piston slap?

I was wondering what exactly piston slap is, I hear a lot about it here


1998 Camaro Z28 M6, a few mods

An over-bore in cylinder 1(pretty sure it is #1). There is a little play in it and it doesn't go away until it is warm and everything expands and it goes away.

don't know to much about the internal workings of an engine, what is overbore and how does it happen (causes)

My started having piston slap at 1500 miles and now at 3600 it it worse and it doesn't go away after warmup. Bore is the size of cylinder. Basically the bore is to big so the piston is moving around until the piston ring expands from heat then it goes away, but not always. I'm taking my car in next week for a factory cosmetic flaw and I mentioned to the service manager about the piston slap. If I knew about this before I bought the car I would have never bought the car. If I become one of the very unlucky few to have very loud piston slap then I'm getting rid of this car. :mad:

thanks a lot for that info, also, is it a factory defect or does it start to happen b/c for another reason?

My 01 Trans Am has had piston slap since brand new, and now has 35,000 miles. Hasnt caused a problem for me, it goes completely away after the engine reaches full operating temp. I think a lot of people blew the issue way out of proportion... the two GM cars I had prior to the TA also had piston slap (and my 90 Cadillac Coupe De Ville had rod knock) all went 150,000 trouble free miles. Its a performance engine, it wasnt meant to be a Lexus. Furthermore, its an F-body... I knew what I was getting before I signed the papers, and I was willing to accept the problems and noises for the awesome power and reliability of the LS1.

Originally posted by blacknight
My started having piston slap at 1500 miles and now at 3600 it it worse and it doesn't go away after warmup. Bore is the size of cylinder. Basically the bore is to big so the piston is moving around until the piston ring expands from heat then it goes away, but not always. I'm taking my car in next week for a factory cosmetic flaw and I mentioned to the service manager about the piston slap. If I knew about this before I bought the car I would have never bought the car. If I become one of the very unlucky few to have very loud piston slap then I'm getting rid of this car. :mad:

If it is really bad and does not go away at normal operating temp make them replace it. If they say no tell them you are going to go to the better business bureau.:)

A few months ago, I posted a topic relating to noises that I found while the car was running. I described the noise as best I could - that of a supercharger whine. Plainly put, it sounds like a supercharger whine. However, it doesn't make the noise all the time, and it usually occurs when I'm at the higher rpm's (3500+).

A few suggested the noise coming from my alternator, proposing that it may be giving out, while a few others suggested "piston slap". For the record, I never had it checked out because I noticed occuring less once I put more power steering fluid in (I was very low and didn't even know it!). However, as my car has been going through more and more miles, I notice the noise has return yet again and no, my power steering is fine.

Could this be "piston slap"?

Also, is this covered by the defect warranty? I have the GMPP warranty but a $200 deductable...

If it's not going to kill my car then I won't mind, but if it is...let me know. :cry:

I'm just worried because the rattling noise has gotten much more noticable in just the last month. It isn't real loud but I've heard that with piston slap it just gets worse over time. I know this is no Lexus but at least GM should take responsiblity for this and fix the cars that are making lots of noise and fix the problem from happening again in future LS1's. If mine gets much worse then I would demand for a new motor which would suck because I'm still waiting for mine to get stronger. Heard 10k is when the LS1 is totally broken in. At least in CA where I live they are real anal about cars dealer problems and shops and take these matters very seriously.

wow this is unusual. i know that this was a big problem for the 98-00 ls1's but in 2001 gm was suppossed to put in different rings to correct this problem and this is the first time i've heard of this happening in a 2001 or newer. all i've got to say is hope i don't have this happen to me and i hope all you guys have good luck getting the problem fixed.

Originally posted by tainted
once I put more power steering fluid in (I was very low and didn't even know it!). However, as my car has been going through more and more miles, I notice the noise has return yet again and no, my power steering is fine.

Could this be "piston slap"?



I would have the power steering pump checked out, Piston slap sounds nothing like a whining PS pump in my opinion. My beater car sounds like it has a supercharger when it gets really low on PS fluid, because it is cavitating the pump. Look at the fluid after it has been running a while, does it have a lot of bubbles in it? There have been times that I opened the power steering reservoir on my regal and it looked like foam in it, but had absolutely no effect on the drivability of the car. The power steering feels fine. If you ran your car very low, the pump may have been damaged.

Originally posted by bsmith
If you ran your car very low, the pump may have been damaged.

How and why would this happen?

My PS leaks and whines a little.

Originally posted by tainted
How and why would this happen?
I am by no means an authority on power steering pumps, but I have taken hydraulics classes. I am pretty sure that the power steering fluid acts as a lubricant for the power steering pump as well as providing the hydraulic pressure for the steering. If you run low on fluid, you cavitate the pump. The vanes inside the pump could wear out and damage the pump. As far as how it could have happened, I dont know, check the lines to see where you are losing fluid. Does your car have a power steering fluid cooler? Check those lines if you do.

If I am off base on this, I am sure I will be called out by someone, I am just giving you ideas so you dont have to go to the dealer.

Originally posted by z top
wow this is unusual. i know that this was a big problem for the 98-00 ls1's but in 2001 gm was suppossed to put in different rings to correct this problem and this is the first time i've heard of this happening in a 2001 or newer. all i've got to say is hope i don't have this happen to me and i hope all you guys have good luck getting the problem fixed.

Does anyone know if those of us who got LS6 blocks in our Camaros also got the tighter clearance pistons? If so, are these any less likely to have slap? I've only got 600 miles so far, and it's quiet.

http://www.pistonslap.com/

Originally posted by pg318
Does anyone know if those of us who got LS6 blocks in our Camaros also got the tighter clearance pistons? If so, are these any less likely to have slap? I've only got 600 miles so far, and it's quiet. Interesting article:
www.idavette.net (http://www.idavette.net/hib/02ls6/page5.htm)

Originally posted by pg318
Does anyone know if those of us who got LS6 blocks in our Camaros also got the tighter clearance pistons?

how did some of yall get LS6 blocks in your f-bodies? was it an option? would changing rings help the problem? not that anyone would want to go through all that trouble instead of havin the dealer put in a new motor but just out of curiousity.

Originally posted by Rippin92RS
how did some of yall get LS6 blocks in your f-bodies? was it an option? would changing rings help the problem? not that anyone would want to go through all that trouble instead of havin the dealer put in a new motor but just out of curiousity.

10-15% of LS1 fbods in 01 and 25% of them in 02 got the LS6 block. Nobody really knows why though.:confused:

Originally posted by TransAmLS1
10-15% of LS1 fbods in 01 and 25% of them in 02 got the LS6 block. Nobody really knows why though.:confused: Yeah, they know why:
LS6 Block (http://www.members.cox.net/jfcooke/images/LS1-LS6.jpg)