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-   -   Thirsty Piston (https://www.miataturbo.net/general-miata-chat-9/thirsty-piston-52188/)

chicksdigmiatas 10-01-2010 07:53 PM

My machine shop back home would have taken care of that. I don't know who i will trust around here. A couple of locals have given me names. I hate that for you. I am in for pics of bottom too.

yellowihss 10-01-2010 08:07 PM

I would buy a 99 head and all the aftermarket bits and see If they will do the work for free instead of rebuilding that one. This is assuming they are taking responseabilty for it.

Faeflora 10-01-2010 10:19 PM

Wow. If a rod actually broke that will be the first M-tuned H beam style rod I will have heard of breaking. Sorry for your loss.

magnamx-5 10-02-2010 04:17 AM

i bet the piston wall clearance was sloppy and that bent a rod wich eventualy broke still im sorry to see another perfectly good motor go to waste. I hope the shop does right by you.

baron340 10-02-2010 09:55 AM

I don't know about the piston wall clearance honestly. I never had any piston slap, so I doubt that was the issue. Maybe, but I doubt it. There is another guy locally who has the exact same setup with the machine work done by the same shop. He had someone else assemble it though. He's never had any issues with piston slap or anything either. At this point I don't know what I'm going to do. We'll see what they say, but worst case scenario I found a decent 60k 94 motor that I'll drop in.

baron340 10-02-2010 06:38 PM

5 Attachment(s)
Well.. I pulled the block out today. As I was unbolting the clutch, the motor suddenly decided it would turn again. In it's sudden turn, the thirsty piston popped out of the block to the point where the first ring was above the deck, allowing me to pull the piston out. Here's what I found.

Attachment 193885
Attachment 193886

Not pretty at all. So I get to looking closer. There is one circlip in place, but the other is no where to be found. Not surprising given the damage. I hope I never find it down in the block, meaning it was never there. But I did find some more interesting clues.

Attachment 193887

Those grooves are parallel and exactly the same width as the wrist pin, even though wrist pin is now centered, it had to have come loose at some point. These wrist pins are floating right?

Attachment 193888

Then some more grooves, I'm assuming the one that ultimately resulted in the hole in the sleeve.

Attachment 193889

I also found this... I dont' know what it is or if it's supposed to be there. The little wire looking thingy above the crank. They aren't present in the honda blocks I've rebuilt, and I never saw the inside of this one.

Stealth97 10-02-2010 06:49 PM

That wire looking thing is the oil squirter. It looks to me like the piston just decided to come apart for no reason, or a wrist pin clip got left out, and it walked. I'd bet on the latter... yes the pins are floating.

yellowihss 10-02-2010 08:07 PM


Originally Posted by Stealth97 (Post 637865)
or a wrist pin clip got left out, and it walked. I'd bet on the latter... yes the pins are floating.

I think we have a winner.

yellowihss 10-02-2010 08:12 PM

Looks like the rods are good.

Faeflora 10-02-2010 08:51 PM

Soooo, how did those detonation pits happen in your head? Was it like that when you put it on?

baron340 10-02-2010 09:23 PM

I'm hoping the pin walked as well. I honestly have no clue if the head was perfect when I put it back on there. There weren't any glaring signs but I also didn't inspect it with a magnifying glass or anything. Upon closer inspection though, it's not quite as bad looking as the pictures portray. It was dirty in the pics and some of that is from droplets of coolant and oil. There aren't any pits on any of the other cylinders and none on any of the pistons. So if there was some detonation I'm guessing it happened in the last moments of it's life.

magnamx-5 10-02-2010 09:59 PM

looks like they only did one circlip or the shit wasn't seated correctly on install.

M-Tuned 10-03-2010 09:17 AM


Originally Posted by faeflora (Post 637661)
Wow. If a rod actually broke that will be the first M-tuned H beam style rod I will have heard of breaking. Sorry for your loss.

Still batting 100% for our Rods.. New batch arrives this week..

Sorry about your loss.. My guess is a weak damaged piston or the clip was missing / loose on the wrist pin.

baron340 10-03-2010 10:02 AM


Originally Posted by Marc@M-Tuned.com (Post 637976)
Still batting 100% for our Rods.. New batch arrives this week..

Sorry about your loss.. My guess is a weak damaged piston or the clip was missing / loose on the wrist pin.

Nope.. you're rods are still 100%. Even the one that ran into the block and managed to carve a couple notches out of the iron aren't even scathed. I'll have some more pictures of it when we tear the bottom end off and I can get to the bottom of the cylinders but it really is quite amazing. Taking it back to the machine shop on Thursday when I'm out of class for fall break.

magnamx-5 10-03-2010 10:37 AM

still i would get the rods that hit the block checked for cracking it is amazing they held up to block contact like that. i hope the shop does you right.

Faeflora 10-03-2010 12:52 PM

Regarding H beam rod failiure:

FWIW I googled around for a while and found this really good tech-heavy thread:

http://speedtalk.com/forum/viewtopic...56d1ce84caea98

With this pic: http://i344.photobucket.com/albums/p...2/DSC00996.jpg

H beam rods do indeed apparently fail. From the thread, not from the HP that our motors see though. Also, FWIW I am running M-Tuned rods as well. That came out of a motor that had heavy detonation, nothing piston shattering, but melted shit pistons. The rods were just fine.

baron340 10-03-2010 01:39 PM

Oh don't worry, that one rod will be tested thoroughly before going back into a motor. If I have to take it down to the materials sciences lab and bribe a professor or two, I will. But in the end, it all depends what the shop is going to do. A very likely outcome is them saying there is nothing they will do and I drop a stock motor in the car. And ultimately, this could've happened from manufacturing defects, although unlikely. On top of that, a lawyer and court costs would be more expensive than just replacing the broken parts myself.

Ninja edit: That thread on speedtalk is pretty awesome. I don't think I've ever seen so many really smart people argue about car stuff before.

baron340 10-07-2010 01:33 PM

Well... the machinist basically said "you're screwed"... he swears that this failure was caused by manufacturing defects. Claims he's seen it dozens of times in Mahle manufactured pistons. Apparently they put out batches that were improperly heat treated, making the ductility of the 4032 alloy even lower and they crack or outright fail almost immediately. So my new question... has anyone else seen/heard of/experienced any similar failures with supertech stuff? If that was the case, an entire batch should be bad.

Oh yeah.. and does anyone know who exactly makes Supertech's pistons?

gospeed81 10-07-2010 01:41 PM

Passing the buck...awesome.

I don't see how even a poorly made forged piston would fail without having seen any boost or det.

chicksdigmiatas 10-07-2010 01:59 PM

Call the manufacturer and see. I would try to get someone to do it. See if you can find that clip. Did they offer to dissassemble?


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