After many months and dealer visits, the engine noise was solved by a GM rep in about 15 minutes using a Tech 2.

Here again are the videos:
http://www.brightland.com/cf/video/Z06Noise.wmv (Large: 1.1MB) http://www.brightland.com/cf/video/Z06Noise_small.wmv (Small: 732KB)

The answer is:

Cylinder number 8, wrist pin (manufacturing defect).

The problem was isolated by using the Tech 2 to turn off cylinders, one-by-one until the noise went away.

In order to help other Corvette owners for the future, it might be useful to archive these videos and the solution in order to save other owners time and grief.

Thanks to everyone who helped verify that the noise was not normal and for all the suggestions. I was able to get a GM rep to examine the car by emailing the owner of the dealership. Essentially, I followed the instructions in the warranty section of the owner's manual.

 

Hi John,
Couldn't run the video. But what dealer found the problem? What did it sound like?

MikeV

 

Congrats on the find! :cheers:


[Modified by Scott-2002-Z06, 2:04 PM 3/3/2003]

 

I am thrilled for you they know what it is - I only knew it wasn't normal, no matter what the dealer said. I am blessed with an excellent dealer and top line Vette mechanics at that dealership (Tom Jumper) here in Atlanta, and I feel bad for those who don;t!

Les

 

They replaced the wrist pin in 15 minutes? The wrist pin hold the piston to the connecting rod. I would think that the motor has to come out to fix that.

 

:iagree: That's exactly what I thought... :chevy

 

I believe he meant it was DIAGNOSED in 15 minutes...

:cheers:

 

The GM rep identified the problem in about 15 minutes using the Tech 2 as described above. They have offered to replace just the piston and connecting rod assembly (which includes the wrist pin). They quoted two days to repair. This problem has been present since day one (now at ~7200 miles). Will their recommended repair be sufficient?

 

It's a ticking/knocking like noise that's loudest from underneath the car. It could be confused with valve train or injector noise. The key elements are the sound is deep and easier to hear with the hood closed. Using a Tech 2 or similar device to turn off the spark on each cylinder (to eliminate combustion-to-piston load) allowed the problem to be isolated.

 

It's not fixed yet: the cause of the problem has been solved. The fix requires pulling the cylinder head and dropping the oil pan (after removing the frontend assembly). Apparently a major operation.

 

Maybe major, but if your dealer has done some re-rings as required on the oil consuming cars (as was done to mine), then they will easily be able to do this for you as it will involve the same tear down of parts, and better yet it's only one piston instead of all 8! :seeya

 

I WOULD NOT settle for anything less than a new crate motor! :bs

 

Make sure you see the block. Anytime a wrist pin acts up you risk the bore. I know you can't ask for a new engine but I sure would want one. Are they floating pins or pressed on a LS6?

 

I'm not so sure that they can identify the noise as a wristpin related noise just because the noise stopped when combustion for the cylinder was cut. I really do not buy that. The short block probably needs to be completely inspected. It sounds like they are happy to help you which is great. I hope it all works out for you.

This repair requires more than that. The entire motor should come out for sure. At least one rod/piston assembly has to come out. Removing the crank and bearings and inspecting the bearings & journals would also be wise.


[Modified by rbartick, 11:03 PM 2/28/2003]

 

You can accomplish this by pulling the spark plug wires too, one-by-one....just a suggestion for those without a tech 2 :cheers:

 

If you are going to pull a plug wire and leave it running for more than a few seconds then also pulling the corresponding injector wire to prevent fuel wash would probably be a good idea.

 

Whatever it is can not possibly be normal engine noise. Mfg defect? Did it always make this noise? I get a light ticking from my own setup, nothing near the noise your engine is making. Good luck w/repairs.

 

Just to recap this saga: we now know the following:
1)The 'normal' noise being emitted from your engine was NOT normal from day one.Either the dealership mechanics and service managers u encountered were lying through their teeth or they're incompetent; which one is it? (I don't want to hear any excuses like"it's such a rare problem that ONLY a GM rep could diagnose it"-mechanics been diagnosing a purely mechanical problem like this since 1923).
2) The key to getting your car diagnosed (remember ,it hasn't been fixed yet)was contacting the dealership OWNER directly.This means that NO ONE @ the dealership helped u,why was that? (see #1)
The dealership owner would have been contacted upon my first visit (not my 10th) after the general mgr. called to inform him that a customer was escorted out by police because he refused to be lied to or that a customer had parked a lemon draped car out front, demanding his $50k 'diesel' corvette fixed.
3) How much is your time worth,not to mention the anxiety in plotting your next futile appeal to dealership mgmt? Call it 'bullying' or what u will,but my warrantee would have been honored from the beginning-"normal sound" my A!
4) The warrantee was not a gift given to u, IT WAS PART OF THE PRICE OF THE CAR( probably $3-4K worth) Did I forget to mention u paid for it?
5) The same mechanics who didn't bother to expend any effort to diagnose the problem; who in fact told u to "come back when it gets worse" are the same people u will entrust to tear the engine in your $50k corvette apart and put back together? (Now I know what some will say,that using my approach would result in them doing an inferior repair to my engine because I was less than pleasant; this would be true if they had me pegged as a sucker,but trust me they would do an impeccable job in order to never see me again. By the way the owner doesn't want to hear the service mgr.'s excuses when I'm back for a new engine!)
Good luck w/ your engine and stand up for yourself man.
;) :smash: :smash:

 

Inspect the entire engine to find the exact problem, or to look for additional wear/damage?

 

They can pull the suspect rod and piston without removing the motor to inspect for damage IMO. RB knows his stuff though, so not sure what he is suggesting, I am sure he will reply. For sure I would want them to do a thorough examination of the cylinder itself to be sure the wrist pin "slop" did not cause excessive wear etc. They will know what they are dealing with as soon as the drop the pan and remove the piston - again IMO.

Good Luck!

Les