mdixon

When my 2000 Vette is cold like in the morning it knocks a little. What causes this?

tblu92

This is commom in SOME LS engines-- if it sounds like an engine rattle and not a pinging noise---
It's known as a "piston slap"--GM has acknowledged this issue and says there is no fix and it won't affect the engine performance or life--
BUT I always let the eng warm up til it disappears before proceding just to be safe

C.Davis

I had piston slap when cold on a few ls1 f bodys a 98 TA with 80k and a 00 Z28 with 70k, my 00 vette does not have it 70k (yet...)
+1 on letting them warm up.

My dad still has the 2000 camaro and it has over 100k now and runs great.

webelo

my 2000 has piston slap in anything colder than 35 or so. It goes away after about 100 feet.

C5XTASY

+2 on the warmup.
Ed

docohm

My 2001 does the same thing when it's below 40 here, goes away in a couple of blocks as it warms up. She has 80K miles now and still running great.
DocOhm

Marlin

Yea my 01 with about 60k does it and my parents Z28 also has it and they are near/over? 200k on the factory motor.

WKMCD

Most common problem is piston slap as was said. If the car is modded you may have a lean condition as the air gets denser when the temp drops. You could also have carbon buildup on the pistons causing detonation but that is most noticable when hot. Probably still worth doing a Seafoam treatment on it - can't hurt.

VGLNTE1

Im gonn say its not piston slap. its cold as hell out and the oil is thick. takes some time to work it through. Thats just valvetrain noise without oil in it. Mine does the same in this cold. Its fine

rick4grafx

What is "Seafoam" treatment

retired cop

My 2004 does it has 21000 miles. This is my third LS1 they all did it.