I recently bought a '02 'Vert 6-speed with 4,600 miles. I noticed a slight ticking sound so on the test drive I went by the Chevy dealer just to ask. The service writer said it's "normal". Since it was in such good shape and was exactly what I had been looking for and drove perfect, I bought the car since it still had one year left on the warranty.
Now the sound is louder but only starts after one minute following a cold start and continues, it's quiet on initial start-up.
Before going back to the dealership I was looking for advice or opinions.
I've listened to several C5's here locally and they dont have this sound.
I can't tell which bank it's coming from but it's not a deep noise.
Thanks,
Dan

 

I have a 98 and mine does exactly the same thing , although after 5 min it is completely quiet.. GM says its harmless and they call it piston slap. They will extend your warranty if you complain about it, but seems ok to me. You will get used to it.

 

It's normal. It's an LS1 thing. As IGO said, it is called "Piston Slap" and it is caused by non-exact cylinder-to-wall clearances. It is even worse in the iron-block 350's used in Chevy trucks.

The only cure is a complete engine rebuild. You'll just about need a lawyer to get a dealer to do that under warranty too. You're better off pushing for the extended warranty.

But as I said, it's nothing. It won't cause any problems or abnormal wear.

 

Yep...it happened on my '03 6-spd Coup'e. My '04 is quiet as a mouse so far with 4000 miles.

 

These cars can make many noises, from a variety of sources. To diagnose for piston slap:

1. Have dealer attach a Tech II (or similar device) to the computer data port.
2. Cut fuel to each cylinder, one by one.
3. If the sound changes/goes away, you've found the bad cylinder(s), and verified piston slap.

If the sound only occurs at cold start up, and the car is not using oil, then the only problem may be enjoyment of the car/resale value.

If the sound occurs when the engine is warm, and continues all the time:

1. Carefully check for oil consumption. A rocking piston may not seal very well against the cylinder wall, allowing oil to blow by.
2. Use a borescope to examine the cylinder wall of the bad cylinder(s) to check for scoring. If scoring is present, oil consumption may occur.
3. Check compression in the bad cylinder(s).
4. Oil consumption can be a problem if carbon build up occurs, which can cause detonation, reduced fuel economy (incomplete combustion), more carbon build up, etc. A temporary fix is a 'decarb (solvent)' procedure (after which the oil must be changed).

Piston slap is not a normal condition, and can occur on just about any car, regardless of make: it can occur any time tolerances are out of spec during manufacture, or at higher mileage, when the engine is worn out.

If the problem gets worse, an extended warranty may not cover the repairs, as piston slap at higher mileage is also due to an engine wearing out.

If the noise only occurs at cold start up and goes away, and the engine does not use oil, then it's probably not worth the hassle to pursue a repair (as others have noted). If the noise is there all of the time and/or the engine starts to use oil, it may be worth the effort to push for a repair before the original 3YR/36K warranty expires.

Type 'piston slap' into www.google.com for more information.

 

Thanks a bunch folks....that gives me something to go on!
Dan

 

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I just went through this entire process with GMC. 02 coupe with 22K miles. I had the noise since it was new and was told by the dealer it was not going to hurt anything. I took it to another dealer and they were great. Work with the factory rep. got all new pistons, rings, etc . In addition GMC Cust. Services provided me with an additional 48 months, 72K miles , no deductible , warranty on the entire drive train, fuel systems.

The noise is GONE and it runs great. In addition the slap noise had grown into a little oil problem which is now also gone....

Get it fixed and push for the extended warranty. They will do both so don't let them BS you....

 

Terry, I'm glad you were able to work through this and get it fixed. You are one of the lucky ones, and the dealership you worked with is an outstanding one for supporting its customers like that. Unfortunately this is not the most frequent scenario, and 9/10 dealerships are not willing to perform such work. Consider yourself very, very lucky. I wish my dealerships were that honest.

Thanks for the encouragement. Maybe if the word gets out then it will make a difference. Or at least maybe the LS2 will not have not have such problems.

Cheers,

 

Your choice of oil and filter can have an effect on engine noise. What are you running?

 

I'd be glad to share any and all information I have about my dealings with the dealorship and GM Customer Assitance...I have a case number that could be referred to.

Terry

 

I run the recommended oil and filter straight from the factory. I have never ventured outside of what it came straight from the factory with. Mobil 1 5-30w syn. with factory GM filter...never had a problem.

Terry

 

I've tried the GM factory filter, Mobil 1 filter and the K&N filter with no difference in noise. I've only used Mobil 1 5w/30 oil.
I'm installing another GM filter before I take it in, just in case.

Cool Terry....
Thanks for the offer, I may be taking you up on it!
Dan

 

I just called GM 1-800-222-1020 (Chevy).

The rep told me that there were no TSB's about this problem on my 02 Corvette, and they are hearing more and more about the problem. The rep is checking on extending my warranty and will call me tomorrow after she gets approval or disapproval. She also said they think it's caused by carbon build-up on the rings and pistons.

The warranty extension does not fix the problem but at least it's something. In the meantime I'm inquiring about joining the class action suit of Green & Jigarjian LLP (Monica S. Herman at (415) 477-6700 or by email: gj@classcounsel.com

 

There was a GM PI document regarding replacing all the pistons for this condition. The last dealer I interviewed stated that the new 'special' pistons were not available. After interviewing many experts, the correct method to repair is to rebuild the short block (machine shop, etc.). This is what Cool Terry had done with his engine, and it was successfully repaired.

Carbon knock is caused by a significant amount of carbon build up causing the piston to hit the head (from the carbon). My experience with the LS1/LS6 has been that significant carbon build up occurs when there is oil consumption (causing incomplete combustion, perhaps KR and richened mixture to stop knocking, resulting in more carbon build up, etc.). Thus, if the oil consumption is via the rings and/or is a result of piston slap cylinder wall scoring (AOT intake/PCV), a rebuild may still be required.

 

Update......

Took my car to the dealership about my clicking noise. The Shop Foreman and Tech agreed that the sound became noticable after one minute of idle time following cold start-up.
They also stated that it's "normal" for the LS1's to tick and I disagreed and asked them to go with me and start all four new 'Vettes and three used C5's on their lot....They declined and said nothing could be done now. I guess they want to wait until October until my warranty expires and get full price for a re-build....It's not gonna happen!

Round 2 starts tomorrow with GM's Customer Service.
Dan

 

Dan:

I have a habit of choosing to own cars that end up with vast numbers of warranty claims, so I have been around the block a number of times. If you are an informed consumer, AND you are polite, AND you admit that neither the dealer nor the warranty rep are personally responsible for your car's troubles, you should be fine.

This may sound like Pollyanna, I suppose, but I got Mercury to replace the engine on my Merkur when it had 99, 400 miles on it (I bought a 100k warranty) because a leakdown test showed two low cylinders. At first the rep refused. I asked the manager to get a service manual. We looked up the leakdown specs. My car didn't meet the specs. They gave me an ugly as Town Car for a week and a new motor.

It can be done. Good luck! Smile, bring coffee, ask them how their kids are doing, and make sure they give you what you want. Everybody wants to be treated with respect. Because this usually doesn't happen if you're a Service Rep, most Service Reps are primed and ready to burn the first person that treats them disrespectfully.

One other thing: check your warranty carefully; call GM if you have to. You want to make sure that you have a repair order or some other "legal" document that shows that you have a problem. I often will send, or carry, a letter indicating all the details of the problem. If you're not satisfied with their response (and there is a repair order), write on the order a short description of what the problem was and why you are not happy. Make sure you include what the dealer gave you as a reason. Then follow up with a polite letter to the service manager. Remember, if the Service Rep sees you being a person who REALLY wants to be a loyal Corvette owner, you are in a much better position to get what you want.

Finally, many states (and I think GM, too) require a Manufacturer to extend the warranty to make up for any days the car was out of service due to warranty repairs. Many manufacturers calculate the "end of the warranty period" as the end of the month, not the actual date, e.g. if your warranty runs out on October 6, 2004, they may actually allow warranty claims until October 31.

Regards,
GP

 

Latest update......
GM has extended my engine warranty to a total of 7 years or 100,000 miles. They would not tear down my engine to find the noise, they stated that it was common and no problems have came up because of the noise.
I'm content with 4+ years and another 90,000 miles. It may not be a re-build but it does restore some faith in Chevrolet.
Thanks again to all who responded and a special thanks to Cool Terry for his help.
Dan

 

Now call around until you find a dealer who will tear your engine down and fix the noise!

 

But then that would probably void his new warranty.

 

following Terry's adventure I would say that his dealer has set a presidence in being able to eliminate the problem with a full teardown and rebuild,I think we should all press the issue,Terry has stated that he has the case number we can refer to.

John