davidnormanuk

Just thinking about the Sierra Cosworth 2wd with its piston slap. With the piston moving from side to side in the bore wouldn't this eventually wear the bores uneaven?

Cheers
Dave

Turbosystems

iTrader: (5)

the bores and pistons are already worn uneven hence the slapping
it's an old slapper lol

davidnormanuk

Did they not slap from from new then?

I was reading through the original owners manual and it mentions piston slap in there?

Turbosystems

iTrader: (5)

the first generation engines did but they were made in 1985

davidnormanuk

Hmmm. Thats interesting. I'll have to to see if there's any dates on the book then as mines a G reg.

xr4x4rs

iTrader: (5)

you wil find that its just 2wd engines that have piston slap

wasnt until teh 4wd they got rid of it by changing the piston design for the small end

thats why people use 4wd pistons to stop it

davidnormanuk

I was told that they offset the gudgen pin on the 4wd ones to stop the slap. Will any damage be done in the long term then? I assume people just live with it.

xr4x4rs

iTrader: (5)

davidnormanuk

opps that what i meant gudgen pin

not small end as there the same in all cossie conrods been a long day sorry

well as ive seen 2wd engines with no rebuilds and over 100k i dont see the problem

but with it long term is hard to say

davidnormanuk

Apparently the cars had an engine rebuild 15k ago and new oversized pistons were put in so should be good for a few miles then. I've known bikes last a long long time with piston slap with no problems so I'll see how it goes.

Turbosystems

iTrader: (5)

2wd sapphires had offset gudgeons pin as did the rs500
it was the first generation engines only that didn't, however some of these engines were in the early sapphires

vroooom ptssssh

Doesnt the piston slap just occur on cold startup? after a few mins, pistons heatup-expand and all is well?

abdr500

iTrader: (1)

no it wount damage the engine but the noise will get worse in time and then damage will happen

xr2i-carl

yeah its only very quickly from cold

nellyscossy

the good ole piston slap......my saph does it for a couple of minutes from start up...my 3 door dosent do it at all...but thats had a rebuilt engine from a saph put in it in the past

DENNIS

piston slap is common on all 2WD cossies due to the center gudgeon pins.
most high performance pistons get it as the center pin is better for high revving engines..

no real damage will happen as it only lasts for a little while when cold...

some manufactures still use it, and the noise is classed as " acceptable "

some pistons expand over that of the " norm " so have larger bores and get slap from that .....

as long as it is piston slap due to this and nothing else its fine.....