BruceBufferTA

iTrader: (1)

I just bought a 2002 Z28 W/32k. At a cold start up it has a slight knock (not real loud but noticable) and then after a few minutes when it warms up it goes away. A local builder said this is common with the LS1 motor because of Hypersetic Pistons or it could be a lifter. He said not to worry about it....well I am and I was curious to hear your guy's feedback.

FUN LS1

He was right about LS1 pistons slapping at startup until they warm up being common. If it was the lifters, the noise wouldn't go away after the engine warms up.

SOMbitch

iTrader: (8)

Some LSx engines have piston slap and some don't. The 01 & 02's seem to more commonly have it. It is just an LSx quirk and nothing to worry about...... And your pistons are a hyperteutic (sp?) alloy.......

RPM WS6

iTrader: (3)

The builder is right, this is piston slap and it's super common on LS1s, especially '01-'02. My '02 does this, it's very noticeable but it's never gotten any better or worse over the course of 10s of thousands of miles I've owned it.

I would not worry about this at all.

lt1pwr1

iTrader: (1)

Agree with everyone else. No need to worry. I have a 98' and it has BAD piston slap until it is warmed up then it is perfect.

black_sheep454

iTrader: (9)

Yep, just piston slap. If I had one that didn't do it I'd be more concerned, since it's such a common problem

udienow

iTrader: (18)

+1 to above posts. My 00 does this since I bought it with 39k miles.

ArcticMissile

My 01 does it as well nothing to worry about.

lt1formula275

my 02 sounds like a diesal lol its go good oil pressure and runs great i wouldnt worry bout it.

BruceBufferTA

iTrader: (1)

Ahhh deep breath! Thanks guys for the info. I can go on with my day now

blk/slvr02ss

iTrader: (21)

No problem @ all!!!!!!

egott_91

iTrader: (1)

Yeah, just piston slap. My brother's '02 SS has it pretty bad.

My '98 SS doesn't have it w/ 50K miles, but my stepdad's '02 35th Ann. SS w/ 7k miles has a slight slap.

ReApEr75

iTrader: (4)

Welcome to the world of Piston Slap.

MI-Z/28

What causes piston slap other than the motor being cold? And if the motor was ever apart what needs to be done to fix the issue?

pat-ls101

Nothing to worry about, My 02' w/ 63K on it does it bad on cold start up. Sounds like its going to fall apart! Its so bad she got pegged the name "slappy" LOL But, drive it for 20 mins and its quiet as can be! Doesnt consume any oil and makes around 20 passes a season! Also, my wifes 03' Yukon has it very slightly at cold start up....

FUN LS1

You wouldn't want to fix the issue... The pistons slap until they expand from the heat, so you can't just stick bigger pistons in there to fix the slap when it's cold.

caseypryan

iTrader: (10)

another vote for the piston slap. I've been told GM put the pistons in backwards in a lot of the LS family trucks and a coupes. They didn't do a recall because it doesn't affect anything except the slight noise on start up

02 wife

It's pretty common on 02's! I took my car back to the dealer with just 700 miles because of the piston slap. They said it was normal and perfectly fine. 80,000 miles later they were right lol! I really dont here piston slap anymore since the cam and longtubes, its just loud!

kevinolivo

i can hear/feel a knocking when im in park even when its warmed up. sometimes only when its warmed up. is this piston slap im hearing/feeling? its a 98 if thats relevant

dgcustomz

iTrader: (127)

yup! My wife's tahoe even does it on start up. I make her wait till it warms up so she can drive away.