Piston Slap

Ok I posted this in LS1 tech but didn't get any info from anyone so I hope you guys can help.

I am wanting to find out if anyone here in the forum has ever had there LS1 warranted for piston slap? And if so what did they do to fix it? I had mine warranted for piston slap about a week ago and they said they replaced the pistons with longer pistons. Has anyone here ever replaced there pistons on there own to fix piston slap? If so what did you have to do to fix it your self such as piston size or boring?

What really needs to be done to fix piston slap in an 02 LS1 Z28? Can it really be fixed just by putting longer pistons in or must the cylinders be bored out also?

And did piston slap ever come back after a piston size change? Here is the part #88984245 for the replacement pistons they used in my LS1. Are these the same pistons that are now being used in the 03 LS1 engines? Also what did GM change in its engines to fix piston slap for there 03 ls1 production engines? Is the bore size and piston size different now for the 03 ls1?

Well if anyone else has received these pistons for piston slap repair let me know how they worked for you or if anyone has got a different piston than what I got let me know how it worked for you.


I am curious because it seems my piston slap problem is coming back again after only driving a few hundred miles!!!! It was quite at first and I thought it was fixed but now it is getting louder like it was before!! So I need all the info I can get before I go back to the dealer. So if anyone has any info for me let me know please.

Here is an interesting website I found. www.pistonslap.com

A good course of action to take, is find out from service manager, in his words, what was done to correct the problem, even if gm foots the bill. Too many customers/vehicle owners are not concerned, over fix, when they do not pay the bill.

Then walk a few steps, over to the parts dept. and do a little investigating. Armed with part #s is invaluable.

FWIW, customers had problems with piston slap on vortec engines in their trucks, due to excessive piston/wall clearance, a few years back. Yes, mfr. admittance of screwups can be based on number of complaints. It was in the case of the 'noisey' vortec engines. Some owners, in order to get a legitimate fix, of engines, or replacement pistons, as you claim you got, had to literally blow their engines, to actually get the replacement. BTW, they (the vehicle owners) were also told, the noise was considered normal. Well, actually, that was not being dishonest, on the part of the dealer. That noise IS normal....when the engine is built with too much piston to wall clearance.

As far a 'longer' piston is concerned, (what did R. Miller once sing, 'short, but not too big around'?... :rolleyes: ) anyway, I literally, and without the least bit of doubt, have been lied to, eye to eye, by service managers. When it comes to money out of their pocket, anything, including questionable integrity, can be a 'tool' in their 'toolbox'. Longer pistons......sure.

Yup! It's normal. Here's a post from a.....well, let him tell ya:

cptterry Posted: Nov 14 2003, 09:09 PM

Member No.: 90
Joined: 14-November 03

It continues to amaze me the amount of people that fall into this never ending trap of attys attempting to convince the American public that they should push and prod the dealers and auto makers into spending millions of dollars on a normal condition.

I work for a GM dealer and am very much aware of this engine sound. Yes it is normal and does NOT affect durability of the engine. I have seen many very high milage engines that just keep on truckin with NO engine failures. Every engine has some type of niose to it. Come on people, an engine is a machine machines make noise. You want to keep pushing the manufactures to replace engines, repurchace vehicles YOU and I will pay the price!!! It cost $$$$ to replace engines. The only WINNERS in these situations are the Atty's that make money convincing YOU that they can make money forcing the factory into spending $ needlessly. I have heard plenty of NON American made engines that sound like old worn out sewing machines, no seems to cry about those! I have not had any engine failures in my shop that are at all associated with piston slap. If you really are concerned and GM offers you a component letter covering the engine past the warraty period, take it ... file it in you glove box you won't need to use it.


Edit: BTW, got this off the forum, thru the link provided above.