Hello Guys/Gals. I'm new to this forum and so far I like it. I am posting in regards to piston slap in my '99 5.3 Silverado. Have not seen any posts on this...Mine started at about 10,000 miles. At that time the dealer said there was carbon on the bottom of the piston. GM was working on a fix. Then following year (this year), The GM garage said it is in fact piston slap and that GM is designing new/larger pistons. Should be available in April. I was told they are only replacing pistons, NOT short or long blocks. The pasted letter I have posted was given to me from the Service Manager. He was told by GM to give it to customers with the problem.They recommend not replacing, of course this would mean millions of trucks/suv's. They will replace if the customer insists. Mine is loud and lasts for alot longer than the 30 secs they say. Obviously it is only on cold start up. Being in Wisconsin that may be why it lasts longer.
I was thinking about trading it in but since 2002 is plagued also I passed. Then there is the new body style for 2003. I apologize for the long post but felt this was very important. Here is the letter:
Sorry couldn't get scanner to convert to a word type document so I"ll type it:
Engine knock on cold start

1999-2002 Chevrolet and Gmc C/K Pickup and Utility Models

2002 Cadillac Escalade (2WD)

with 4.8L,5.3L or 6.0L Engine (VINs V,T,U --RPO's LR4,LM7,LQ4)

Some of the above vehicles may exhibit an engine knock noise that begins in the first 12,000-15,000 miles of use. The knock noise is most often noticed during initial start-up and typically disappears within the first 5-30 seconds(may last longer in extreme cold temperatures). The noise is usually more noticeable on the initial satrt-up when the temperature is below 50 degrees and may be more pronounced on the first cold start following a long trip.

This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall. GM Powertrain Engineering, and an analysis of engines with this condition, has confirmed that the noise is not detrimental to the performance, reliability or durability of the engine.

 

Here's the rest. I hit return and it sent the post on me): THIS NOISE DOES NOT HAVE ANY EFFECT ON THE LONGEVITY OF ANY OF THE ENGINE COMPONENTS.

Important

At this time, attempts to repair this condition by replacing the engine assembly or pistons is not recommended.

I will e-mail the letter to whomever wants it or if they can get it to post on here.

 

[quote]Originally posted by Hotrodchevy:
<strong>Here's the rest. I hit return and it sent the post on me): THIS NOISE DOES NOT HAVE ANY EFFECT ON THE LONGEVITY OF ANY OF THE ENGINE COMPONENTS.

Important

At this time, attempts to repair this condition by replacing the engine assembly or pistons is not recommended.

I will e-mail the letter to whomever wants it or if they can get it to post on here.</strong><hr></blockquote>

Ask the dealer you talked to about the 3.1 liter engine in the new Malibu. They have a TSB on piston slap and they are replacing 2 or 3 of the pistons per motor to prevent engine failer. My father just had this done. There have been write ups on this problem.

Piston Slap Website

BTW, Welcome to the site <img src="gr_grin.gif" border="0"> <img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

 

We've had some cold weather here in Chicago the last few days and I may have noticed for the first time a possible piston slap problem.

Noticed it after about a 30 mile trip, truck was off for about 1.5 hours, then on start up heard something resembling piston slap for about the first 3 minutes. It could also possibly be just some clanging within the exhaust, at this point it is hard to tell. I can duplicate this noise (somewhat) by doing a brake torque and holding the R's around 800....this would be fully warm, which leads me to think it might not be.

Either way, why the hell does GM have such a glaring problem with engines and piston slap? Didn't anyone teach these fools how to properly clearance stuff and build a decent engine? If you ask me, the excuses and brush off attitude of GM on this issue is pretty pathetic.

 

[quote]Originally posted by Hotrodchevy:
<strong>Hello Guys/Gals. I'm new to this forum and so far I like it. I am posting in regards to piston slap in my '99 5.3 Silverado. Have not seen any posts on this...Mine started at about 10,000 miles. At that time the dealer said there was carbon on the bottom of the piston. GM was working on a fix. Then following year (this year), The GM garage said it is in fact piston slap and that GM is designing new/larger pistons. Should be available in April. I was told they are only replacing pistons, NOT short or long blocks. The pasted letter I have posted was given to me from the Service Manager. He was told by GM to give it to customers with the problem.They recommend not replacing, of course this would mean millions of trucks/suv's. They will replace if the customer insists. Mine is loud and lasts for alot longer than the 30 secs they say. Obviously it is only on cold start up. Being in Wisconsin that may be why it lasts longer.
I was thinking about trading it in but since 2002 is plagued also I passed. Then there is the new body style for 2003. I apologize for the long post but felt this was very important. Here is the letter:
Sorry couldn't get scanner to convert to a word type document so I"ll type it:
Engine knock on cold start

1999-2002 Chevrolet and Gmc C/K Pickup and Utility Models

2002 Cadillac Escalade (2WD)

with 4.8L,5.3L or 6.0L Engine (VINs V,T,U --RPO's LR4,LM7,LQ4)

Some of the above vehicles may exhibit an engine knock noise that begins in the first 12,000-15,000 miles of use. The knock noise is most often noticed during initial start-up and typically disappears within the first 5-30 seconds(may last longer in extreme cold temperatures). The noise is usually more noticeable on the initial satrt-up when the temperature is below 50 degrees and may be more pronounced on the first cold start following a long trip.

This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall. GM Powertrain Engineering, and an analysis of engines with this condition, has confirmed that the noise is not detrimental to the performance, reliability or durability of the engine.</strong><hr></blockquote>

I had a 1995 chev with piston slap in very cold weather starts. The problem was the block, it was honed in a slight cone. GM swapped the block.

 

My '00 Silverado had piston slap really bad. Once it was at operating temp, all was good. I never worried w/ it since I knew it wasn't hurting anything. My '01 GMC has a little slap on cold starts but nothing bad at all. As for my SS, it's so bad that it seriously sounds like I have a set of forged pistons! It's LOUD on cold starts, but it finally goes away once it's up to full operating temp. It certainly hasn't hurt my performance, and I'm not going to swap pistons just to possibly lose some HP from tighter tolerances. Just tell everyone that you have forged pistons for your 200 shot. <img src="gr_images/icons/wink.gif" border="0">

 

If it is really piston slap (too much clearance between the pistons and cylinder wall), its going to cause accelerated wear in the affected cylinders, increased fuel and oil consumption, the annoying noise and greatly reduced re-sale value. All getting worse as the miles accrue. Its also prevalent on the 3.1 and 8.1 Liter products from GM Powertrain as well. When GM tries to tell you its "NORMAL", take a look at their own illustrations of the damage piston slap can cause on GM TSB 01-06-01-005. You can see it and the other folks with this problem at http://www.gmpistonslap.cjb.net . Good Luck!

 

[quote]Originally posted by Pro Stock John:
<strong>Is it prevalent with the 3.1 V6? My 95 Lumina gets what sounds like piston slap in cold weather.</strong><hr></blockquote>

PSJ they have been replacing pistons on that motor. There is a TSB on it. My Father had some replaced on his 3.1 Malibu.

 

I sadly have a knocker as well. A 2001 2500HD with 6.0L engine. When we picked up truck from the dealer the salesman drove it up to the door for us from the prep area so it was running when we drove home. I thought he was just being nice - later I learned that wasn't the case. Next morning when starting in garage noticed the knock. Went back to dealer and was told by service manager, "we get two or three people in each week with the knock, a repair is supposed to be released around February 2002". The dealer (DeNooyer Chevrolet in Holland Michigan) wouldn't do anything for me and just pointed me towards BBB. They weren't much help either. Knock hasn't gotten significantly worse now at about 7,000 miles but is very noticeable and frankly embarassing considering its a new truck. Very discouraging when you spend $33,000 on a new truck and get stuck with this.

 

No problems here on my 01 5.3 GMC. Almost 20K on the odo. Cold weather, hot weather...nothing. Sounds like mine was built on a good day and time.