Piston problem
Turbo Mini Forums

Some of you may recall last year I put a hole in a piston after running too lean.

About 8 weeks ago I thought I had done the same thing, got the car home on 3 cylinders, took the head off and the top of piston 2 (same as last time) looked knackered on the edge and I resided to the fact the same thing had happened again.

Tonight however I finally got the engine out and started to strip it down, I popped the piston out and was greeted with the images below.

As you can see the gudgeon pin is protruding a lot further than it should be, even out past the walls of the piston a good mm, obviously this has resulted in a rather nice deep gouge in the cylinder wall.

Now the question is, is this my fault (running lean), the engine shop for poorly fitting the pistons & pins, or a strange coincidence. Obviously I would love to be able to turn to the engine shop and lay the blame on them but I need to know if det has caused the pin issue (thats me still thinking its det from the damage to the top edge of the piston), or has the pin issue caused something that has caused the det or caused the damage thats similar to det (in the eyes me an amateur, me)

http://turbominis.co.uk/forums/index.php?p=vt&tid=170151

Whoa fook me!

On 5th Oct, 2014 Shauna said:
What that's crazy, you go commando hahaha! How heavy is your helmet ?

now that's a cool paper weight

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

i'd guess piston before the pin the four verticle marks looks similar to how a 2 stroke piston siezes in the bore, its got bloody hot that...

Speeding is like masturbating, everyone does it, but not all of us film it and put it on the internet

[quote=fab,8th Oct, 2010]fuck off

is it just me or is your rod very discoloured?
good skills on the piston btw

Yes i moved to the darkside

Instagram @jdm_brett

deffo det, lean mixture, timing issues you have dropped in the same trap again! sorry to say,

You MUST!! sort this problem out PRONT! before you go insane with changing pistons not to mention your bank account

what boost was you running, timing and fuel octain and compression ratio?
intercooled or not ?

I, we need to know then advice can be given, to correct the problems.......simple as that simon

Edited by Sprocket on 30th Oct, 2012.

It quite clearly says whoa, not you-lol

On 30th Oct, 2012 Sprocket said:

On 30th Oct, 2012 oli79 said:
Whoa fook me!

Eh, No thanks!



In My Opinion, That little end looks a little blue, maybe suggesting it has been overheated during the piston fitting stage. The piston also shows signs of partial siezure, which could be as a result of the piston overheating as a result of pre ignition/ detonation. The fact that the piston has blown through on the side would suggest a comprimise of ring seal, which, if the pin was gouging the bore before all else, that would explain the ring seal issue. it only got worse from there. I don't see how detonation will cause the little end to loose grip of the pin unless the little end interference was not adequate.

and I doubt you get the machine shop to move on accepting responsability

I forgot to add that I don't think this has anything to do with detonation or pre ignition in the first instance, but more likely as a second since the pin gouging the bore would have been the whole reason for ring seal comprimise, and the hot gasses wooshing past that one area melted overheated the piston. The melted bit just so happens to be directly opposite the area the pin would have gouged at the bore, and the damage just so happens to be pretty much the same width as the pin

On 5th Oct, 2014 Shauna said:
What that's crazy, you go commando hahaha! How heavy is your helmet ?

Benross, it wont be happening again as I'm already breaking and selling the car off. It would have been around 16psi with a big intercooler, I'll have to check back as to what the CR was and I cant confirm the timing as the megajolt and its map have already been sold on.

Sprocket , your obviously diagnosing the issue in my favour in that the problem could have been the fault of the machine shop, but as you say is there actually any chance of me getting anywhere with them and how could I approach it, I'm not angry as these things happen but if its their fault then simply some cost towards new pistons & block would be nice.

http://turbominis.co.uk/forums/index.php?p=vt&tid=170151

Id wana say det there, wether the heat could of allowd the pin to drift over im not sure.

But surely the would of been enough heat there to warrent it?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

On any of the other pistons are there signs of this?

The other pistons all look fine, all 4 rods are discoloured towards the small end so I'm guessing this was from fitting the pins to the rods.

I popped into the engine shop today and they said det and nothing to do with them, saying that the det caused the pin to heat up and come lose and score the bore, not the other way round. They welcomed me to have it independently tested somewhere but said it would come back with the same diagnosis of det.

http://turbominis.co.uk/forums/index.php?p=vt&tid=170151

with the amount of det that it would need to fuck a piston like that I wouldnt be supprised if it rattled the pin out,

I'd say detonation and heat moved the pin. Your fault!!