Hey everyone, I have 122,000 miles on my ls1 and it has started to make a knocking noise after it sits for a while when I start it up. It will do it for about 5 minutes or until it warms up. It gets faster with acceleration. But it only does it when it is cold. Does anybody know what it is and if it can be fixed, or if it will become a major problem?? Any help is greatly appreciated. Thanks!!!!!

 

What is your oil pressure on startup and warm?

edit :

It looks like you have not touched anything internal, I had the spring in my oil pump give out and had similar conditions before it spun a rod bearing.

If your pressure is low then you need to not drive your car, and consider ordering a new oil pump, oring, and while your in there you can eaisly do a cam swap if you have the cash.

 

My engine does the same thing... I've been told it's piston slap?! and normal?! my car has 101k on it.

 

Yeah, IIRC some years had no coating on the sides of the pistons and they had to get to operating temp before the clearances were correct, I don't recall which years, but it seems like it was 98 and 99.

I don't know if its enough to be a "knocking" noise though.

 

usually piston slap only lasts one to two min, CK oil press

 

Oil pressure when I start it up is about 40-45, then when it gets warm it is around 25-30. I am running Mobil 1 10-30, and I live in florida. The oil temp very rarely ever gets above 140-150. It does last for about 3-5 minutes then goes away. I have no idea what I should do??!!??

 

Generally you need 10 psi per 1000 rpms, and if you are a stock eliminator racer, a little less. I think you are hearing piston slap. If it was a bearing, the engine would die soon (probably already). Nothing to do but drive it. If in a couple thousand miles and not problem, gotta be piston slap.