Blown head gasket. Removed head today.
 

Head gasket has slightly over 1000 miles on it however it is a gasket out of an ebay gasket set.

Head bolts have over 195k on them.

Those are the only reasons I think of. Im 99% sure there wasn't ever any detanation. The car wasn't over heating. Cylinder #2 is the only one I can see water in, the others look dry. Here's a pic of the plugs.

1,2,3,4
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double check the torque on the head bolts. my brand new gasket blew within 25 miles. my torque wrench was waaay off calirbration, like 20 lbs less. put my bolts at 40 lbs.

http://boostedmiata.com/blown_engine/headgasket.jpg

Who built the motor? whatmiata?

Did you put a straightedge on that head and made sure it was in specs?

Yes he did and yes he did.
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99.9% of the time, the reason for a blown head gasket is a warped mating surface...either on the block or head.

He probably fucked something up. My guess. Or you detonated. Pull the head and find out what's wrong. Check the torque on ALL the head bolts before removing it for reference. If it detonated, it will almost always blow between two cylinders. I can not stress this enough, yet you will likely ignore it: DO A LEAKDOWN TEST! There, I said it. Do this and all will be known.

Correct me if im wrong, but I have to replave the gasket in order to do the test, right? Otherwise it will deffinately give false readings, right?
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The test will tell you % cylinder leakdown. If it's blown a head gasket, it will probably leak a lot. :) But doing a leak down test before tearing it down will give you insight as to the actual problem, and what caused it. IE- you may find that pressurizing cylinder 2 results in air pouring out of cylinder three, showing that you blew the HG between two cylinders, hence detonation probably caused the problem. It also might show a trace amount of leakage between 1&2. You may pressurize cylinder 2 and find air leaking into the cooling system as evident by the air bubbles coming out of the radiator. Probably a warped head or deck, improperly torqued head, bad bolts, etc. Or you may pressurize cylinder 2 and find excessive blow by, indicating a cracked ring landing or something of that effect. If it leaks past the rings AND leaked into cylinder 3, you likely had detonation. Where if it only leaked into the crankcase but the HG was fine and no other leaks appear, it's probably from poor machining. (read, honing only instead of bore and hone)

Point is, you'll know exactly what's wrong if you do a leakdown. Don't worry though, like I said, you'll probably ignore this advise and just yank the head off and try to guess what was wrong, fix what you think is wrong, and roll the dice again and see if it fixes it. Check out NA6C-guy, he did this four times in a row. :giggle:

Thanks Pat, The gasket is deffinately shot. #2 cylinder has a puddle of water sitting in it while the other 3 are dry. Also with the car running and the rad cap off the water jumps like crazy.
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wow pats take it easy.... how could you just come on thread and say i "f" up. with out even taking it apart and inspecting your self... you got something against me or something? Ive built plenty of engines and never blew a head gasket. I have a fresh snap-on torque wrench that the engine was assemble with. If the wrench was off i think the engine would have let go and my engine also... phil the thread start/owner brought me the head and said it was fine and did not want me to take it to the machine shop to check it.. so i copper spayed the head gasket put it on and torque down the head to spec, with the original bolts when it said in the factory manual they should be replaced. so who knows the head condition, and what those bolts have been stretch to. also phil did have issue's with water temps (seeing 220+) when he got the engine in. so take it easy with all the putting the blame on the builder.

:fawk:

Yes I did, and whats worse is it was never the damn head gasket in the first place. I was ignoring logic because I thought I knew better (than logic, go figure). The first time it was because of a staple sandwiched between head gasket layers (but the 1.6 isnt MLS is it? So no worries there), but apparently after that, it was my oil control rings, and what I thought was oily coolant, was just oil... stupid me for assuming. I have no advice though, Im probably the last one needing to give advice. Like said, it only took me 4 extra head gaskets, and 4 months of work to get it running (after a full bottom end rebuild of course). :giggle:

You've said some things in the past that showed you weren't much of a machinist/engine builder.

If you didn't check the head, then you don't know if it's warped. No way in hell an engine builder bolts a head down without checking the deck first. It takes a minute of your time and cost nothing. That's ludicrous that you didn't check it. Who checked the deck for flatness? Who checked the head for cracks? Did you chase the threads and degrease the bolts and threads before torquing the head?

If the bolts have been used more than 2 or 3 times before, I would have replaced them. I recently torqued mine for the 3rd time and one reached its yield point stress on the last round of torquing. I stopped before I broke it obviously, but the next time they come out, it's getting new bolts.

Also, did you retorque the head after 500 miles? With a composite gasket you have to, especially for a boosted engine (which should have got a MLS gasket in the first place, hint hint).

So far we have:

• A head that may be warped
• Possibly a cracked head
• A deck that may be wapred
• Head bolts that may be bad
• Head may not have been re-torqued after 500 miles

Sorry, but whatmiata guy ain't building any of my motors. I'd have no confidence in my engine if it lost a head gasket due to one of the above problems. I hope this is the last major issue you have.

CAN I BUILD YOUR NEXT ONE!? :hustler:

lol ok you know what pats......... im sorry you know what your taking about and i dont. maybe you should be a engine builder.. you prob be the best in the world. hey apply for a job in a shop or maybe a high performance shop even. because your the best and right and sorry that i questioned your knowledge.

I've not heard this one...perhaps this is why i'm losing so much oil on my new motor...

Hell, I retorqued my MLS 3 times before I ever started the engine and still had the nuts on the ARP studs tighten up a tiny ammount each time (a few days apart each time). A composite for sure HAS to be retorqued, its not just a good thing to do, its a must.

Very easy to do on a miata, i'm going to check this out tomorrow. I'm sure I need a re-torque. I wonder why FM didn't include this in their instructions they include with the ARP studs...?

When I rebuilt the top end of our integra I also didn't re-torque. It'd be very difficult since you have to remove the cams...

Not related...look elsewhere

I also think you are supposed to do it cold, since the aluminum head would expand when hot. Maybe that is common sense though.

Im not really sure as to why mine didnt hold torque. I may also check mine this weekend. New rebuild at ~350 miles.

I'm not an engine builder. I built a few motors when I was in machine shop back in high school, but none since. (don't have 300k worth of tools at my disposal anymore...) Again, I'm no expert by any means. It takes a lot of know how and real world experience to be a competent engine builder. With race engines and other performance-oriented engines, it takes much more. Details are what separate the good from the best. The things above I mentioned aren't even details.


You shouldn't have to retorque a head gasket 3 times before starting a motor. It's common to retorque a composite gasket though after 500 miles on a cold engine. Also a good idea to retorque any head gasket after overheating an engine, especially 2-strokes.

I think maybe in my case it was the actual studs turning. I installed just as told by ARP and FM, hand tightened into the block till they bottomed out, then torqued the nuts in 3 or 4 steps to 65lb/ft. THe 2 times I re-torqued them, I got maybe a 1/64 of a turn, if not 1/128 of a turn on each of them, so probably not even 1 or 2lb/ft. Just minor slippage, which could have also been a difference in any number of things, temperature, or my wrench. Only felt it as a pop, I guess either the nut slipping and regripping the head, or the studs popping in their bores. Everything was well lubed, so Im not sure how that happened.

Just to say this, don't run the motor. If it gets enough of a puddle in that cylinder and you try to crank it, it will hydrolock and something will give; likely a rod. Check things over very carefully when the head is off to make sure all the pistons are coming up to the same height. If the #2 rod bent any, that pistons won't come up as high as the others. Just put the motor at TDC and check a pair of pistons for height against the deck with a rule (or a dial indicator with a magnetic base, but you probably don't have one), and then TDC for the other pair and compare. They should all be the same of course.

Head gasket is trashed. Everything else LOOKS kosher.
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damn! I do need to run some water through the engine, it cleans it real good!

yeah dude, that thing looks just like mine did. I'm blaming uneven and/or not enough torque to the studs.

Looks :ne: Is. You better figure out what failed, why it failed, and correct the problem or else you'll be doing this again. That gasket didn't fail for nothing.

Yeah I know, thats why I put looks in bold. Once I get it back together I'll do a leakdown test.
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How did it check out before you pulled the head? Or did you not do a leakdown test? ;) I'm laughing.

Is there anything that's not caused by detonation in your book?

Yes. I highly doubt this head gasket blew from detonation. It would have blown between two cylinders if it hat detonated. I guess after he gets the head back on and does a leakdown test he'll know where to start to fix it once he pulls the head again.

No I didn't. The cylinder was filled with water. Even you said do not run the car. The gasket was blown. Doing a leak down test would have shown a massive leak in that cylinder, how would I've known if something else was bag with that huge leak there?



I'm glad your enjoying this.
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You don't have to run the engine to do a leakdown test. Doing a leakdown test would have told you where all it's leaking. It it had any leakage past the rings, or intake valves, or exhaust valves, or a crack in the combustion chamber, the leakdown test would have identified that down to which cylinder. Anyways, care to share what you think the problem is? IE-why the gasket blew?

Well, I rechecked the torque on all the bolts and noticed that several of them weren't at 60ft lbs. Specifically the ones around the #2 cylinder. Now I dont know if it was because I didn't recheck them at 500 miles or if it was put together that way. Im not pointing fingers. I also can't ignore the fact that this was an ebay head gasket and you get what you pay for. I did put 1000 trouble free miles on the car with half of them being at 12.5 psi. I also had temperature issues when I first put the car back together so who knows if that didn't weaken the gasket.
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If it boiled over-overheated, then it could be a HG failure that's coolant temp related. Else, I would say that overheating is not directly related. Several things could cause the bolts to not be tight. Make sure you do everything to ensure you fix the problem there. I HIGHLY suggest you put a MLS head gasket on it. Can not emphasize this enough. It's like 100 bucks from FM. Best $100 you'll ever spend. And get new head bolts for good measure.

;)

Also picked up ARP hardware today.
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That should do it. You going to check, or have the head and block surfaces checked? Dont be like me :giggle:

Your my boy so I wont throw salt in the wound,


:hustler:

^that sums it up tho.


Get er back on the road asap, def at least make sure the surfaces are straight.

Ps--you're supposed to be blowing diffs not HG's ;)

Getting fancy, expensive parts and components isn't going to get you past the basics.

1: Make sure the head and block are nice and flat. Max distortion should not be greater than .0008". Preferably no more than .0002".

2: Run a tap through the threads on the block. Afterward clean the block threads with compressed air. Lubricate the bolt threads with light oil.

3: Clean the head and block mating surfaces spotless. Remove all traces of the old gasket. Use a fast evaporating cleaner (get the highly flammable type) and a lint free rag on the mating surfaces.

4: Tighten the head working in circles from the inside out a bit at a time. Finally torque to final specs. Make sure while final torquing that none of the bolts/studs go limp on you. If they do, you need to replace the culprits.


Get these right and you will not have any blown head gaskets.



Tony

He knows. :cool:

Composite or graphite technologies as less expensive replacements for LMS. DON'T BUY IT. The lateral motion in many engines can destroy the composite core and facing, while the vertical motion overcompresses and "crushes" the gasket, creating leak paths.