Not that long ago started the car in the morning and went to pick up the lass (As you do!!) and happened to notice the car was ticking over alittle more lumpy than normal. Thought nothing of it just carried on like normal. Up to this point I hadent toasted the car yet. Again picked the lass up took her out with her mates. Dropped them off thought her we go lets get some decent speed going! so put the old lead boots on and put my foot to the floor. The results was lower than normal boost (1bar instead of 1.3-1.4bar) and not that responsive. Lone behold i was nearly out of fuel and it started to stutter.

Stuttered to town and filled up. Whilst there reset the ecu thinking it was a recuring ecu fault. Set off home put my foot down and no boost!!!!!!! and a faint cloud off smoke appeard. Got home checked the dip stick, and found a smidgen of oil just touching the bottom of the stick!!!!!

Couldnt afford to get the job looked at so stripped the engine out and stripped it down my self. I found that i had melted a piston and had welded a peice of piston to the bore!!

After my long story!!
WHY DID THIS HAPPEN???????

Information needed to answer the above question!
Subaru Impreza WRX (import) 1994
full stainless 3" exhaust with twindump de-cat magnex downpipe.
K+N 571 induction kit,
Mines Ecu
The only things i put on the car was the decat downpipe and air filter. I ran the car always on shell optimax (no ocatane booster)

Any one else suffered????
Any advice on preventing this from happening again??
Any general info most appreciated!!
Regards Ronniebiggs

 

How long before this happened had you checked the oil level?
I only ask as obviously low oil level would cause it......

Col

 

Turbo is dead right,and how many miles had the engine done since the last oil change? If you run a high performance car you have to be prepared to do a bit towards taking care of it. They just dont last for ever with that kind of treatment.

Les

 

Sorry, but the following mathematical formula applies:

Rocker cover leak X High oil pressure = Lack of oil distribution = meltdown = big bill.

I had the same on a GT4.

Tough luck geeza

 

leaking rocker cover will not lead to oil starvation by itself.

sounds like the lack of proper 100 octance has taken its toll

 

Im with Paul on this.... running a jap tuned ecu (or was it set up in the uk?) at 1.3 bar it was only a matter of time before the pistons decided enough was enough. Do you have a knocklink? And not adding octane booster would have put the nail in the coffin. The prodrive ecu running optimax is not far from detting and that runs less than 1 bar!!!!!

Tony.

 

a leaky rocker cover will lead to oil starvation if all the oil leaks out and there's none left.

 

What are the other bores like, with insufficient oil you'd expect them to be badly scuffed as well. If they're all damaged just sounds like an oil leak, if not then maybe the oil use was just an after-effect of something else:

On the knackered cylinder, where's the majority of the damage? Is is on the exhaust valve side? Does it look as though the piston has melted from the top or just the side? If it's the top near the exhaust valves, check the injector flow on that cylinder, could have been running a bit lean. J

 

Or low oil as a result of excessive blow-by caused by high-boost. J

 

I meant that just having a leaking rocker cover will not cause a drop in oil pressure. Obviously if ALL the oil leaks out you're screwed, but the oil pressure isn't a function of crank case pressure.

if you hole a piston (from det etc) the oil will dissapear rapido, I suspect the hole in the piston might have happened first, although it could have been hanging on (oil squirters on older cars) until the oil ran low and the piston cooling was reduced.

But as people have said, you have to look after the car, it's not rocket science.

Paul

 

Check your oil level every week, you most likely could have prevented this failure.

If you do that, you will start to undertand how much oil the engine burns, even if that is none.

Some day you may sudenly discover your oil level is down lower than normal. *big flashing neon sign* something has changed, check it out!

A posibility is that the turbo has started to fail, once that happens the engine wont boost as much as before, it will also start to eat oil as the turbo bearing starts to collapse and oil gets injested. High oil consumption has the effect of lowering the octane rating of your fuel, leading to det, leading to melted pistons. Lots of failures are inter related.

people in this day and age are lazy, they expact everything to be done for them and they expect cars to last for long periods of time between services/checks. That mentality is stupid and will only lead to preventable expensive bills. Take some responsibility for maintaining your car, do regular checks, if you dont you are increasing the risks of a failure.

Good luck with the repair, get the turbo checked!

 

.... also got a '94 WRX and general advice has been not to re-set it (link ecu) above 1.1 bar, otherwise expect trouble.

not much help, but as standard boost for the car is .7 bar, doubling the boost may be pushing the limit?

regards

 

Sorry for taking so long to reply. Internet was playing up!

The car did come with the ecu in from japan, so therefore was set up over there. The mark on the bore was at the top towards the head of the bore. It hasnt scraped the bore it has welded a peice onto the surface of the bore. Im going to try and use some emry paper to flat it off and i hop that will save the bore. The part of the piston that went was a little peice at the top just on the curve. It hadnt gone all the way through. Instead it had smashed the 2 rings and the oil seal as was loosing compression through this way.

Anyone got any advice on the bore. On possibly how to get the mark out?? etc most appreciated. My worst fear is that the block is knackered and i have to get a new one as that is a total rebuild and im not a mechanic.

Many thanks for the replys.
Ronnie

I have no knock link etc. Was going to ghet one but times where hard so i put it off!!

Havent had chance to check the injector for obvious reasons. May have been running lean but wont know untill its back together.

C

 

I dontmean to offend or be funny

BUT

If you cant be bothered to take 30seconds out of your busy life every morning before you start your car to open the door pull the bonet release (7 secs) walk to the front of your car lift the bonnet (10 secs) Pull out the dipstick ( 5 secs ) look at it (3 secs) put it back and close the bonnet (5 secs ) then you have NO ONE ELSE TO BLAME BUT [b]YOU

 

>> Nearly a year of on and off using went by before it happened. Never checked the oil level and I must make a conffesion <<

Hoisted by your own wossname ... even so, bad luck and well done to have the b***s enough to own up.

Many drivers today, lulled into a false sense of security by ever wider service intervals for most ordinary cars (designed mainly to attract high mileage fleet buyers where service intervals still come round frequently) don't bother to do those essential routine checks. ALL fluid levels, tyre condition and pressures etc. need to be checked. Sure, you'll maybe get away with it by pure luck for years but one day ....

I was on a training course not so long ago where the woman next to me had two high level acadmic degrees. On the way in one day her Renault engine seized up irrepairably solid. Asked if she checked her fluid levels frequently (Oh matron .. ... she had to admit that she did not even know where her bonnet release was. And anyway, only British cars are unreliable apparently. So, there's a lot of it about. There's a world of difference between education, academic qualifications and intelligence .....

Lack of or low lubricant levels will stress all parts of the engine in many ways. With the resulting huge heat build up in hot spots and from your description, looks like a ring or two snapped through lack of lubricant and the small piece became wedged between piston and bore .... nasty...

You maybe lucky and get away with it with your plan to clean up affected areas .... let us know how things shape up with the final outcome .....

Fluid level checks, NOT just the oil, but coolant, brake and PAS reservoirs need to be checked. Sudden changes from correct levels is an indicator that something is wrong and needs investigation.

Moral ... check those levels .... they can be the harbingers of bad news well before it arrives ..... CHECK 'EM! Then you'll have time to rectify before it becomes too late.

 

As a couple of people said, low oil will not cause a piston to melt.
Weak mixtures, whatever the cause, will.
If it has melted that badly, then there must be some issues with the fuel system, either that or simply running far too much boost ( and probably running weak, and or detonating )

 

you mentioned dodgy tick over, doesnt a faulty MAF make it run lean? and lean running and high boost leads to melted pistons

 

bigmac...... has a point, though you'd expect all cylinders to run lean if that was the MAF was faulty, so you'd expect to see some damage on their piston crowns (a pitted surface, normally on the exhaust side, is a good indicator of knock occurance).J

 

One thing sticks out in my mind - early car - small injectors, 380s? from memory - running 1.4 bar - standard fuel pump - could very likely be running very lean due to not enough fuel getting into the engine.

My car at 1.3bar, with 440s and then 740s ran lean until I uprated the fuel pump.

Rannoch

 

Like i said before there was a mark at the top of the bore towards the valves on the bore. I think its the piston not the ring that has welded to the bore. If it was the ring it would have scored the bore. The bore is fine apart from the addition of about 2-3 mm off piston on the surface. I dont know have far the car has been moded. Becasue it hhad the mines ecu and a panal filter and when you look at the mines site www.mines-wave.com you can see there are other things that could be on. Like injectors etc. I wouldnt know how to check the injectors. But if anyone knows how to. I will check and tell everyone what they are. Equally where is the fuel pump found on my car.
Regards Ronnie

 

THe problem with det related damage, is the det can happen over a long period of time weakening the piston with high temps and shock loads. Then one day the pistons just gives up, los seem to go on overrun just as the throttle is lifted. THe shock loads can do a bearing shell too, slowy over time till NIP.

Don't feel bad, it's a common problem. I don't think it's a mistake, just people aren't as aware as they could be about the problems with high boost, small injectors and Jap ECUs.

How bad is the mark on the block? If it's less than 0.25mm deep, the block can be rebored, but that means new pistons. Yo umay do better to sell the short engine to someone that wants to build a closed deck block motor. Then buy either a short engine to replace your broken one.

Alternative, the mark on the block might be some aluminium from the pistons welded on the bore. If so you can usually scrape it off CAREFULLY, followed by fine wet-or-dry. Not as good as a pukka hone but you get quite good results nonetheless.

If you get the bores sorted out (without a rebore that is), then a set of second hand pistons for under £200 could sort you out. Add about £250 for gaskets, cambelt and service items and you could be sorted.

Paul

 

Cheers Pavlo. The mark on the bore is raised on the surface and not into the bore. I was going to wet and dry it out!! hope that works. Also Im not going to change all the pistons. Im getting just the one that has broke. I can get a second hand piston and rings for £35. I know they are worn etc but its a damn site cheeper than replacing all 4 off them and the rings. I hope the mark comes off but i havent tryed yet!! so dont know.
Regards Ronnie

 

Nearly a year of on and off using went by before it happened. Never checked the oil level and I must make a conffesion
I did have a leeking rocker cover gasket. However it never leeked that much (unless it got worse. Which I could actually smell oil a bit worse than normal a couple off days prior to it happenening) and I did check oil level occasionally and it never got low. It dipped off full to 3 quarter then half but no lower.

Regards Ronnie

[Edited by ronniebiggs - 3/6/2003 11:53:02 PM]

 

detonation due to low fuel pressure as the pump sucked in air? Or lack of lubricating oil?

Either could have been prevented.

[Edited by Turbo_Six - 3/7/2003 12:27:22 AM]

 

If you run low , or out of oil the first thing to go pop is the crank , it will knock , if you melt a piston its down to fuelling , in theory , if you were on full boost and it ran out of fuel then that few seconds is enough to damage a piston , I know , been there dun that with the rally car ...

[Edited by Ian Godney - 3/7/2003 4:13:26 PM]

 

Firstly gossythevaleter
Im not a fu*k whit!!!!!!I did check the oil on a weekly/two weekly basis. I cant believe you proverbly timed yourself to get them figures that you quote. The time it takes is irrelivent. Its obviously a short time.


Your reply was pointless!!! and I have just done the worthy think of your thread and printed it out and wiped ,my a*s with it on the toilet.

To everyone else I must appologise for my lack off respect for the above named member in my thread!! but he obviously just wanted to notch another thread onto his tally and waste our time.

I dont think it was oil. I must stress that. The oil level was a product off the smashed ring. The turbo seems fine and I believe. I melted a piston on lack off fuel. But the only thing that confuses me is the fack that it was like that in the morning and did id from start up. I may havbe turned the engine off to soon after a speeding session the night before or something like that. Again not sure because it was quite a while ago now.
Many thanks for all sensible replys
Ronniebiggs

[Edited by ronniebiggs - 3/8/2003 6:59:59 PM]