I looked at my engine today after ghettign the head off and I have 3 melted pistons. I have no fucking idea why. My egt's were fine it was datalogged and everything. Looks like I am going to get soem new JE's in there and sell the damn car!!!!

Why you selling the car?

3 JE's simply do not melt.

EGT's are not everything and datalogging is not enough. You needed a wideband.

Well they did. 1,2 are the worse. The part near the indention is melted and i can see the ring on numer one because the metal is pulled back some.

Damn!

take some pics!

I would have to say the same as Chris, three pistons dont all melt w/o you having MAJOR problems before they all went.

I dont have a digital camera. But i will try to get some nromal pics and maybe scan them.

I am going to give sme info on this to see what you guys think.. They day I thought my headgasket blew I overheated pretty bad. My water temp jumped up very quickly and the waater was boiling. It was like the temp gauge was a rpm gauge. Thats how fast it moved. Maybe when i was under boost at 15 psi and the temp gauge shot up it got so hot that it melted stuff. I know its crazy that i can melt 3 JE's but I did. I might get some new JE's and maybe run lower boost and then decide what I want to do with the car. We will see. I dont think I will be happy with any other car though. I love mine but it has just been giving me tons of problems.

Also...I can wiggle the pistons number 1,4 a little in the cylinder. I can actually make a noise when i wiggle them side to side. Is this because those pistons are melted a little or because thats the way it is supposed to be?

ouch

Well I think i am going to rebuild again!!! I dont think I can sell it. Looks like its going to be on engine number 3!!! Hoipefully this one will last more than 2000 miles.

if you can wiggle it it sounds like your skirt collapsed too! That is simply amazing, did you not hear the prdetonation?



Lane Adams

stock 95rs=backroad rally champion

Yah i heard sme weird noises once in a while but I didnt sweat it. Boy was I dumb. I know what to listen for now though.

don't worry my friend made a similar mistake with his mustang, he thought the predetonation was his exhaust making a funny noise :( . Now it has like 0 power.


Lane Adams

stock 95rs=backroad rally champion

there should be a little play in the pistons because they have to have enough room in the cylinder to expand because metal expands when it gets hot.

Damn, sorry to hear that Dave!!

So, what exactly SHOULD we be listening for?? Right now my car has lots of piston slap when it's cold, and the engine has to be warmed up fully before it goes away. And I have a noise that sounds like a small exhaust leak. Any suggestions??

The pistons shoulnt have enough play to make any noise when wiggling them. It had to be hot as hell to melt those pistons... a new engine might be a good idea... I would imagine there being more problems there from the heat then just your pistons...Mabey some warping and stuff...who knows. Good luck.

>Damn, sorry to hear that Dave!!
>
>So, what exactly SHOULD we be listening for?? Right now my
>car has lots of piston slap when it's cold, and the engine
>has to be warmed up fully before it goes away. And I have a
>noise that sounds like a small exhaust leak. Any
>suggestions??

Your engine is fucked, too. Guys, piston slap is a very much bad thing. You should not be able to take you hand and pop the piston back and forth in the cylinder, the expansion you are talking about is minimal and you cannot move the piston back and forth. BoostedGS, pop pcv valve off of the valve cover and start your car, if what you say is true enjoy your engine's impression of old faithful.




Lane Adams

stock 95rs=backroad rally champion

Pics will be up tomorrow.

well i hear my forged pistons slap some and i know that is why you never find forged pistons in a factory built engine they are just too noisy,,,,,

Dave,i guess this would be a good time to move on to a 2.4 swap...

sorry to hear that bro.

Shit Dave...sorry

Damn Dave that really sucks. I hope nothing happens to my car...
Remember when I was asking about too much timing advance at 15 psi and the SAFC....I bet that had something to do with it...
You needed a MSD to retard your timing. I have learned about it from people who are making a lot of power and they all have told me the same thing "DON'T RUN 15 PSI WITHOUT MSD OR CRANE TO RETARD THE TIMING"
You can get up to like 25 degrees of advancement at 15psi.
Plus you should have tuned it on a dyno.

That is why I am seriously thinking about going with 315cc injectors, SFMU and no SAFC, until I buy the MSD.

Oh yeah I also have loud piston slap in the mornings, I have almost 0 blow bye, and my compression the other day was 200, 195, 195, 195.
Piston slap is normal.

lots of cars came from the factory with forged pistons, one example is the 5.0 mustang ( fox-body, or 94-95). You guys with piston slap, when you put your new pistons in, did you bore, mic, and hone the block?



Lane Adams

stock 95rs=backroad rally champion

I'll bet most of us did ^^^^. JE pistons make noise. Period. Now, you shouldn't be able to move them enough to hear noise, but cold start up piston slap is perfectly normal with JE's.

Dave, what did the spark plugs look like when you took them out? I agree with Chris, you have to have had something seriously wrong to melt pistons. When you rebuild, I would spring for a new EGT gauge if I were you.

Detonation. Do you remember an old car that your parents may have had that when they got on it hard (going up a hill for example) the engine 'rattled'(knock and ping)? That's detonation. Sounds like someone dumped a few ball bearings in the engine, but as soon as you let off the gas it goes away.

Good luck Dave, I know this is dis-heartening, but hey - those pistons will make really cool paper weights....


Oh yeah, definately retard timing over 10 psi. If you don't have an ignition now, get one before you roast more pistons.

It sucks to hear that this is happening to you again. I hope things will work out for you. As for the engine, I don't want to jump to conclusion, but I firmly believe that it was detonation from not having any timing retard when you run over 10 psi. Like the others have mentioned, somehow tuning with just the egt and air/fuel gauge isn't enough. Even when datalogging, some softwares don't even detect knock counts in our engines.

Can someone explain how detonation melts pistons? You have to get some very very hot temps in order to melt pistons. I never thought that detonation can cause that much heat to build up? Now cracking rings or ring lands, or cracking pistons is what i always thought detonation could do to a motor. Basically, you can get detonation two ways. 1- you run too lean 2- too much spark advance. Now if you get detonation by too much spark advance, i'd be willing to bet there will not be enought heat to melt a piston, just crack a ring or a piston. Now, if you get detonation by running to lean, you have MASSIVE temps with that situation...i'd bet thats what did it..

That's what I was thinking too... Remember... forged pistons melt at the same temps as cast ones. Running lean will kill them just as easily as it will a stock piston.

Yeah, thats what my understanding was as well. Detonation will knock the shit out your pistons and crack em all up. I gotta agree with XtremeRS on this one - it sounds like you got WAY too lean.


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Well i have the 440's and the afc and it was tuned for .94. I was getting almost 100 psi of fuel. There is no way I was running lean!! I was heatring detonation but i didnt wantr to believe it becasuse when i datalogged it it only got 19.5 degrees of timing. But i guess it was detonating pretty bad. My psitons arent totaly melted just the side of 2 of them is bad. I will post the pics tomorrow for you guys to see them. I am ordering the 8:8 compresssion pistons and JE rings from HRC monday. ALong with a new set of bearings. I am going to get the thing running again and we will see if I keep it or I just may sell it and get a 1g AWD and a back up car too.

hey dude, good luck.. what kind of bearing are u going with now?.. hmm isn't 100 psi of fuel for using 440cc injec very high?.. u also still got the hrc fpr right? i know it may treat u well now, but if u really want to be safe get a better fmu like the super fmu.. do u have a fp gauge while u drive ur car to see what fuel pressure its giving u ?...
just a thought dude...

Michael 99gs
HRC Stage 2
Stage 3 process begins anyone got a 420a block thats not spun etc?

http://www.dreamwater.net/purplebeast

A buddy of mine with a 1G AWD melted (put a hole) in the top edge of his stock pistons from running lean (~19 psi) on stock internals. The 4G63 internals are pretty stout. Running lean melted his pistons when he was racing another car on the freeway. I know it's probably not exactly the same cause as in Dave's situation, but detonation is detonation.

The EGT temp gauge is quite accurate, but sometimes they don't respond very fast. You could have a lot of "knock" counts before you reach the top of a long pull, before realizing the egt temp is climbing. Melting forged pistons probably did not happen instantly in one or two runs. The damage probably accumulated over a period of time, before the final "bang" actually took place. Just my thought.

I wouldn't even think about rebuilding until you find out that caused the melted pistons.

There was definitely an issue with your fuel. At 19.5 timing advance and .94 a/f, I very much doubt the pistons would just melt. I'm guessing that there were some more subtle, yet very apparent explanations for the melting.

Again, keep investigating!

Where was your EGT probe mounted?

Well I could here a ratling noise every once in a while. I wasnt sure if it was detoination but now I know it was. It almost sounds like a can of coke that you put BB's in and shake it up. Like a rattling sound. I wish I knew more about how our cars timing is supposed to react to boost. I datalogged the car but I am not sure what to look for throughout the rpm range as far as timing is concerned. I am going to post the datalogged runs so maybe someone can tell me what was happening.

yeah, detonation sounds like a diesel engine, because its doing the same thing a diesel engine does


Lane Adams

stock 95rs=backroad rally champion