Knocking in LS1

Reply Subscribe

Thread Tools

Search this Thread

Apr 20, 2009 | 11:45 AM

stumpy9011

Thread Starter

Registered User

Joined: Mar 2009

Posts: 10

Likes: 0

From: Flushing, Michigan

Knocking in LS1

I have a quite a distinct knock when the motor is cold in my 99 z28. Some have told me its normal.. and others say get it checked.
What mit this be.. just a general guess.

Apr 20, 2009 | 11:50 AM

got-a-ls1

TECH Fanatic

iTrader: (12)

Joined: Jun 2007

Posts: 1,438

Likes: 0

From: earth

Quote:

Originally Posted by stumpy9011

I have a quite a distinct knock when the motor is cold in my 99 z28. Some have told me its normal.. and others say get it checked.
What mit this be.. just a general guess.

if it is only when its cold and goes away after a minute of running it is most likely piston slap... not a lovely sound but tons of ls1 suffer from it... doesnt seem to affect anything just kind of embarrassing starting up your nice car and it sounds like a diesel lol...

what the problem is is the pistons gm used in the ls1 are a short skirt piston for low friction but some of the pistons were undersized a tiny bit, and until they warm up they rock in the cylinder making that terrible noise.