Piston slap, maybe not!!!

[vettenuts]

Terry Dyson, an oil analyst, is trying to figure out what is causing our engine noises upon cold start. Very interesting reading at the link below. One theory being investigated is oil pump cavitation on cold start, very interesting theory to say the least since my car makes noise, but I never thought it sounded like a piston slap noise. Hope everyone can benefit from this link and in the end I hope we find the problem.

Enjoy

Link to Terry's thread on Bobistheoilguy

 

[Hib Halverson]

I just spent a little time on the thread at that link.

I think the thread is very general, covering everything from the 6.6 Duramax diesel to in-line engines.

With respect to the LS1 and LS6, it's been pretty well documented that a clicking/light knocking/rattling upon cold starts that goes away after a start as the engine warms is cold piston knock and not oil cavitation in the oil pump.

 

[theplayer]

What is "dino" oil? They tell us to put Mobile 1 synthetic 5W30 in it. The fix did include the tapered ring.
Vettenuts: sounds like you have the exact same problem I had. I assume you read my post and know that they replaced my pistons. It is quieter now but not gone. I am going to drive it for awhile and just see if it gets worse.

 

[vettenuts]

I just spent a little time on the thread at that link.

I think the thread is very general, covering everything from the 6.6 Duramax diesel to in-line engines.

With respect to the LS1 and LS6, it's been pretty well documented that a clicking/light knocking/rattling upon cold starts that goes away after a start as the engine warms is cold piston knock and not oil cavitation in the oil pump.

Hib, hear what you are saying but my car doesn't really sound like piston knock, but more like a set of old lifters. It goes away after it warms up like piston knock would however.

 

[582Boat]

Engine knock, cold start

Sir: Had a simular problem and isolated it to be loose bolts on the flywheel, tightened them up and it started and ran like a machine should, you might check. doc