hi me and a few of my friends have cossies and all of ours seem to have a funny knocking noise from cold start up and they all clear when there warmed up...even my old saph use to do it. is it common for this? it sounds deep in the engine don't think its followers. all ours have been like this for over a year?

 

More than likely piston slap.

 

whats that mate? is that common? how come it clears up when its warmed up..

 

piston slap where the rings bores where a little common problem on the cozzies especially the earlier engines suffer worst as the gudgeon pin was at the bottom was moved up on later cozzie engines. it stops when its warm as it all expands. My old 3 door sounded like a diesel when started up but went like stink. nothing really to worry about.

 

The wrist/gudgeon pin has never been at the bottom, it was moved slightly sideways, but we are talking a few thou that's all, but enough to stop piston slap, which is not harmful in anyway.
There is more piston to bore clearance when cold as there needs to be, due to different expansion rates of different materials, ie alloy pistons and steel bore, plus all pistons wrists are offset due to having a thrust face, so nothing to worry about.
It's quite true earlier pistons had more pin offset.
tabetha

 

i tought this was only in the very early cossies ,as ive had a few and have never had it .

cheers james

 

Yes mine sounds like a diesel until warmed up then all is quiet, nothing to worry about at all as said.

 

i thought it was the 4x4 onwards that got the offset gudgeon pins?

none of my 4x4 saphs had piston slap but my 3-door has due to speccing 2wd pistons from cosworth racing

 

correct !!! also race pistons have a central pin design for high rpm

it was stated in the 3dr and saff 2wd handbooks that this is common and will go once up to temp

but people never read them and ford had many worried customers hence why they changed the design on the 4x4

Paul

 

well ive had two 4x4 cossies with piston slap when cold.

Bore wear contributes to it im sure...

 

without a doubt

 

thanks for the input... perhaps it might last lol...