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-   -   bottom line on piston slap (https://www.scoobynet.com/general-technical-10/218581-bottom-line-on-piston-slap.html)

dr jim 10 June 2003 06:49 PM

can anyone tell me what the bottom line on piston slap is. my 97 uk car which has 35000 miles on has just been diagnosed as having it when cold. dealer quoted 1500 to fix with new no4 piston but also said it is common and does not need doing (so why quote 1500) has anyone got any advice if it should be done or leave alone

dr jim 10 June 2003 07:57 PM

anyone???

THOMO 10 June 2003 08:38 PM

DONT WORRY ABOUT IT MY MATE HAS ONE HE DID 160 MPH AT THE WEEKEND
PUT SOME SLICK 50 IN THE ENGINE AND KEEP IT AS COOL AS YOU CAN WATER WETTER ,OIL COOLER ETC. AND DONT DO 160 MPH !

dr jim 10 June 2003 09:07 PM

so are u saying slick 50 will get rid of the noise on cold start?

THOMO 10 June 2003 09:25 PM

no it will coat your internals to run smoother lasts 50k.

dr jim 10 June 2003 10:19 PM

so does anyone no the bottom line

1. is piston slap ok
2. is piston slap bad
or is it normal for these cars

Shropshire-Guy 11 June 2003 07:41 AM


Ive got it mate too. Was quoted £74 for Piston. £200 for Gasket set. £835 Labour. Got mate whos a mechanic plus a certain Gentleman who is on scoobynet from Wales And im goona do it myself within next 2 weeks. Have built Engines before so cannot see a problem so will let you know

Midget 11 June 2003 11:07 AM

Piston slap is caused by the piston skirt tipping the cylinder
bore on its thrust side as the piston travels down on its power stroke.It is generally accepted that it does not affect performance .Having stripped a few I noticed that the cylinder bores are generally unaffected and once the rings seal well and do their job you should have no probs .
Piston slap only causes a problem if it gets so bad that the knock sensor interpets the noise as detonation / pinking and retards the timing but as the knock sensor only comes into to play when the vehicle is running at operating temp it would want to be really bad.The output reading from the knock sensor can be read when the car is hot by a dealer with the scan tool for subaru you dont want to see anything in excess of 10 degrees retard .





NENO 11 June 2003 04:36 PM

Fifteen hundred quid! Are they having a laugh :confused:

Opinions differ greatly, but it seems to boil down to this. If it's bad fix it, if not leave it. What constitutes bad is a matter of opinion.

Mine was so bad that I was embarrassed to start it from cold in a crowded place - it sounded like a diesel ;) Scoobysport replaced the piston for £600 all in and it's run like a dream ever since.

Hope this helps, there is a lot of info on search

THOMO 11 June 2003 08:44 PM

i agree £1500 i can get an engine for that.have a look around s guy.and i can get 4 forged pistons rods and bits fitted for that price .email me for details


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