Anyone ever blew a cometic head gasket

headslide

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Apr 15, 2015
Just asking curious if it can be done I had an issue Saturday made a pass car filled with smoke oil everywhere dead cyl and a pop pop pop used cometic with studs .they held good at 48 pounds I guess 49 was too much
 
I have replaced Cometics which were well below 40 psi boost.

The factory rated a stock head gasket at 22 psi, more than that you paid the bill!
 
worst part about blowing a cometic is you usually end up with a scoured trench on the head or deck or both , not to mention the stress put on rods .pistons crank and mains that needs inspecting .. thats when your simple headgasket change goes from affordable to time to re-evaluate your finances
 
Just asking curious if it can be done I had an issue Saturday made a pass car filled with smoke oil everywhere dead cyl and a pop pop pop used cometic with studs .they held good at 48 pounds I guess 49 was too much

No gasket will seal if the head lifts.

The Cometics often will re-seal when the head sits back down and you'll have a running car after the failure that can at least get back to the pits and get itself back up on the trailer.
 
When you blow a Cometic gasket you can rest assured you have probably killed a piston. The stock ones or Fel Pro equivalent would pop not hurting other parts.

Cometics, not so much.........
 
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Do this and they will hold to 51


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Had two let go so I pulled the engine and fixed it right the second time.

In my case it went to water on the same head.

Had the machinist take 3 thousands off the head and block to get then trued and have the correct finish to seal like they should.

They are picky and have to have the right finish on them to work.
 
They can blow. Boost itself doesnt blow a gasket. Many have run stock gaskets 30psi+. This is from a map sensor issue.
 

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That is the one downside of mls head gaskets. They won't blow like a stock or felpro gasket. You have a meltdown. So you really have to be on your game.
 
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