piston slap

[pm26]

Could somebody please answer this:

 

Did GM actually fix this problem? I have not been able to get a straight answer on this from anybody. I heard that they actually redesigned the pistons Then somebody said that they teflon coated the pistons. It appears that even some new '06 trucks have piston slap. This does not look to me like a fix, but rather as a really lame bandaid.

 

And if they redesigned and teflon coated the pistons, is this a permanent fix, or something that will only last until the warranty expiration date? What happens then? Yes, I know, NORMAL piston slap.

 

The way I understand it, the pistons in these engines must be closely matched tothe respective cylinder bores. This requires time consuming measurements and hand selection of pistons. So GM management decided that it is good enough to throw the pistons in without bothering to match-fit them, because it would cost too much. So, if you are really lucky and by chance your truck has pretty closely matching pistons, you have no piston slap. On the other hand, if you get one or more loose fitting pistons, then you have NORMAL piston slap. How can they tell people BS like this? So buiying a good truck has become a crap shoot?

[fossil]

Pretty welll all vehicles are prone to piston slap these days. Reason being is that modern engines no longer have piston skirts which makes the piston more prone to destabilzation in the bore at times.

[pm26]

You answered the question like a GM lawyer: GM did not fix the problem because it is not a problem and there is nothing to fix, i.e. all modern engines have it.

 

Thanks, but when I bought my truck, I was told that the problem has been fixed.

[mdub]

pm26,

 

You don't explicitly say in your post if you are experiencing the problem -- you only xpress concern about GM's "fix".

 

The fix you mentioned (teflon coating) was implemented starting w/ the 2003 models. As I recall, the piston skirt was also re-designed, the tolerances were tightened, and the teflon coating was added more as a safety measure.

 

As a result, I have not heard of the piston slap on any '03 and up engines, including my own. I also was very concerned about this problem, and the alleged (and way overdue in '03) solution, so I've paid a lot of attention to this issue. Of course, mine and other rigs are past the warranty period, and are not showing the problem that was frequently reported on '99-'02 vehicles.

 

If you're experiencing start-up noise, I honestly think you're the exception. I wonder if there may be something else causing the noise (valve train, etc.). It would be very disappointing if it was piston slap -- I hope that's not the case.

 

Keep us posted.

 

-Mdub

[Guest chevydeerhunter]

pm26,

 

You don't explicitly say in your post if you are experiencing the problem -- you only xpress concern about GM's "fix". 

 

The fix you mentioned (teflon coating) was implemented starting w/ the 2003 models.  As I recall, the piston skirt was also re-designed, the tolerances were tightened, and the teflon coating was added more as a safety measure. 

 

As a result, I have not heard of the piston slap on any '03 and up engines, including my own.  I also was very concerned about this problem, and the alleged (and way overdue in '03) solution, so I've paid a lot of attention to this issue.  Of course, mine and other rigs are past the warranty period, and are not showing the problem that was frequently reported on '99-'02 vehicles.

 

If you're experiencing start-up noise, I honestly think you're the exception.  I wonder if there may be something else causing the noise (valve train, etc.).  It would be very disappointing if it was piston slap -- I hope that's not the case. 

 

Keep us posted.

 

-Mdub

 

<{POST_SNAPBACK}>

 

 

 

I've got an '03 with the 4.8 and just over 30k on the clock and I can definitely hear piston slap in mine. It's become louder over the last 5k or so, but it's there at any temperature. It's acutally hacking me off more and more. I'm going to wait till it's paid off to buy a new Avalanche, but if they haven't fixed the problem by then, I don't know if I'll buy another GM truck.

[ProSport Tim]

I've heard the slap on the 03', 04', 05' and 06' GM 6.0 liter engines. My 5.3 does not do it...yet(14,000).

[jhm]

Could somebody please answer this:

 

Did GM actually fix this problem?  I have not been able to get a straight answer on this from anybody.  I heard that they actually redesigned the pistons  Then somebody said that they teflon coated the pistons.  It appears that even some new '06 trucks have piston slap.  This does not look to me like a fix, but rather as a really lame bandaid.

 

And if they redesigned and teflon coated the pistons, is this a permanent fix, or something that will only last until the warranty expiration date?  What happens then?  Yes, I know, NORMAL piston slap.

 

The way I understand it, the pistons in these engines must be closely matched tothe respective cylinder bores.  This requires time consuming measurements and hand selection of pistons.  So GM management decided that it is good enough to throw the pistons in without bothering to match-fit them, because it would cost too much.    So, if you are really lucky and by chance your truck has pretty closely matching pistons, you have no piston slap.  On the other hand, if you get one or more loose fitting pistons, then you have NORMAL piston slap.    How can they tell people BS like this?  So buiying a good truck has become a crap shoot?

 

<{POST_SNAPBACK}>

 

 

I do not belive they redesigned the pistons. The service manager at my dealer showed me a Teflon coated piston they took out of a '03 and the Teflon was almost totally spent. What you say about matching pistons to bore has been std op procedure at all engine makers for decades. I worked at a company in the early 80's and that is one product we designed and built-computerized piston classification gaging systems that would match a given piston od with a range of bore sizes. There is no need for hand selection. The piston slap is there because of the almost non existent skirts which were shortened to reduce mass thereby improving gas mileage. Some piston noise is more noticeable than others, but it is there in all engines. I've heard some pretty noisy fords and dodges too.

[lrymal]

No slap here on my '03 with nearly 100,000 miles and my '05. Forgive me but sometimes I think you guys are just hoping for problems.

[RyanZ71]

Someone slap GM!!!

 

[05Quadrasteer]

Call me dumb if you want but, what the hell is engine slap? I keep seeing these discussions about it but have no clue as to what it is or what I should be hearing to know if I have it.

 

Have a nice day.

 

Bill

[bigdogxx]

No slap here on my '03 with nearly 100,000 miles and my '05. Forgive me    but sometimes I think you guys are just hoping for problems.

 

<{POST_SNAPBACK}>

 

 

 

 

No i just think pm is extremely parinoid for some reason.Most of the post i see from him are either him mad at gm because he thinks theres a chance his tranny might let go if he tows something because mabey 1% of the trucks have tranny issues before 50k.And know he is worried about getting piston slap , really pm if your truck which has not even broke on you worries you to this extent why dont you just trade it in before anything might happen?

[pm26]

No slap here on my '03 with nearly 100,000 miles and my '05. Forgive me    but sometimes I think you guys are just hoping for problems.

 

<{POST_SNAPBACK}>

 

 

 

 

No i just think pm is extremely parinoid for some reason.Most of the post i see from him are either him mad at gm because he thinks theres a chance his tranny might let go if he tows something because mabey 1% of the trucks have tranny issues before 50k.And know he is worried about getting piston slap , really pm if your truck which has not even broke on you worries you to this extent why dont you just trade it in before anything might happen?

 

<{POST_SNAPBACK}>

 

 

 

 

 

I would not call it paranoid, but concerned. Maybe it was my neighbor with his failed transmission truck who caused me to worry for no reason (yet). No, I have not heard any piston slap in my truck yet, but then I have under 2K miles so it's way too early. I do not have any fortune tied up in this truck, and it is not my everyday driver. Besides I have other more important things to worry about than a truck that MAY one day have a problem. Seriously, I may sound like I cannot sleep because of this vehicle, but believe me, this is not the case.

 

There is a lot of knowledgeable people here and I ejoy reading most responses.

[diverlloyd]

No slap here on my '03 with nearly 100,000 miles and my '05. Forgive me    but sometimes I think you guys are just hoping for problems.

 

<{POST_SNAPBACK}>

 

 

 

 

No i just think pm is extremely parinoid for some reason.Most of the post i see from him are either him mad at gm because he thinks theres a chance his tranny might let go if he tows something because mabey 1% of the trucks have tranny issues before 50k.And know he is worried about getting piston slap , really pm if your truck which has not even broke on you worries you to this extent why dont you just trade it in before anything might happen?

 

<{POST_SNAPBACK}>

 

 

 

 

 

I would not call it paranoid, but concerned. Maybe it was my neighbor with his failed transmission truck who caused me to worry for no reason (yet). No, I have not heard any piston slap in my truck yet, but then I have under 2K miles so it's way too early. I do not have any fortune tied up in this truck, and it is not my everyday driver. Besides I have other more important things to worry about than a truck that MAY one day have a problem. Seriously, I may sound like I cannot sleep because of this vehicle, but believe me, this is not the case.

 

There is a lot of knowledgeable people here and I ejoy reading most responses.

 

<{POST_SNAPBACK}>

 

 

 

In defense of pm, although I don't have piston slap in my engine, I know a couple of other guys who have and I think it's bogus for GM to be TEFLON coating pistons. What the hell is up with that?

[pm26]

Call me dumb if you want but, what the hell is engine slap? 

 

<{POST_SNAPBACK}>

 

 

 

It's something you do to your engine after you've worked on it for 10 hours and it still will not start.

[lrymal]

... I think it's bogus for GM to be TEFLON coating pistons.  What the hell is up with that?

 

<{POST_SNAPBACK}>

 

 

Simply put, every manufacturer is seeking ways to improve gasoline mileage, yet keep emissions in check. Decreasing the mass (weight) of the piston is part of the method, and that is done partly by decreasing the skirt size. Every manufacturer is doing this.

 

A problem with the skirt being shortened (no joking!!!) is that the piston can possibly wobble very slightly, but it can produce a noise. A longer skirt (old design) has far better stability. But, the slight wobble is not going to hurt anything. To decrease the effects of the wobble, teflon has been placed on the skirt and basically, as I understand it, this is just to decrease the noise, that is, the slap.

 

This is not a GM issue at all. But, what has created a major issue is the internet and a side-industry. Lots of class-action law suit websites love getting into this sort of thing. These are the same guys who also attempt lawsuits regarding "deathkool". They create amazingly convincing websites and we get sucked into it.

 

Armed with photos show-casing blown engines, pistons with worn-out teflon, and burned up components, it is easy to get worked up over it. The same website authors are involved with the DeathKool arguments and both kinds of sites will have contact information "in your state" for the lawyer involved in the class-action lawsuit. Take your pick, there's bunches of lawsuits about these two issues.

 

To compound it even further, there will be quotes from certified mechanics explaining just how sorry the whole state of affairs is, and that manufacturers are taking shortcuts, "ruining good motors with teflon-plated pistons" being one of the examples.

 

And so, there it is. As Ripley sez, BELIEVE IT OR NOT.

 

My take on the whole thing? These are good trucks. I don't care for most of the dealers, but these are great trucks. I have used the heck out of my '03 and totally enjoy my '05.