Engine noise from light trucks has customers suing GM

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Engine noise from light trucks has customers suing GM
By AP

Owners of some of General Motors Corp.'s most expensive light trucks, including the GMC Yukon and Chevrolet Silverado, say the vehicles they paid more than $30,000 for may be worthless now because of loud, irritating knocking noises in their engines, lawyers tell the Free Press.

Thousands of vehicles, most from the 1999 to 2002 model years, may be affected, say the lawyers, who specialize in lemon law. They say GM is quietly buying back some of the vehicles.

Some experts say the knocking, caused by contact between the engine's pistons and cylinders, may be damaging the cars in the long run.

GM acknowledges the problem, which it said surfaced when it moved to a new family of engines, but says it does not affect engine performance and that it was corrected in later-model vehicles.

The problem is, there's no apparent fix for the earlier models, leaving buyers angry and worried. "I paid almost $35,000 for this truck. The truck is almost worthless," said Greg MacNeil, who purchased his 2001 Chevrolet Silverado two years ago. "In good conscience, I couldn't sell this truck to someone else."

When MacNeil bought the truck, he dreamed it would take him on long trips to northern Michigan.

But when his engine started knocking just two months after he bought it, he barely trusted his black pickup to take him 30 miles to work.

"I've been afraid to drive the truck up north," said MacNeil. "I only take the truck back and forth to work."

Ron Martiny of Oshkosh, Wis., had just returned from Florida in February 2002 when his Silverado's engine started knocking. His dealer told him the sound was normal. But a month ago, GM bought back his $40,000 truck, he said.

It's unclear exactly how many vehicles or how many kinds of GM vehicles have this noise, but customers and several lemon law lawyers say the problem occurs within months after customers drive them off dealer lots.

Lemon law lawyers say they occasionally get calls about engine knock with other automakers' vehicles, but they report an unusually high incidence of this kind of problem with GM vehicles.

"In the last year, this problem became really obvious," said Brian Parker, a Michigan lemon law attorney.

According to dealer service bulletins obtained by the Free Press, vehicles with the engine knock problem include 1999 through 2002 Chevy and GMC pickups and sport-utility models with 4.8-, 5.3- and 6.0-liter V8 engines.

The bulletins say that the noises are not detrimental to the vehicles, but experts say knocking is abnormal and can damage the engine.

GM officials say carbon and the amount of clearance between the piston and the cylinder wall are the primary causes of the knocking.

Usually, when the piston moves up and down in the cylinder, a component called the ring land, which is near the top of the piston, does not come in contact with the cylinder wall. But when carbon forms on the ring land over time, the ring land gets wider and begins to hit the wall. When the two come in contact, the driver will hear the knocking noise, said Chris Meagher, assistant chief engineer for GM's small block V8 engines.

Spacing is also an issue, because when there's too much room between the piston and the cylinder wall, a greater amount of rocking can occur and can cause more noise, experts say.

GM spokesman Tom Read said GM has addressed the issue by making design changes to the piston in some 2002 vehicles and all 2003 vehicles with the noise. GM has cut the amount of space between the piston and the cylinder so that the amount of rocking is reduced. The changes also keep the ring land from contacting the cylinder wall when carbon builds up, Meagher said.

Read said the knocking issue came about when GM started making a new family of truck engines in 1999. The company, however, vows that the knocking won't cause any damage to the engine because the carbon that has formed on the ring land isn't hard enough to damage the cylinder wall.

"Current analysis of 150,000 mile- and 300,000 mile-engines that have exhibited cold start noise show no significant wear," Read said.

And despite the controversy, GM's trucks got high marks in J.D. Power and Associates' 2003 reliability and dependability surveys. The Silverado, for instance, ranked second in initial quality in the study's full-size pickup category.

The noise, nevertheless, is irritating to consumers who have spent so much to purchase the vehicles.

"It's embarrassing," said MacNeil, who is suing GM. "If you accelerate, you can hear this vehicle 100 feet away."

There's also a question of durability.

While it remains unclear whether this knocking causes damage, lawyers and consumers say the piston's contact with the cylinder wall can't be good.

Knocking, for instance, has been known to cause damage to the piston, and in some cases it has resulted in premature engine wear.

Martiny, who bought his Silverado in February 2002, said he took his truck to the dealer after he noticed the knock and the service manager told him the sound was normal.

Then, in July of that year, the dealer talked to a GM customer assistance manager about the problem and later that month, Martiny got a letter from GM's Chevrolet division offering him a 100,000-mile warranty.

But Martiny said he didn't want the warranty because he planned to drive his vehicle far beyond 100,000 miles. He sought legal help in early 2003, and shortly after the automaker came with a $3,000 settlement. Martiny turned the money down.

According to Martiny and his attorney, Vince Megna, GM finally bought back the truck about a month ago. The company paid Martiny's $20,000 loan balance, plus another $20,000 and took care of his attorney fees.

Lemon law lawyers say this process is typical. GM usually offers consumers a 100,000-mile warranty to settle the matter. And when that's not good enough, the automaker offers consumers some sort of cash settlement for the noise, which can range anywhere from $2,000 to $5,000, according to consumers and lawyers involved in the cases.

When the cash doesn't resolve the matter, GM usually decides to buy the vehicle back, Megna said. Megna said the cases usually don't even make it to court.

"They know when these are filed, they aren't going to win these cases," said Megna, who practices law in Wisconsin.

Dan Powell, who lives near Orlando and owns a 2001 Yukon XL with an engine knock, was so incensed by the knocking that he created a Web site, www.pistonslap.com, that discusses the engine problem and seeks feedback from others with the issue. Powell is also suing to get his money back for the vehicle.

GM's Read said the company is working with angry consumers on a "case-by-case basis." Read wouldn't comment on any litigation, but said the knocking only affects "a small percentage of vehicles."

Read also wouldn't confirm or deny that the company is offering warranties, cash offers or buybacks for the vehicles.

What a consumer gets for the problem really depends on how hard they're willing to fight, lawyers say.

A lawsuit is generally the only way GM will buy the cars and trucks back, Megna added.

"GM has always bought the vehicle back, but only after being pushed," Megna said.

Clarence Ditlow, executive director for the Center for Auto Safety, said GM's stance on the issue is not surprising because repairing all those vehicles would cost millions of dollars. And if the defect doesn't cause a safety or emissions issue, it's tough to get a national recall.

The National Highway Traffic Safety Administration says it doesn't even track these sorts of problems because they aren't safety-related.

Consumers who have this problem should contact a lemon law attorney, Ditlow said.

"If you have a service bulletin, you're no longer arguing about whether (the vehicle) is defective," Ditlow said.

Meanwhile, consumers, many of whom are loyal GM customers, say they're disappointed that there isn't a repair for the problems.

"I would love to have it fixed if they have a fix," Powell said. "Except for the engine, it's a nice vehicle."
 
If I spent all that jack on a slapper I'd be on the list too web page Piston slap link .
Interesting story & post.
Something to remember when I go shopping for my next truck.
Here's the Pistonslap link again { the one you posted didnt work }
smile.gif


[ November 27, 2003, 01:06 PM: Message edited by: Scali62 ]
 
I question how many of the noisy "Vortec" GEN III engines actually have that sound caused by piston slap. I worked at a GM dealer up until the end of 2001 and we did have TSBs on these engines knocking. I recall watching a video with GM's solution of removing the spark plugs and soaking the pistons with combustion chamber cleaner to remove the carbon build up on the pistons. This is an effective way of removing carbon build up, which apparently this piston design is prone to.

Although I did see several 3.1/3.4 V6 engines with piston slap problems (nearly all that had this problem went away when warm), I don't recall ever seeing a GM truck with a slapping pistons. Our dealers biggest seller was fullsize trucks by a healthy margin. We also serviced many GM fleet owned trucks, which saw some extreme use/abuse.

Considering all this, and the fact that one angry customer can raise a big stink via the internet, I think way too many trucks with carbon build up are being considered pistons slappers. This is not to say that there aren't some pistons slapping trucks out there. Obviously the piston design and GM quality control are issues with these engines. However, I do think that this thing has been blown way out of proportion.

If I owned a GM truck of with one of the "piston slapping" Vortec V8s, I would follow GM's TSB procedure for cleaning carbon from the pistons. If this works, perhaps regualar additions a good fuel system cleaner, such as Neutra would prevent the build-up from returning.

[ November 27, 2003, 02:17 PM: Message edited by: Oldswagon ]
 
THe carbon issue is due to poor fuel management and head design. Why are they haveing carbon issues?? Fuel injected engines should never have varbon issue! GM is dumping to much gas into the cylinders to try to get HP figures up to be competitive. This puts alot of pressure on a marginal EGR system. That carbon has to go some place so pistons carbon up and so does the EGR system.

The piston slap issue is different then the carbon issue. If they added 30% more skirt area and moved the rings down a bit the problem would go away. If they went to a variable valve and lift system they could dumb less fuel in get the same power and have a braoder almost flat power band. The variable valve timeing would also act as a naatural EGR system. My 4 cylinder ULEV rated engine does not even have an EGR system! They could also aim the injector better. If you look at the LS6 they did a much better job with the injector aiming and the lower plenum floor is also better. I think these improvments could make this an excellent engine. These improvments would pay off alot more then their silly displacment on demand. First the engine has to function prperly before you start throwing gimicky gadetry at it!

They might also want to cosider letting robots measure and assemble their engines. THe above improvments only work if the parts are fitted properly. GM is spending money trying to improve it's quality but it is spending it's money very poorly and looking in all the wrong places. THey keep thinking that they can hire someone from the outside that will come in and fix theings. THey already know what needs doing but their internal political system will not allow improvments that need to bve made to happen. I equate what they are doing to be about as silly as looking for Betty Crocker Sussie Homemaker church going type of woemen in a Nevada whore house! I am not saying it can't happen only that it is unlikely!!

[ November 27, 2003, 02:40 PM: Message edited by: JohnBrowning ]
 
John, wouldn't they make more power and reduce carbon by leaning the motors out a bit? That, along with a more aggresive spark advance is what a Hypertech power programmer does
dunno.gif
 
quote:

Originally posted by JohnBrowning:

The piston slap issue is different then the carbon issue.


I realize that they are both very different issues. My point was, I think there are too many people with carbon build-up problems with these engines that are blaming piston slap for their engine noise. It seems with websites, such as that piston slap website, and so-called "internet forum experts", too many people are simply blaming any engine noise on piston slap. I don't understand how these "forum experts" can properly diagnose someone elses truck engine when they haven't actually heard the sound first hand, let alone acually looked under the hood. A experienced person may be able to say, "that sounds like it could be piston slap," but it seems everyone says "Your truck has got a case of GM piston slap."

And don't get me wrong, I am certainly not trying to defend these engines or GM in anyway. I like GM trucks, but I have never liked these new '99 and newer "Silverado" pickups or the new generation of V8's. I just don't want to have people get the wrong idea in there heads, especially if they have a relatively easy fix to get rid of their noise.

When I worked at the GM dealership, I was exposed to and drove a far higher number of these trucks and engines than the average person. As much as I don't like these trucks, I don't recall a single truck that I drove that wasn't extremely smooth and quiet. Perhaps, it has something to do with where the trucks are manufactured? IIRC, nearly all of our trucks were made in Oshawa, which is supposed to be one of, if not the best, GM plant for quality control.

In any case, I agree that GM has some serious design flaws with this engine that need to be addressed. I am not a fan of the variable displacement system that GM is proposing, but I am also not a fan of variable valve timing and lift systems. I don't understand why all the truck makers are in such a horsepower race to begin with. All these extra features are just more things to act up when the truck gets old. Trucks need to be reliable and cheap to fix when they get old. Do you think that a farmer or construction crew really needs that 300hp engine, only to have their trucks have a bunch of expensive electronic repairs when they get old?

Personally, my opinion is that GM's most reliable and durable truck engines were the 1987 -95 TBI gassers. These engines have enough power to do anything reasonable, they are tuned for low end torque unlike modern truck engines, and they are very durable if well looked after.
 
Regarding the cause of the noise being carbon build up on the piston rings- Auto-RX could be used to remove that carbon and restore quiet across Chevy Land! Problem solved by Auto-RX! Now if the noise is Piston Slap, then the next step is the proper oil to stop it. But do you select a light oil that will circulate quickly and lubricate the offending parts at start up OR do you select a heavier oil to provide a cushion between the metals. The real question is- does this piston slap indicate damage to the engine or just an irritating noise. GM is doing what many corp.s do. Deny any harmful damage so they won't have to shell out the mega buscks for many rebuilds or replacements of V8 engines.
 
quote:

Originally posted by Jim Spahr:
Regarding the cause of the noise being carbon build up on the piston rings- Auto-RX could be used to remove that carbon and restore quiet across Chevy Land! Problem solved by Auto-RX! Now if the noise is Piston Slap, then the next step is the proper oil to stop it. But do you select a light oil that will circulate quickly and lubricate the offending parts at start up OR do you select a heavier oil to provide a cushion between the metals. The real question is- does this piston slap indicate damage to the engine or just an irritating noise. GM is doing what many corp.s do. Deny any harmful damage so they won't have to shell out the mega buscks for many rebuilds or replacements of V8 engines.

And in short order, they are losing a large segment of their loyal customer base. What works in the short term finacially won't in the long run, unless they completely fix the problem, which it looks like they really aren't.
 
I hate to bring this up but the piston slap in Chevy V8 engines didn't start with the new 4.8, 5.3, 6.0 series truck engines and the 5.7 LS1 engines. It was a problem in the previous truck and car engines as well. I know the LT1 V8 had some TSB's issued related to piston noise. I have one in my 94 Impala SS.
 
As I stated in my above post, the 94-96 LT1 Chev V8's also had a problem with piston slap 'on cold start' only. Once warmed up this noise went away. My question after reading the web site regarding the Chev V8's 4.8, 5.3, 6.0 and so on: Do they have a constant piston slap noise- warm or cold- or is it on 'cold start only?'. It would seem it is a constant noise from what I read. That would indicate a much more serious problem.
 
The 5.7L vortec in my 98 chevy has startup tapping/knocking, whatever you want to call it. Its alot quieter with the Chevron but it may come back with more miles on the oil. Mine started at about 34,000 miles and this is on a truck that has been meticulously maintained.

The bottom line is that it really shouldn't matter what it causing the noise. Consumers don't want to spend 30,000+ dollars on a vehicle that makes noises on startup. I think its a design flaw. I've had many chevy V-8 engines in the past that never had startup noise unless it had a mechanical problem. The 396 big block in my 70 Monte Carlo doesn't have this type of noise and it didn't have it before it was rebuilt either. Neither did the couple of 350's and the 400 sb that were in it before.

Part of the problem is that alot of these people that get a vehicle bought back or get rid of one, turn around and buy the exact same thing in the hopes that the next one won't have the problem. What you have just done is reward GM once again by spending your money for their product. GM has no incentive to fix this because they still sell every truck they make and until people vote with their wallet and buy elsewhere, I don't think GM is going to do a thing.

Wayne
 
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