2 Cometic Head Gaskets Fail the Same Way

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Posted 08-08-2011 at 01:29 PM by VETDRMS
Updated 08-08-2011 at 08:19 PM by VETDRMS

As the title implies I just finished removing my 2nd Cometic gasket after it started to pressurize the coolant system.

The first failure happened at relatively low boost (24-25psi) and conservative timing for E100 (14* total, 7-8* @ 5000).

Both the head/deck were prepped for MLS to a mirror finish. The block deck was checked for flatness. I am using A1 H11 studs torqued to 95 ft/lbs (30-60-95).

The first gasket was a Cometic 87mm (.066" thick), the second gasket was 87.5mm (also .066" thick). Copper spray was used on both.

The first time it failed it was mostly at the back of cylinder #2, right in the middle. After cleaning the deck surface it also leaked in the front of #2 and the front/back of #3. Each point of failure was directly in the middle and directly in line across the cylinder (front to back).

Upon the first disassembly there was some overhang of the gasket into the chamber due to too much material being taken off when deshrouding the valves. The head was welded up, seats replaced, and re-machined.

It failed at the same boost/timing on the 2nd gasket. It held fine at 22psi. It failed in the same spots as well.

I will post up a solution when I find one, hopefully the third time will be a charm.

Posted in DSM Project Car/Build Updates

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Comments

	On the new one, don't use the copper spray. Cometic says to install the gasket dry. Give that a shot and see what happens. And if you think about it... what would the point be of getting both surfaces to a mirror finish and then spray something on it? Good luck!
	Posted 08-09-2011 at 09:02 AM by 95talongirl

	I hate to say it but... No more Cometic's man!!! You will be in the same situation again.. I have pics of mine somewhere.. Failed right behind the second cyl. As well... I guess they work great on n/a but they just do not hold up to boost well at all...
	Posted 08-09-2011 at 10:23 AM by Djsniperwolf

	That's weird to say that as a friend of mine with a 10-sec, 500HP turbo 2.4L (GT35R running about 30-35psi) Daytona has used a Cometic gasket for years with no problems. He also installed his dry.
	Posted 08-09-2011 at 02:00 PM by 95talongirl

	I might be trying a Fel-Pro Permatorque this time.
	Posted 08-09-2011 at 02:05 PM by VETDRMS

	I have heard nothing but awesome things about the Permatorque Head Gasket. It is odd, as 95Talongirl states.. There are cars with proven numbers running these gaskets.. But.. I have heard of so many failures, I figured it wouldn't happen to me... It did...
	Posted 08-09-2011 at 03:57 PM by Djsniperwolf

	I would try a felpro composite. you have the studs for it. you can run up to 30psi on them
	Posted 08-10-2011 at 12:32 AM by ed1380

I installed my Cometic with copper spray, the head was rebuilt from SBR stage 2 and the surface was very smooth. Mirror finish but you could still barely see some milling swirl marks. Block I used the plastic yellow M3 prep wheel on the air dremel to clean. I was getting what appeared to be liquid in the cylinder 2 and 3. I retorqued it and it went away. I have been driving it on 27Psi for about 6 months now and no signs of a leak yet. The cooland is always full when I pull the radiator cap and check. No coolant in the oil and no smoke out the tail pipe.

Posted 08-11-2011 at 09:52 AM by BIGBLAZE79 BIGBLAZE79 is offline