poll on cometic hp head gaskets

[AL92]

Never done a poll so hoping this works out..Basically are you using a cometic hp and has it failed and second question are you using copper spray or hylomar on it?

 

[project_tsi]

Yes I had a Cometic fail me last year. No, it was not sprayed with anything. It had ARP studs and was properly torqued down/installed. However I can't place all the blame on the HG. It didn't like the occasional spurt to 28 psi and also the head and deck surface wasn't the absolute best. It was ok, but it I guess it wasn't good enough.

 

[GVR4592]

25 psi daily and 30 psi accidentally a few times on a stock gasket for a year and then on a Cometic for about 7 months. No problems. Almost any head gasket will hold 30 psi under the proper conditions. The key factors for a reliable metal head gasket are glass smooth surface on the head and block, properly torqued fasteners, and absolutely no detonation. Detonation is the number one killer of any head gasket.

 

[DSMu4ia]

Cometic HP here.

Let go at 18psi and c16. No knock.

Roughly 1200 miles on it.

 

[AL92]

I only have 300 miles on new 2.4 with the cometic hp. It was sprayed with copper spray.
I have only boosted to 13psi or so on my big fp3065. So far no problems. I did a retorque after a few heat cycles it was ok took them to 90ft pounds heard even 95 is fine.
I may do one more retorque as a double check.

So far no white smoke .I do have an oil leak problem that am trying to figure out but dont' think its the head gasket. Only in one spot it seems. I would think head gasket would leak in a few places if it was leaking or leak coolant too? My oil is perfect ,antifreeze is perfect.
So far so good. Be upping the boost to 15 to 20psi as soon am done the 500 mile break in on the clutch.

 

[talonTSIDriver]

There are numerous threads that explain not to spray anything on the MLS head gasket, the Cometic especially. Reason is the MLS are not meant to have any spray put on them is because you have an iron block with an aluminum head. Both at which expand to heat at a different rate. The purpose of the MLS gasket is to act as a barrier and allow the head and the block to move at its own rate. If you spray the MLS HG, now you just defeated the purpose. Key is you have to have the head and block perfectly surfaced like GVR4592 stated. Just do a search of it and you will fine a few really In-Depth articles on this.

 

[AL92]

I talked to many many people running the cometic and many with good results like many 30psi type runs had used copper spray.
Yes it says not to on the cometic site but I talked to some of their techs and they said it couldnt' hurt!
So right from them. I guess the test is how long mine lasts.I plan on think mits raliart its called for my 2.4 if have any problems at all with the cometic headgasket.They also I think don't make the hp anymore.

My head and block were smooth but not sure the RA no one had RA Tester in my city of over 200,000 people. Cometic said easier check is simply to run fingernail across the surface and if it catches its too rough.

I am not in a postiion to say how my cometic is going to hold up since only running 13 psi or so right now. But I would not be worried about spraying the cometics and it might make the difference.

 

[DSMu4ia]

The big question is why mine popped.

Perfectly decked head and block, fairly safe tune, etc etc.

Guess I'll find out in a day or two when the head comes off.