engine detonating (knocking)

[starbird]

YES, many of us have the same problem with our Chevy's!!! The website "pistonslap.com" is still running and is very informative....drop by and look it over.

As for the knock/ping being "Normal"....well, I've seen what that causes in the bores of the block....it is NOT normal at all! It appears we have all been cheated by GM and I don't think they will be made to pay up....as much as I love my chevy, I see a Ford or Dodge in my future....

[dk 55belair]

you know guys, i love my truck but this rattling and peckiing is for the birds. i paid 24 grand for a 01 silverado last may, i fought with gm, at only got the extended warranty, which is not transferrable and hurts the resale of the already knocking truck.
i hope gm reads this letter, because i have rededicated my efforts in to making sure that know i cross paths with buys a gm car without knowing how shitty they are doing us loyal chevy truck owner, so far i guess i have stopped twenty folks from buying a new gm product. i just wish i would have had someone to tell me chevy truck engines are shit and the man that warrantys them is chicken shit! after 26 years i will never buy another chevrolet or gm for that matter, but that doesnt bother gm, because it looks like their corporate has a five year plan to run them out of business.

[1991FZR600]

My 2003 5.3L Silverado runs fine so far. (5,500 miles), I do drive with my fingers crossed. I feel for you guys, I can't imagine spending all that money and not having a perfect product. My truck has ripples down the rails on top of the box. Since it is double-ply there they can't do paintless dent removing. I didn't want my new truck filled, sanded, and repainted yet so I didn't fix it.

They fixed the knock in 2003.

Chevy gave my dad a free 100,000 mile warranty on top of his standard 3 year warranty on his 2001 5.3L Silverado.

[TXAGG05]

I take it your dad's 2001 had the knock?

I listened to the noise on Pistonslap.com and my 2002 5.3 makes a similar noise sometimes when I start it, but only for about 15 seconds, and I can't hear it in the cab with the doors closed...Could this be the piston slap?
I wouldn't hesitate to get the buy-back and buy a Ford.

Thanks,
Jeb

[RABarrett]

These complaints sound similar to the ones I dealt with when I was a driveability tech in the '80's and '90's. Do you refer to what is called "trace' knock during light acceleration that quickly disappears or to a noise audible over the radio that does not stop? Have you tried different grades and brands of fuel? In some cases, it is possible for one brand of fuel to have a lower octane rating than another with the same grade posted. Is this an issue which gradually formed of something present since the vehicle was new? Please advise. Ray

[1991FZR600]

We've finally gotten an answer on the cold-start piston knock involving 4.8, 5.3 and 6.0-liter V8's in '99 to '02 GM cars and trucks. General Motors has previously released a Technical Service Bulletin explaining the condition that occurs after approximately 12,000 miles and a normal accumulation of carbon above the top piston ring.

I spoke with Sam Winegarden, GM program manager and chief engineer for small- and big-block engines. Sam explains that following extensive testing, General Motors is confident the start-up noise will have no adverse effect on performance or durability of the engines involved.

As opposed to the larger pistons of earlier design engines, today's technical refinement requires the use of smaller pistons to reduce weight and reciprocating mass in order to aid in efficiency and durability. This reduction in size also reduces the stability of the piston in the cylinder bore, which can promote piston noise.

Preliminary testing on these engines showed no sign of a problem, but, as in many other situations, the symptoms came to the surface after the vehicles were subject to normal driving conditions.

The manufacturer's stand on the issue is that it doesn't warrant a service bulletin or recall promoting a repair. We were also assured the problem has been corrected on the '03-model line with a piston-design modification along with the addition of a polymer coating.

My response was from the viewpoint of a consumer who purchased a brand-new vehicle that developed a notable engine knock before the first major service. The complaint was not only about the annoyance of the condition, but also the effect on resale and depreciation.

The answer was that General Motors would be dealing with the consumer on a case-by-case basis, and complaints have been resolved by means of warranty extension and parts replacement.

The owners of involved vehicles exhibiting the cold-start piston knock should have the service manager of the GM dealership, which has been evaluating the noise, contact the manufacturer's zone representative. Hopefully you can come to satisfactory terms.

[jtucker]

I have a 2002 Chevy Silverado that has the same problem. The dealership says GM recognizes the problem and has no plans of resolving it. I suspect that we will all be walking as soon as the warranty expires. I also have a 2002 SS Camaro that sounds like a symphony of knocks. I'm about to take it in...I'm sure I'll hear the same thing about it. It's a shame to spend that much on a vehicle for that eh?

[dk 55belair]

Originally Posted by jtucker

I have a 2002 Chevy Silverado that has the same problem. The dealership says GM recognizes the problem and has no plans of resolving it. I suspect that we will all be walking as soon as the warranty expires. I also have a 2002 SS Camaro that sounds like a symphony of knocks. I'm about to take it in...I'm sure I'll hear the same thing about it. It's a shame to spend that much on a vehicle for that eh?

Dont know if you were aware that GM wont fix your engine but if you raise enough hell, and send the better business bureau an email, then GM will extend the warranty on your engine to 6 yrs or 100,000 miles. It's a little bit of help, atleast until a class action lawsuit gets start. Which I want to be a part of. GM has no clue how much loyalty this is costing them. I personally have stopped three people that were buying new GM trucks, just by telling about my nightmare knocking truck. It will bite them, just wait. dk

[frankendart]

Right!!!!!

[BadBoy1404]

I have a 2000 Chevy 5.3 and I have never heard a knock in my life. It starts excellent every time and i let it warm up for about 5 minutes before driving away. I heard that the 5.3's as well as other vortecs have bad knocking problems so i run premium fuel with Zmax cleaner every other oil change. It dramatically reduces carbon build up. For the people with piston slap, Im sorry and the best of luck to you trying to get compensation.

[remencin]

Do you guys remember back when you were dating your wife.... the first time she flew off the handle. You thought you were pooched right? Wonder "Gee do I really want to be with her?" What you are experienceing with your trucks is no different. I work at a dealership.... no please don't dismiss what I am saying because of that.... But first of all I have never seen one of the engines fail other then on where the oil was not changed for 35000 miles. We have customers that have upwards of 200 000 miles on their trucks and they have had no problems what so ever. I have personally taken apart one of the high mile engines and you could still see the cross hatch in the cylinder walls. Sometimes there are other factors that explain things... Has anyone ever talked to an engineer about this? Mass plays a big factor in the acoustic quality of a component. Maybe there were other noises that helped cover up that noise... ie... louder fans... louder exaust. If you do some research you will find out that the grass is not always greener on the other side of the fence. Toyota for instance covers up this noise in a very tricky way. They derate the engine during warm up... manipulate timing and fuel. Only one the engine is warmed up do they give you the rains to all the ponies under the hood. If you don't believe me do some research yourself. This is a documented fact with a related TSB... SAE also has papers published related to this means of controling noise. Has the General hung you out to dry in the past? Judgeing from the die hard loyalty most of you have shown in the past I would say no. They have built you great trucks in the past. Why get distrustful now? Do you have a documented complaint? If the answer is yes... don't worry about it... if things do go south you do have legal recourse. But until that time comes, that time when your gm actually makes you walk, don't you think its a little premature to make judgement?

Just my 2 cents

[frankendart]

The problem is multifold:
1. Gm has released a potentially defective engine. Some estimates put the piston slap issue at as high as 30% of Vortec engines. If that true, that very high.
To pay $30,000+ in many cases, and have a gas engine knocking like a diesel is not "a good thing".
2. For 3 or 4 model years GM denied that piston slap existed. While customers were complaining about a real problem, GM was saying there was no problem. What the dealers were doing about it was another question.
3.GM was offering free 100,000 mile bumper to bumper warranties to try to satisfy customers who had trucks with piston slap, they excluded piston slap in their coverage.
4. It became necessry to go to court to have your vehicle repaired under warranty.
5. Gm offered replacement engines for 6.0L owners, and free piston replacement for 5.3L owners. Quite a step for a problem that "doesn't exist".
6. The biggest problem became an issue of trust. Those people who felt, wrongly or rightly, that they had been given the runaround by GM developed trust issues. I can't say that I blame them.

You comments are probably a little biased simply because you get paid to do what ever you do at the Chevy dealer. What you need to know is this; Not ever Chevy dealership does evertyhing it can to help the customer. While this might not be an issue at the dealer you work for, it is not uncommon for dealers to not service their customers completely, and to their fullest extent. It's just a fact of life.
Unfortunately for many of us, most dealers put profit above customer service. It's like that on the sales side, and it's like that on the service side. The reason the dealer is there is simply to make money. In the case of new car dealers, they meet that purpose by selling and servicing cars. If they can do that, meet the 80/20 rule, and make a profit, they will be there tomorrow.

Peace...

[wgrep]

Mine has been doing this since about 10000 miles, just like the bulletin says after a cold start when engine is running get a piston skirt noise that sounds like a rod knocking except that it goes away as the engine warms
noise lasts less than one minute and only on cold starts. I can assure anyone that the normal noise I have is completely harmless as I drive this engine hard and have for over 100000 miles now. and if this was an engine destroyer mine would have been destroyed long ago. this engine regularly sees 11000rpm for extended periopds and just won't blow up.

I think I'll tear down my Porsche and increase the skirt clearance maybe I'll be able to outrun my truck