Engine knock when cold?
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 326
From: CA.
St. Jude Donor '13-'14-'15
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
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
Instructor
Joined: Nov 2010
Posts: 145
Likes: 0
From: Des Moines Iowa
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.
+1 on letting them warm up.
My dad still has the 2000 camaro and it has over 100k now and runs great.
Safety Car
Joined: Oct 2000
Posts: 4,949
Likes: 10
From: Monticello MN
Race Director
Joined: Dec 2004
Posts: 13,760
Likes: 75
From: Haymarket VA
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.
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Le Mans Master
Joined: Jan 2009
Posts: 6,226
Likes: 33
From: Morton illinois
St. Jude Donor '14-'15
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
Instructor
Joined: Nov 2010
Posts: 168
Likes: 0
From: Northridge CA
What is "Seafoam" treatment
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.
