gaskets.htm

I’ve run a black rubber gasket forever, they are still on my Moroso gold covers from the eighties. Glued to the covers with black weather strip adhesive. I’ve never changed them and they have never leaked. Of course I have no idea who made them. Solid roller motor so the covers did get removed frequently.

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Old 05-14-2022, 06:35 PM
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Rubber gaskets always leak on Pontiac engines. The factory covers are too thin and have too much span between fasteners. Not a shining moment in Pontiac design. I have had the best luck by far with cork gaskets. Mr. Gasket sells a really nice set in the Ultraseal line. It has a paper thin coating of black sealer sprayed over the cork so it doesn't wick too much. I tack them in the cover and put nothing on the head side. That's my best recommendation. Anything silicone or rubber leaks for me, I don't use them. Good luck.
https://www.speedwaymotors.com/Mr-Ga...CABEgLXzvD_BwE


Last edited by mgarblik; 05-14-2022 at 06:41 PM.
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Old 05-15-2022, 02:53 AM
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I'm old enough to remember that we put any type of gasket on the valve covers and it seemed like they would seal for the life of the engine. Now I spend a fortune on them and no matter what type or style I purchase they have to be tightened every few months until they eventually fail. Maybe a clandestine plot to increase valve cover gasket sales?

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Old 05-20-2022, 07:41 AM
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Quote:
Originally Posted by Formulas View Post
neoprene gaskets siliconed to a flat cover no silicone between head
Along with glueing the rubber gasket to the cover, I also put a light film of wheel bearing grease on the gasket side that mates to the head. After fighting valve cover leaks for years this method worked for me.

I got this tip from somebody on this forum.

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