have a s2 which had full engine rebuild about 6000 miles ago. recently started smoking etc. and compression was down on 1 cylinder.

Fault found to be cracked piston, it has cracked just below the first compression ring. Why could this be? the pistons are not genuine, they are patten parts - running 16psi. My mate has standard pistons with same setup and he hasnt had any probs. Could it b wrongs plugs or running lean or something?

Nxt question, thinkin of putting some 17" alloys on, has been lowered about 30mm on koni's. Will they catch or will lots of mods on the arch's be required?

 

Can you post up some pictures of the piston?

 

shoddy piston +16 psi + incorect fuelling = det & a knackered piston.
the non forged pistons are only good for 1 bar boost & no piston is going to last is the car is not setup correctly.
ps the wheels will catch, get the grinder out

 

I had the same problem with mine. Done about 400 miles when I found it was on 1 cylinder. Took all the pistons out and found 3 out of 4 were cracked on the ring lands. Have sent mine off to the manufacturer to find out what has gone wrong. Has the piston got any signs of detonation on them?

16 PSi sounds a bit high if its on a standard setup. Low compression pistons might be the way to go.

Cheers
Dave

 

pattern parts?

say no more!

 

My pistons were Mahle though which Ford use as standard.

What make were your pistons as AE pistons which I think are pattern are supposed to be very good.

 

Not sure now, can't quite remember. I know they came from a company called Ferrari's in London, they are a very big company selling lots of engine components. So i wouldn't have thought they were that crap. Just noticed on one of the other pistons as well that the top rings is loose, and you can see what they call 'blowback'?! Will hopefully have some pics later.

Davidnormanuk - Someone on this site is selling some new Mahle pistons, I might get those - any idea why yours cracked? What boost are you running?

 

Have a look inside the piston and see if theres any stamps on it.

Mine have been sent back to Mahle in Germany but havn't got back to me as yet. The only thing thats wrong with my setup at the minute is that the head had been skimmed too much. It was down by 0.5mm compared to a standard head.

I had turned the boost right down to run the engine in properly. Did about 400 miles on it before I did a compression test and found it was down on one of the cylinders. Gutted.