chrispayze

Nice tip, ta.

Sent from an Android device.

robski

Haven't had chance to listen to noise but double check your spark plugs are in one piece and are tight.

Mine made a horrible klonking noise of the earth electrode bouncing up and down..
In cylinder 4 the spark plug earth electrode snapped off causing quite a lot of havoc... costing a small fortune to sort out.

chrispayze

Fairly sure it's coming from further down in the engine than spark plugs, and it's not long since new ones went in, but I'll check em nonetheless, thanks.

BCA

I'm going for cat heat shield, one of the bolts further back on it will have corroded into nothing.

chrispayze

Hmm, doesn't sound like a thin piece of tin, will check it though.

tozerman

Just listened to it at home, piston slap 100% mine is the same, always done it

chrispayze

Thanks Tozerman. Will check the other things for peace of mind, but piston slap seems the most plausible. Clearly it's normal, but how does it not dent/stretch/score the cylinders?!

chrome233

My car is making the exact same noise and a few people on the US Forum are also having the same issue. Have we established that this is piston slap from it being forged? And as Chris said does this not cause damage to the engine?

chrispayze

No more info than in this thread I'm afraid, although I have since had the head off my engine for other reasons and the bores looked in perfect condition. Given the number of people noticing similar behaviour, I think it's fairly normal. It only happens when mine is cold.

I'm guessing that, to enable the high piston speeds, the cylinder/piston tolerance is very precise, but that the pistons are relatively 'loose' to reduce friction and the resulting heat.