ITT we speculate why my head gasket failed (amateurish pics inside)
 

History:

I got the head gasket set through my friend (a mechanic) from worldpac. The branding on the package was "Elwis" or something like that and it was 35 bucks his cost, homey hookup.

It ran for about 200 miles. It always had a problem detonating that I never could fix even if I retarded the timing way too much. It would still detonate under high rpm high load. One day I popped the radiator cap while it was running and the water was gurgling and bubbling. I chose to ignore this and pretend I didn't see it knowing damn well what the problem was. Another day when I got home I heard a hissing sound and saw that coolant was squirting out from between the block and the head and at that point I knew it was over.

Anyway, I finally found time to pull the head tonight and inspect what was going on. See the pics below. I dont know if this failure was due to the detonation or the failure is what caused the detonation. I noticed that there are a lot of holes for the water jacket that are blocked off completely by the gasket.(Edit: compared this to an OEM gasket and they are the same, scratch this thought) I feel like this might have caused it to over-pressurize at that port in the bottom right corner and blow through the gasket but there are other failure points all around cyl #4. Pics:

Whole Shibang:
Attachment 188681

A couple of #4:
http://img.photobucket.com/albums/v6...r/DSC03097.jpg
http://img.photobucket.com/albums/v6...r/DSC03095.jpg

Failure spots clockwise starting at 11 O'clock:
Attachment 188682
Attachment 188683
Attachment 188684Attachment 188685

And a couple shots of the under side of the gasket:
Attachment 188686
Attachment 188687

Also I should note that a couple of the head bolts were not tight enough. They busted loose way too easily but they weren't any of the ones around the failed cylinder. This is definitely the last time i'll ever cheap out and re-use head bolts. Head studs all the way from now on.

I say shitty head gasket to begin with, that's a complete and utter failure all around, not just one or two places. If the head gasket doesn't compress properly, the head bolts can't stay torqued. They'll only stay torqued if there's still tension. A head gasket disintegrating below them will release some of that tension.

+1 for shitty head gasket, I almost want to say the material its made out of looks nothing like mine, but its been 2 years since I've had my head off.

Also, I'm reusing head bolts, no problems so far. They aren't torque to yield so they are reusable. Though I'm sure some ARP studs would be better.

Why would you not run a MLS gasket? Paper is for wiping your ass.

Cause it's $100+ vs $30.

That's what you get for a generic chinese part :giggle:
OEM or bust?

That really sucks though...yet scary at the same time to see how bad that HG failed.

Felpro MLS gasket is 33.97 at rockauto

Soundbite:
http://www.moviewavs.com/0094473955/...e/holdcall.wav

Head bolts are reusable if not damaged. Cheapo head gaskets are not a good idea, especially if increasing cylinder pressure or temperature above stock. You should carefully inspect the head and block mating surfaces at those failure points to make sure no damage occurred that might require light machining to regain "true."

Last HG that failed on me happened with a HG that looks similar to yours, not oem.

It failed in about 20 miles. I blame my torque wrench, I under torqued the bolts.

http://www.boostedmiata.com/gallery2...headgasket.jpg


I acutally think my HG is going bad right now, but htere is no MLS for a 1.6L thats as cheap as the OEM.

Ok, i'm going to say they were improperly torqued as well. I think though what might have happened is that I used too much oil when lubing the threads on the head bolts so that there was some still at the bottom of the hole that the bolts had to thread against and compress. Thus, incorrect torque numbers.

I forgot to mention that this is my GTX for whatever difference that makes, not my miata. I was worried that this was going to be a bitch of a headgasket job since the engine is the other way but it hasn't been bad at all. 1.5hrs to remove the head while kind of taking my time.

Also, importperformanceparts.net has Cometic gaskets for 79 dollars if you buy something else with your order. 89 dollars otherwise. I'm buying head studs and a cometic gasket for 200 bucks total.

Not only does that throw off bolt tension, but it can crack the block. Happened to more than a few BMW lumps over the years.

How much time and money has he spent replacing it the second time?

We use Cometic MLS gaskets for 1.6 motors, and OEM Mazda for 1.8 motors. No exceptions.

I've had no issues thus far with my cometic and ARP combo. Good choice anthony..

I just ordered a new Cometic gasket but the part number from the place I ordered it doesn't match the part number on Cometic's website. Would you care to share the part number for the gasket you guys use?

I just straight edged the block and head and it all checks out. I'm guessing this is due to improper torque or a failure of the cheap gasket or a combination of the two. I'm a little concerned about the RA of the block though. Its rough enough from whatever resurfacing technique they used that I can feel my fingernail "zip" across the surface. Anyone care to comment?