Head. Not the good kind.
 

felpro gasket. what's the reason for that crappy finish to chip off?

That coating just sticks and then it pulls off when you remove it.

You weren't planning on reusing the headgasket were you?

Yup, that's normal.

No I pulled it cause 4th cylinder was leaking coolant I'm guessing from that spot. The pieces missing were nowhere to be found and not stuck to the head or block.

You blew your head gasket, lol

no shit. I've never seen a coolant passage get blown out like that. Was curious if there is anything i should do differently since I only have 150 miles on that headgasket after a rebuild. Torqued my arp studs to 65 ft/lbs per general consensus on the arp head stud thread/flying miata. Head and block are machined and within spec.

possible your coolant system had air pockets still, under boost this could lead the HG failure.

Hello everyone....

Is there a different finish between #4 and the back of the head?

thank you. this is more along the lines of what I was looking for. If what you say is possible and correct this could have very well caused it. I let it run for a while and burped it but my reservoir needs to be replaced and I wouldn't be surprised if it sucked air.

I've only seen head gasket failures from overheating. I don't doubt there are other possibilities like detonation. Has anyone else had personal experience or seen this on their car?

yeah curly some chump at the machine shop lightly scratched the head on the back so it was cleaned up with a very fine stone. It is in good shape and perfectly flat. I trust my machine shop guy and any other machine shop guys can chime in here and hopefully back that.

yes I've seen it on a perfectly assembled and perfectly running car.

replaced it and it ran like a champ. absolutely nothing else was done, just a simple swap.

So yeah, like I already said nothing looks outa the ordinary, check everything over replace and try again
you mean just that one part? EWWW

I don't care what the guy says, I'd still be very very paranoid about that

I was so I had my uncle who is a retired calibrator for raytheon measure it. He gave it his approval and since he calibrated machines making missile parts and such for 30 years i trust him too.

Also my machine shop guy is a very honest and precise guy. because of it he charged me nothing and promised if I had problems he would replace and install it at no charge. Said he would put it on his car even and not think about it. Edit: also the stone marks are not just in that spot they are all over. It's across the whole head. The head was warped slightly when i took it in and he took it down accordingly.

Im trusting what you said about replacing it and being fine I just wanted to show pictures to see if anyone else had any similar experiences.

I've used one of those stones before. For a lot of stuff. You could use it for 24 hours straight on a head and take of maybe .001 or .002" max. They do nothing. You'd have a mirror finish by then though. That's probably why it looks discolored.