kipveteran

My LS1 engine knocks when it is cold but is a little better after it warms up to operating temp. What could make this better?

thealien

Mine does too. From what I have read is many have piston knock/slap at cold start up and the noise goes away after warm.

How long have you had the vette?
Has it always made the noise?
How many miles on it?

Need more info to help.

Z06ufgrad2002

Sounds like normal piston slap. Not much can be done to correct it. But, from what I'm seeing on my own cylinders; it does cause wear over time and now my engine block may need to be replaced due to the damage this "normal" problem has caused over time.

kipveteran

Thanks, I just got my C5 about 2 weeks ago. It has 53000 mile on it. It just bothers me to hear it. I am a very detailed aircraft mechanic.

roadbike56

How many miles are on your engine that it caused this problem to be serious?

Z06ufgrad2002

50,000 miles on the engine. 30K of which I had been running LG G5X3 cam. It also just wiped out the camshaft and lifters so some of the damage could be from the metal floating around in the oiling system. No way to really know exactly what caused the cylinder wall damage but it's serious enough the that the bottom end is scrap. Up to now the heads had never been off the car.

Bent98c5

Piston slap won't wipe out a cam or lifters. You had something else going on. Piston slap is caused bc the pistons expand when they are heated. The engine and pistons were chosen in a way to provide performance. Let the car warm up before you drive it and you won't have any issues. Even if you don't let it warm up it still won't destroy it. It'll just make noise. Just like your valve springs and injectors.

El original

I don't have a knock but after a few minutes running a tick tick that quietens down when hot, any ideas? (don't mean to hijack this thread)

reactor2

Its been several years since I installed my cam (228/232 .571/.573 112) and I HATE it. The valve train sounds like complete $h1t....like a sewing machine about to come apart. Its the worse sound ever. Yes, everything is installed correctly, and the pushrods are the correct length. They are a little louder until they warm up, but the sound never goes away. The engine is quite modified (heads, cam, intake, exhaust, TB, supercharger, etc.) but I'm probably taking the cam out this winter (if I get around to it), I'm sick of the noise....I don't care if I loose a few ponies at this point.

The knock on start up is completely normal (piston slap), my 98 and my bros 04 both do it, and have always done it.

reactor2

Normal

reactor2

If that noise bugs you, put headers and a cam in it and it will drive you INSANE! I absolutely HATE my cam....the valve train sounds like a guy holding a tin tray full of pennies while having a seizure. (I got that from someone else with a cam but it hits home for sure).

DBRASUE

If that's normal what do you call engines that don't have it?

reactor2

Engines that don't have piston slap or valve train noise = not a Chevy or owner hard of hearing.

DBRASUE

I trust this was in jest...
My 2005 Silverado does not have it.
My 2000 FRC HAD it until I replaced the LS1 with a 04 LS6

My hearing by the way is perfect!