How do I QUIETEN piston slap?
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 858
Likes: 10
From: Chandler AZ
St Jude Donor '14
How do I QUIETEN piston slap?
I have a 01 Vert for Sale. Has 90K and hella piston slap. Everybody thinks its knocking and they do not believe me when I say its normal in alot of GM engines. I want to temporarly quiet it down. HOW?????
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 858
Likes: 10
From: Chandler AZ
St Jude Donor '14
Tech Contributor
Joined: Jan 2007
Posts: 19,425
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From: Dyer, IN
How do you propose to make up for a disparity in piston to cylinder bore tolerance? Have to just let her warm up, things expand, noise dies down. I guess you can make sure the engine is good and warm before a prospective buyer comes over. An educated C5 buyer should know the difference, but no one wants to try to listen for potential issues over the din of piston slap, when they are considering the car for purchase.
Last edited by lucky131969; Mar 24, 2009 at 11:40 PM.
Drifting
Joined: Feb 2007
Posts: 1,993
Likes: 7
From: LaPine Oregon
cold start piston slap?
Owners of LS1/( & '01 LS6 engines )have complained to GM since 1997 about cold start piston slap or knock anomaly. It is not a durability issue, according to GM. But the issue was addressed with the addition in May of 2001 on the LS1 to the 2001 M/Y production line with a revised piston that decreased the dimension between the piston and cylinder wall plus the addition of an anti friction polymer coating on the piston's skirt. ( This was also added to the LS6 M/Y production line in mid April of 2001).
The noise should go away as the engine reaches operating temperature.
The noise should go away as the engine reaches operating temperature.
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Brett Foote
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
While a pain, I would think you are better off being honest about it rather than covering it up only to have the new owner find it later after the sale. I just gave my Pontiac Grand Am to my neice's husband that had piston slap since new in 1994. Well beyond 200,000 miles and still runs like a raped ape. Only thing you can do is tell the buyer that it is typical of the motor manufactured within a time window and hopefully you will find someone who knows this to be the case.
Melting Slicks
Joined: Oct 2007
Posts: 2,464
Likes: 2
From: Cedarburg, WI
While a pain, I would think you are better off being honest about it rather than covering it up only to have the new owner find it later after the sale. I just gave my Pontiac Grand Am to my neice's husband that had piston slap since new in 1994. Well beyond 200,000 miles and still runs like a raped ape. Only thing you can do is tell the buyer that it is typical of the motor manufactured within a time window and hopefully you will find someone who knows this to be the case.
Not a good idea to try and cover it up for the sale!! 
Tech Contributor
Joined: May 2008
Posts: 3,100
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From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
I'm in total agreement with the others. Trying to cover up the noise, and not being honest about it, will more than likely come back to bite you in the a$$.
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 858
Likes: 10
From: Chandler AZ
St Jude Donor '14
I agree with you all and thats what I have been trying to do but IT WONT GO AWAY(meaning it won't sale!). So how is something suppose to bite me in the a$$ when it doesnt go away in the first place!!!!!
Racer
Joined: Sep 2005
Posts: 383
Likes: 0
From: Michigan
As I see it you have 5 options
1. fix it. (you will never recoop your money with this one)
2. Trade it in to a dealer
3. lower your price
4. keep the car
5. take it to an auction
It's tough out there right now many people are having trouble selling thier vettes for a good price.
1. fix it. (you will never recoop your money with this one)
2. Trade it in to a dealer
3. lower your price
4. keep the car
5. take it to an auction
It's tough out there right now many people are having trouble selling thier vettes for a good price.
Le Mans Master
Joined: Sep 2007
Posts: 7,604
Likes: 8
From: Belleville Il
While mine does not have SERIOUS slap,it is noticeable. I have made some cold morning observations that you can pass along. I placed the DIC on oil temp,,and have noticed on mine that it starts to go away when the OIL temp reaches about 80 degrees,,and is pretty much gone in a few more degrees!! Oil temp is a little more accurate indicator of the piston/block relative temperature. Try it yourself on the next few fullly cold motor starts and check it out. Then you can tell them to just drive easy to that point. There are motors out there with 100s of thousands miles that have done it from day one. Since most vets are driven in nice weather it is not a big problem for the wait!! On 18* mornings 80* takes a bit longer
!!
!!
Tech Contributor
Joined: May 2008
Posts: 3,100
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From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
Any attempt to TEMPORARILY QUIET IT DOWN, in order to make a sale,
is DECEITFUL.
Melting Slicks
Joined: Feb 2006
Posts: 2,172
Likes: 104
From: Des Moines Iowa
It's NOT normal in LS1 engines that are warmed up. If the piston slap only occurs when the engine is cold, suggest you copy / print the GM service bulletin that addresses this issue, and show it to prospective buyers.
