I just put my motor back together. Part of the head work included resurfacing. They shaved .005". No noticable cracks or iregularities. Block deck was level and smooth.
I used a .054" Cometic Head Gasket. Arp studs torqued to 85lb/ft.
Engine ran fine. After a couple days I smelled coolant.
I looked around and could see where coolant was leaking under the exhaust manifold, at the head gasket on the tranny side of the engine. I pulled valve cover and double checked torque, still good at 85lb/ft. No water in oil or vise-versa, no steam out exhaust.
I finally pulled head today. Block looked good, flat, even. I could see where gasket had mated accross entire surface.
On the head side, I could see where the head gasket wasn't mated (no head gasket residue), like it was steam cleaned away. Head is flat, even, unwarped.
I'm at a loss.
Here's what I'm down to:
Maybe an invisable crack.
Maybe bad head gasket.
Anybody else have any ideas?
I'm taking the head to the machine shop tomorrow.
I also have a spare stock head, but I'd like to use the moded head I have (+1mm, ported/polished, springs, retainers, etc..).

 

if u have a true bar and feeler guage use it to ck for block and head warpage, of course u can't see the subtle dip on it's surface..

 

Were you boosting the car heavy or just breaking it in easy ?

 

I was keeping the boost under 20, with afr 11:1. Didn't really push it hard.
The only way I know to find a crack in aluminum is with dye, (which I don't have).
I'll see what the machine shop says? I'm taking the head gasket with me too.
I did notice the resurface was visably ruff. I couldn't feel the marks with my fingers, but when I ran a pair of tweezers accorss it, I felt the vibration of ridges. Nothing you could see under a straight edge. I figured the head gasket would fill in these ridges/valleys, which are surely in the .0005" catagory.
I'm leaning more towards a crack, not visable.
The water leakage was very minor, but it was leaking.

 

Did your plugs have coolant residue on them?

 

Many people with DSMs who use a Cometic gasket use copper spray on it to help the seal. Did you choose this HG because you were concerned about the head being slightly shaved?

 

one of the better head gaskets i have seen is a factory gasket, many will argue but they are pretty tough gaskets.

 

Had head checked, it's flat and uncracked. I'm going to use coppercoat on a stock gasket. We'll see?

 

I just had my headgasket pop on me too, it was also a cometic. I have been doing research and it seems that the cometic headgaskets need a perfectly smooth and straight surface to properly seal. Some of the high hp guys using this headgasket actually hand lap the surface of the block with very fine grit sandpaper until it looks like glass and it seems to be working for them.

I am going to go back to a stock gasket with coppercoat this time after I take the head to the machine shop for them to look it over again. From what I am told the stock gasket is a little more forgiving to minor surface imperfections than the cometic but metal headgaskets in general need a very well prepped and straight surface to seal correctly.

 

What RA level of smoothness was the head finished to? If it wasn't milled correctly for the gasket to be used it might not seal completely.

EDIT: What Fas4dr said...

 

guys i had the same problem an hks 1.2mm head gasket cure it.

 

This is supposedly prepped for a Cometic head gasket.

 

If in fact the Cometic gasket is a race-ready gasket you should've used a sealant of some form to prevent any leaks from the water passages. This is normal practice specially when using these types of gaskets (race). Some use anti-seize, some use Hi-tack spray sealant, etc. The main purpose of these types of gaskets is to create a good seal for the combustion chamber, the rest (water,oil) passages are minor and dont hold too much pressure. Why did you even try an aftermarket HG when the stock one is as bulletproof as they come? Also, be carefull not to overtighten the head bolts since higher torque is not better seal. Too much torque and you actually distort the gasket material. I suggest no more than 75lbs, and I always use only 70lbs with zero problems.

 

I put mine together today with a stock head gasket and coppercoat at 85 lb/ft. I'm going to run to tomorrow with only distilled water for 15-20 mins then re-torque to 85.
After that I'll add water wetter, (no need for antifreeze here, cools better).
Not sure of RA smoothness, but not like a mirror. Neither is the stock head.

 

Got it running today. No leaks so far. Runs great. I haven't really goten on it yet. I want to do a few heat cycles then recheck torque.
I'm thinking if I would have used coppercoat on the Cometic, it wouldn't have leaked.