engine detonating (knocking)

Anyone out there having similar problems with their Chevy? I've got a 2001 Chevy Silverado, short wheel base, 4.8 engine...and I cant get rid of this problem. I took it back to the dealer, but no such luck. They say it checks out okay. However, they are wrong!
Some other symptoms are a very rough idle along with the knocking. This is a new truck, only 20,000 mi. Im confident that Chevrolet makes a great truck, but want to fix this problem.
I've tried different grades of gasoline, but still...nothing!

My daughters 2001 Tahoe, is having the SAME problem!

Get back with me if you have dealt with this, or have any suggestions.

Thanks.
DC

Please advise on the outcome of your problem with the engine knocking. I am familiar with other similar vehicles that began using oil after only a few thousand miles. Also, has your dealer provided you with any paperwork from GM about the known problem? Thank you for your response.

Yes. I have had the same problem. I have a 2002 extended cab with the 4.8 also. Truck has about 18,000 miles on it. I took it back to the dealer just last week about the knocking and they replied that it is "normal" with "these" engines. (Which got my curiosity up) I tried to get some info out of the servce manager, who said some thing about teflon coated pistons being what made the knocking.? As with the previous post keep me in the loop.

Thanks
SEM

I have knock on my 2001 Suburban's 5.3l so keep me in the loop if anything happens, too. More than likely, it won't get resolved and I'll just end up buying a Jap car next :(

I have a 4.8 as well. Mine knocks and pings has no power, and gets horable gas mileage. I have talked to several dealers in town and they say that it is characteristic of that motor. I will have to have the fuel system cleaned every 20,000 miles and it will still do it. Detroit said the same thing. Has anyone found a fix yet?

Yup, I have a 2000 with a 4.8 L and the dealer told me it was a characteristic of this engine.

MC

Is there a solution to this problem?

GM has been back and forth with this condition right now it is at the point of no repair available! No planed repair at this time but that could change. The new model trucks have been redesigned as far as I been told.

yeah I've got it too on my 02 silveraado. i love my 4.8 truck, don't get me wrong. i get 25 mpg highway, but she's got a little ping to her. i know a lot of trucks have it, and i'm going to try my luck @ the dealership. I have 22k on it, and have loved every mile. even if they turn me down, i won't go to another truck. after less than a grand of bolt-ons, she smokes the tires right off the line, and the mustang gts look pretty in the rear view. the only cure i've found for the knock is louder pipes. LIKE A KNOCK! :smile:

Change the igintion leads with new ones (original one's) it will fix that:bigthumb:

Wow. I'll try it. Thanks romatic. Do you recommend any certain brand? Did your pickup have this condition? Thanks again.:iceslolan

Yes... i have same your condition and my be worse , use AC delco wires they are the best and please let me know if that fixes your problem :cool:

WOW WOW :dogpile: :bigthumb: that works great.... I replaced the leads and gone... gone going.... no more Knocking here... HEA.....

Thanks

you guys should go to napa or some other place and get this stuff called sea foam. its a gas additive....just pour it in your tank when you fill up. i know alot of people that have said that it works for them (no more knocking, engine runs smoother, etc.). ive also used it in my car too and it works like a dream

my 01 Z71 knocks so bad it sounds like a rod is going through the oil
pan. I have heard the same as all of you, normal noise etc.

Are you fellas talking about PISTON SLAP? If so, save your money. It's not a problem with bad gas, or anything like that. It a piston problem.
The piston has a short skirt, and, is actually a little small for the cylinder bore. When you start your truck, it sounds like a diesel. Usually, once it warms up the slap will go away because the piston expands as it gets hot.
GM claims that it "NORMAL" and "HARMLESS" to the engine. I just can't imagine how a piston wobbling and knocking against the cylinder wall a couple of thousand times a minute could be normal, much less harmless. :confused:

I've read that the cylinder walls are pretty well scored by this when they tear down the engine. I've also read that trucks with this problem suffer from poor resale value, too! That makes sense. I know I would buy a truck that sounded like that. Would you?

I understand that the '03 trucks are supposed to have been cured of the problem. Tefloned pistons are supposed to stop the noise.

You have to wonder why GM would spend the money to try to fix something that is suposed to be "Normal and Harmless", though....

Just my humble opinion.
Frank

my 01 Z71 knocks so bad it sounds like a rod is going through the oil
pan. I have heard the same as all of you, normal noise etc.
my 2001 silverado with 35,000 miles knocking and im recieving the same runaround from the service dept and gm. does anyone know if a class action lawsuit has been taken against chevrolet. i want in. for 26 yrs ive drove chevys and own 6 right now, im so mad i cant stand it.

does anyone know if a class action lawsuit has been taken against chevrolet. i want in. for 26 yrs ive drove chevys and own 6 right now, im so mad i cant stand it.


I haven't heard anything about a class action law suit. There was a web site that covered piston slap, and had link to lawyers. I suppose that was the beginnings of a class action, but the site was shut down by the courts. I think GM had something to do with that(?).

Many Chevy guys are finding that thier new (99-03) trucks have more comfort and drivability, but the VORTEC engine is not as good as the good old 350 was. I own a 2000 Silverado, and while it's appointed much better than any p/u I've had in the past, I wish it had a 350.

I find myself trying to figure out why GM would design an engine with the potential for something like piston slap. It seems to me that someone in R&D would have known the the VORTEC had a problem, long before the engine was put into production.

My opinion is that R&D knew there was a problem, but the bean counter, the guys with the check book, who really run GM, made the decision to go ahead with it anyway, because of the dollars already spent. The gamble was that only a fraction of the engines would develope a problem, and of those, only a smaller fraction of people would open a law suit about it. Still a small number would win their law suit.
It was a calculated risk, and so far, it would seem that they were right. GM has produced defective engines, and no one has held their feet to the fire for it.

While my Silverado does not have a slap problem, and it now has 80,000 miles on it, I do know two people who's trucks suffer from piston slap. Neither of them have recieved any help from GM, and they can't sell the trucks for anything near what they should be worth. It's truly a shame, and I feel truly sorry for them. They are both diehard "CHEVY-GUYS", and GM is doing nothing to pay back the decades of loyalty both these men have shown.:shakehead

I'll be looking for a new truck when the '04's come out. Because of GM's lack of response to the problem, I'm not sure that I want to RISK another $25,000 to $30,000 dollars on another Chevy. For the first time in my life, I'm actually considering buying a Toyota :uhoh: !!! I've heard and read all the pros and cons about the Tundra, and the pros far out weigh the cons. I know a few people who own Tundra, and all of them rave about the trucks. Most of them are former Chevy buyers. There must be something to it!

Last night, during a conversation about what my next truck will probably be, my buddy (a life long Chevy buyer, and a former '01 Silverado owner) told me that he had, "...forgotten how good it feels to own a truck as dependable and trouble free as his Tundra". I've found that that's the typical response from Toyota owners. I remember when it used to be what Chevy owners said. :eek7:

That's my :2cents:

From the GM Technical Bulletin on the subject....

Info - Engine Knock on Cold Start #01-06-01-028
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 -- RPOs LR4, LM7, LQ4)

Some of the above vehicles may exhibit an engine knock noise that begins in the first 19,000-24,000 km (12,000-15,000 mi) 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 start-up when the temperature is below 10°C (50°F) 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. 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.


Please share the information found in this bulletin with customers who inquire about this condition. In the event they have additional questions, please have the customer contact the Area Service Manager.

:mad:

Here is the latest bulletin on the topic. My brother, best friend, my two uncles and I all own newer Silverados. My one uncle has a newer 2002 that does not have the problem. Everyone else does. One GM mechanic told me that it is the lightweight, short skirt design of the piston. It is short enought to twist slightly and slap, especially when carbon build up and the engine is a little cooler. It is a really bad design because if there is a real problem like a bend rod, crooked lifter bent valve or the like, you would just be told that it was a normal sound and you'll just have to live with it. I've got 80,000 on my truck and it still runs fine. I would be interested in hearing from someone that there engine blewup because of that problem.

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 -- RPOs LR4, LM7, LQ4)

Some of the above vehicles may exhibit an engine knock noise that begins in the first 19,000-24,000 km (12,000-15,000 mi) 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 start-up when the temperature is below 10°C (50°F) 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. 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.


Please share the information found in this bulletin with customers who inquire about this condition. In the event they have additional questions or concerns, please advise your Area Service Manager.

guys they knock because they either aren't getting tje octane they need or because your timing is advanced to far. so if a fuel additive doesn't fix the problem go to an auto parts store and rent a snap-on timing light and down you dwell and timing. also it might be your points (if your using an old distributor) but those take some time to get back in the right spots. and if you dont know what your doing its a real bitch! so i would advise against playin with those.....hope this helps boys!

guys they knock because they either aren't getting tje octane they need or because your timing is advanced to far. so if a fuel additive doesn't fix the problem go to an auto parts store and rent a snap-on timing light and down you dwell and timing. also it might be your points (if your using an old distributor) but those take some time to get back in the right spots. and if you dont know what your doing its a real bitch! so i would advise against playin with those.....hope this helps boys!


Points? Distributer? :confused: These trucks have neither.

My buddies truck is serviced by the local Chevy dealer. If they can't get it right, who can??? His truck suffers from piston slap, not low octane knock. He runs 97 octane gas, and has since he bought the truck.
*He's had it "DECARBONIZED", to no avail.
*He was instructed by the dealerdhip to change the brand of oil and filter he uses. But, since the Chevy dealer does his oil changes, he left it to them to use the "right stuff".
*The dealership mentioned the higher octane thing, but he already uses premium gas.

He told me that one of the techs at the dealership mentioned replacing the pistons with teflon coated pistons. That has not been done yet, but all of the other so called "cures" have. He's extremely unhappy with his truck, and I can.'t say that I blame him. It sounds like a diesel!

It's not a distributer problem, or points, or octane, or timing, or anything like that.

It was explained to us by a GM tech that, the piston, when cold, is actually too small for the cylinder bore. That, coupled with the very short piston skirt create a "piston slap" situation during cold starts. The piston actually wobbles in the cylinder bore, and the bottom of the piston, the skirt, "slaps" the cylinder wall, thereby make the knocking sound. As the engine temperature rises, the piston swells enough to fill the bore and reduce or eliminate the slap. Now, I'm not a GM technician, nor do I claim to be a master mechanic. But, that explaination makes sense. As does the theory that along with slap comes scoring of the cylinder wall. doesanyone think that a piston can wobble in a cylinder a few thousnad times a minute, and not cause some kind of damage to the cylinder wall, or piston, itself? :banghead:

I've read that some people have gotten free extended warranties, replacement pistons, or even replacement engines because of this. As far as I can tell, Gm's reaction to this problem is spotty, at best. Their standard line about the sound is "It's normal". What is so normal about an engine knocking? If we were talking about a 350 making this kind of noise at 15,000 miles, the dealer would replace it in a "Heartbeat".


I don't have any first hand experience with this problem. Nor do I claim to have any more knowledge than any of you. As I stated in another post, my truck, a 4.8 Silverado, has 80K miles on it, and it does NOT have a slap problem. It also doesn't consume oil between changes (which is also "normal" according to GM) like MOST vortec engines do. But, I'm watching a very close friend of 20 years deal with it. He's getting the run-around from the dealership and GM, and it upsets me to no end. They didn't hesitate to take his $28,000.00 when he bought the truck, but they sure do balk when he brings it back to get repaired! :angryfire
It's because of his experiences, and those of a fellow employee at work, that I'm considering a Toyota :eek:
If I wanted the fastest I'd buy a Lightning. Or, if I wanted the most powerful, I'd buy a diesel. I'm looking for dependibility and reliability. Unfortunately, In my opinion, GM is not offering that at the moment. For that matter, neither is Ford or Dodge.:disappoin

Do any of you really believe that GM designed these engines to make this sound, and consume oil at an accelerated rate, on purpose?REALLY? :screwy:

I guess noone here has ever experienced F Bods or Corvettes either????
Almost all the Gen III's have this noise. My truck started doing it at 10,000 miles. I have ran a blower on it for the last 3,000 miles, and it hasn't broke it, and I know of several other Gen III trucks that are over 100,000 miles, and make the same noise, and have since they were fairly new.
My ex GF's Subaru had a REALLY loud knock at startup, and less when it warmed up but still there, and the dealer service dept gave us a Copied paper explaining piston slap, short skirt pistons, etc. So it's not just GM that has the same deal.
It's not carbon, it's not injectors, it's not detonation. It's the short skirt pistons, and bore clearances required to operate the way they do.
Millions of F bods can't be wrong. :D

Do any of you really believe that GM designed these engines to make this sound, and consume oil at an accelerated rate, on purpose? REALLY? :screwy:

:rofl: :lol: :iceslolan :headshake :shakehead :spit: :lol2: :cwm27: :lol: :grinyes: :grinno: :disappoin :jump3: :wtf:

Sounds like we all have something in common. My 03 Silverado w/5.3L started "pinging" under light acceleration and pings a lot at highway speeds when you tip the throttle such as going up a slight grade. This started at 5,000 miles (currently 7k on OD). Likewise a heavy, horrible rotton egg smell started coming from the tailpipe. Has anyone else got this odor with their engine problems?

Dealership passed it off as bad gas but I dont put off-brand gas in 34 grand worth of truck. Tech 2 analysis revealed the ECM is controlling timing like it should. Fuel pressure regulator checks out ok. They replaced the O2 sensor in bank 1 and it still pings. Dealership says "trace" ping is normal but I dont consider this "trace" ping. My wife who is normally oblivious to anything mechanical even noticed the ping! That's bad.

Dealership also says exhaust odor is normal and proof the catalytic convertor is working. Sarcastically I told them GM must be worried then because every other Silverado I have ridden in (most friends have them) do not smell so their convertors must be defective. Dealership did not appreciate that.

I'm at a loss. Someone suggested the converter may be plugged but I figure something else had to be wrong to plug it right? Any help will be appreciated. Dealership running out of patience and so am I. Thanks.

Hay budd ,Im havig the same problum with my 2001 Silverado.
You cant here it when I first crank the truck BUT,after it sits idling for about 20 minutes it sounds like the valves and a rodd is coming apart.
The trucks only got 27000mls.,on it.the service manager at a chevy deiler told me that was normal for those 4.8 V8's with aluminom heads.
Let me tell you a little secret it isnt normal.

If you find a fix please e.mail me at
[email protected]

Well I don't know what to say or do.Ive heard things from bad plugs and coils,to short winged pistons.Im not douting none of this,becouse Ive not put the first rench on my truck except to change the oil.

All I know is that Ive been to two chevy dielers and Ive got the same runn-around.The same thing was said ,Its a normal thing for these
motors to sound like this becouse they have aluminom heads.


He told me that the all aluminom motor that there working on is going to be worse.

Me being an active dragracer,and building a couple of thumpers myself,and after 16 years of throwing renches,I know when someone is pulling the wool over my eyes.

People have asked me why dont I let it go,and fix the truck myself.;;Why should I,thats why we pay all that extra for these newer trucks with a warranty.

They even told me in (so many words ),that they wouldnt honer the warranty becouse I didnt buy it from a chevy dielership. I was reading an artickle a little while back where Chevy was manufacturing there motores in Mexico,NOT here in the United States.

All I know is Chevy has got a parts defection on these motores and becouse it has not become a health concern ,or a fire concern they wont do anything about there defective parts.

I honestly believe that for what I payed for my truck it shouldnt make a peep.

Tonny, I hear you, man, and I agree with you.

For months I've been asking a few questions of member of this board, and other boards, who consistantly defend GM when it comes to the quality of their engines.

I have no problem with the quality of the Chevy and GMC pick up trucks, themselves. I believe the quality of the vehicle is as good as anything else available, and better than most. It's the engines that seem to be the biggest problem. That and the standard line people get from the dealerships, "It's normal", or "There's nothing wrong that we can find", or "we checked it out, and it is within normal guidlines".
It's enough to make you want to scream!!!

When a working man (or woman) finally gets to the point where he can afford to drop $22,000 to $35,000 for a new pick up truck, he has every reason to expect that truck to be flawless, and free of defects. As far as I'm concerned, that is an assumption that I can no longer make when buying a new GM built truck. There will always be that haunting doubt in the back of my mind that the engine could develope a knock, or a ping, or whatever, and the dealership will not stand behind me. What's worse, It seems GM won't help, either! :banghead:

One of the questions I asked was this:
When you go to buy a new truck, and you pay $26,000.00 for it, how many defects are acceptable to you?

My answer is, of course, NONE! But that is not the answer that many Chevy loyalists gave!?!?!?! :shakehead

Some have defended GM by answering: "... well they make these trucks so fast that some defects are bound to happen" :eek7: What?!?!?!?

Another answer was, "...My truck doesn't make any sounds, maybe you should check you oil oncein a while..." Again, WHAT?!?!?!

The consensis seems to be that is only a few trucks are having this problem, and it's not my truck, well than maybe it's not really a problem.

Wheather you have a problem vehicle or not, the question is still the same:
Should GM take responsibility for defective engines, if the defect becomes evident while still under warranty?

My answer to this would be, YES!

I would add to that: Should they accept responsibility for engines that show these defects after the warranty expires, IF that engine type has a history of THAT PARTICULAR DEFECT?

My answer to this would be, Yes, because if the problem was known to exist, GM should have voluntarily recalled the defective engines and repaired or replaced them. In my opinion, leaving the buyer with a defective vehicle is just poor business practice.

I will be in the market for a new truck after the holidays. I will, of course, go to the Chevy and GMC dealers first, because I like GM's trucks. But, for the first time in a long time I'm going to be taking a serious look at the other guys, too. Not that I think their trucks are any better than Chevy's, (personally, I think as long as you buy a full size truck, it's difficult to get a bad one. I have no use for mini trucks, just too small for my 6'3" 235 lb frame) but because I believe the support from the dealership, and the manufacturer might be better. It certainly couldn't be any worse, in my opinion. :disappoin

Tonny, I hear you, man, and I agree with you.

For months I've been asking a few questions of member of this board, and other boards, who consistantly defend GM when it comes to the quality of their engines.

I have no problem with the quality of the Chevy and GMC pick up trucks, themselves. I believe the quality of the vehicle is as good as anything else available, and better than most. It's the engines that seem to be the biggest problem. That and the standard line people get from the dealerships, "It's normal", or "There's nothing wrong that we can find", or "we checked it out, and it is within normal guidlines".
It's enough to make you want to scream!!!

When a working man (or woman) finally gets to the point where he can afford to drop $22,000 to $35,000 for a new pick up truck, he has every reason to expect that truck to be flawless, and free of defects. As far as I'm concerned, that is an assumption that I can no longer make when buying a new GM built truck. There will always be that haunting doubt in the back of my mind that the engine could develope a knock, or a ping, or whatever, and the dealership will not stand behind me. What's worse, It seems GM won't help, either! :banghead:

One of the questions I asked was this:
When you go to buy a new truck, and you pay $26,000.00 for it, how many defects are acceptable to you?

My answer is, of course, NONE! But that is not the answer that many Chevy loyalists gave!?!?!?! :shakehead

Some have defended GM by answering: "... well they make these trucks so fast that some defects are bound to happen" :eek7: What?!?!?!?

Another answer was, "...My truck doesn't make any sounds, maybe you should check you oil oncein a while..." Again, WHAT?!?!?!

The consensis seems to be that is only a few trucks are having this problem, and it's not my truck, well than maybe it's not really a problem.

Wheather you have a problem vehicle or not, the question is still the same:
Should GM take responsibility for defective engines, if the defect becomes evident while still under warranty?

My answer to this would be, YES!

I would add to that: Should they accept responsibility for engines that show these defects after the warranty expires, IF that engine type has a history of THAT PARTICULAR DEFECT?

My answer to this would be, Yes, because if the problem was known to exist, GM should have voluntarily recalled the defective engines and repaired or replaced them. In my opinion, leaving the buyer with a defective vehicle is just poor business practice.

I will be in the market for a new truck after the holidays. I will, of course, go to the Chevy and GMC dealers first, because I like GM's trucks. But, for the first time in a long time I'm going to be taking a serious look at the other guys, too. Not that I think their trucks are any better than Chevy's, (personally, I think as long as you buy a full size truck, it's difficult to get a bad one. I have no use for mini trucks, just too small for my 6'3" 235 lb frame) but because I believe the support from the dealership, and the manufacturer might be better. It certainly couldn't be any worse, in my opinion. :disappoin






frankendart;;,and anyoneelse;;,
This is just my vew;For those who are dyhard Chevy fans theres one thing that we have to look at,

1,You eather did not get stuck with a truck that has this problum. OR.
2,You have a close inside,relationship with a Chevy Deilership. OR.
3,You have been one of those guys who buy there Chevy and deck it out with all the goodies,and its probably to late do anything about it now anyway.
OR.
4, Youre just like the rest of us ,you love youre Chevy,and you would rather have youre truck fixed wile its under warranty than trade the brand of truck.


You know every time I come out of a store I look over at my truck and I have to admitt that its the best d?mb looking truck in the parkinglot.,..BUT.,when I stop and think of what is rong with my engine all the nice feelings I had about my truck just whent down the toilet.



Lookes are not everything.,you have to look at dependability as well.Im expecting my wife to call me at work one day and tell me that the motor has let go and her and the kids are strandid somewhere.I guess we can all thank Chevy manufacturing for that.

I have gone many rounds with the dealership and GM over the knocking sound coming from my truck. I have a '00 4.8 L silverado. I was told by the dealership that it was a "Nuisance" noise that GM was aware of, but that there was no adverse affects to the longevity of the engine. HOGWASH. It doesn't take a rocket sceintist to tell you that if there is a knocking noise coming from your engine, it is because of something interferring with something else. That can't be good. Anyways I was interested to read the reply from the gentlemen earlier that said he heard it was affecting resale values. I went in last week to trade into another vehicle and they offered me $8000 for it. This is a '00 4.8L w/ 40K miles all power, not a scratch, burn, dent, ding, stepside bed, etc.. and I thought that was extremely low.. KBB qoutes trade-in @ 11,700 and private seller @ $13,800... interesting... did the dealership hear that knocking, and low-balled me on purpose because they don't want my truck??? if it is O.K. for us to have to deal with it, then it shoudln't affect trade-in right??

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....

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.

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.

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

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

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.

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? :banghead:

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? :banghead:


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

Right!!!!!

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.

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

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...

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