FirebirdX

So I'm not exactly sure if this is a common problem with the ls1 but when I go to start my 00' T/A when its cold I end up getting this knocking sound but then goes away after about 5 minutes. My dad who used to own an 04' GTO said he had the same problem.
When my car was on the lift getting a new muffler put on, the knocking was coming from near the oil pan and was extremely loud.

Has anyone experienced this, or could tell me if its something I should be concerned about? Thanks.

KevinR

Piston slap. Very common in these cars

Don't stress it

parks450

iTrader: (17)

Yep piston slap. Almost all the ls engines do it. Happens because the skirts of the pistons are so short so they slap the cylinder wall until they heat up and expand.

FirebirdX

Okay thanks for the input, glad its nothing major.

rockinace6

iTrader: (1)

mine did it on my silverado ss with a lot of mods. almost sounds like a bad lifter but when it warms up it goes away. my ws6 does it as well. dont worry. if it continues and increases in noise after a while, it could be a bad lifter if it progresses.