Hello,
I'm experiencing a slight knocking noise, during warm-up. After a couple of minutes, it goes away. Is this a characteristic of cold morning starts with Synthetic oil, or a characteristic of Z06 the valve train?

Also, wher can I go (for info) to view all of the differences and spec's of the Z06.

Thanks

 

I too have this issue. Dealer said it was "short skirt pistons". I dont buy it. let me know what all ou find out...

 

I believe this is called, "piston-slap". Warranty issue. Also a known issue with some Z06s!
-Bill. :(

btw my 02 z06 had this issue. i traded it in for a 2003 Z.

 

All of the new generation small blocks do this. The pistons have short skirts, I was told it is a "gas mileage" thing-motors are set up real loose. Just make sure it is documented, from what I know it won't hurt anything. Just loud and annoying at times. My ex-wife and I sued GM over a sierra pickup that did it and they paid it off and lawyer's fees. They know about it, but have no solve for it. They tried teflon coated pistons etc but to no avail. :bs


[Modified by camarocasanova, 10:07 PM 10/3/2003]

 

I've been told that if you raise hell with Chevrolet about this issue they may offer you two remedy choices:

1) New motor with original warranty, or

2) 100,000 mile warranty on the original engine (engine only)

 

Well in which direction do I complain? I am not having much luck getting anytign done aboutit.

 

[QUOTE]I've been told that if you raise hell with Chevrolet about this issue they may offer you two remedy choices:
1) New motor with original warranty, or

2) 100,000 mile warranty on the original engine (engine only)
[quote]

The first step is to get the noise documented in writing. Get at least four service orders from at least two dealers documenting your attempts to get the noise diagnosed and repaired. It's OK if they claim there's no noise or it's normal, etc., just get your attempts in writing (no matter what, don't leave without your paperwork!). Call the GM 800 number and tell them you want the car fixed. If you don't make any progress (they'll likely tell you to take it to another dealer), write a certified letter to the dealership owner(s) and management asking for a GM rep to examine your car.

Ask to have the car repaired. They may try to persuade you to take an extended warranty (limited dealer experience with Z06, car could get damaged etc.). However, if you have four prior attempts to address this issue in writing, if they botch the fifth attempt (actually trying to repair the defect), then you'll have a very strong case for a Lemon Law claim.

In terms of business and profit, I understand a manufacturer's motivation to save money, but it's sad that consumers have to jump through rings of fire and deception to get their cars repaired.

Sometimes dealing with the manufacturer is like the Monty Python skit with the dead (defective!) parrot at the pet shop (Manufacturer):


A customer enters a pet shop.

Mr. Praline: 'Ello, I wish to register a complaint. (The owner does not respond.)

Mr. Praline: 'Ello, Miss?

Owner: What do you mean "miss"?

Mr. Praline: I'm sorry, I have a cold. I wish to make a complaint! Owner: We're closin' for lunch.

Mr. Praline: Never mind that, my lad. I wish to complain about this parrot what I purchased not half an hour ago from this very boutique.

Owner: Oh yes, the, uh, the Norwegian Blue...What's,uh...What's wrong with it?

Mr. Praline: I'll tell you what's wrong with it, my lad. 'E's dead, that's what's wrong with it!

Owner: No, no, 'e's uh,...he's resting.

Mr. Praline: Look, matey, I know a dead parrot when I see one, and I'm looking at one right now.

Owner: No no he's not dead, he's, he's restin'! Remarkable bird, the Norwegian Blue, idn'it, ay? Beautiful plumage!

Mr. Praline: The plumage don't enter into it. It's stone dead.

Owner: Nononono, no, no! 'E's resting!

Mr. Praline: All right then, if he's restin', I'll wake him up! (shouting at the cage) 'Ello, Mister Polly Parrot! I've got a lovely fresh cuttle fish for you if you show... (owner hits the cage)

Owner: There, he moved!

Mr. Praline: No, he didn't, that was you hitting the cage!

Owner: I never!!

Mr. Praline: Yes, you did!

Owner: I never, never did anything...

Mr. Praline: (yelling and hitting the cage repeatedly) 'ELLO POLLY!!!!! Testing! Testing! Testing! Testing! This is your nine o'clock alarm call! (Takes parrot out of the cage and thumps its head on the counter. Throws it up in the air and watches it plummet to the floor.)

Mr. Praline: Now that's what I call a dead parrot. Owner: No, no.....No, 'e's stunned!

Mr. Praline: STUNNED?!?

Owner: Yeah! You stunned him, just as he was wakin' up! Norwegian Blues stun easily, major.

Mr. Praline: Um...now look...now look, mate, I've definitely 'ad enough of this. That parrot is definitely deceased, and when I purchased it not 'alf an hour ago, you assured me that its total lack of movement was due to it bein' tired and shagged out following a prolonged squawk.

Owner: Well, he's...he's, ah...probably pining for the fjords.

Mr. Praline: PININ' for the FJORDS?!?!?!? What kind of talk is that?, look, why did he fall flat on his back the moment I got 'im home?

Owner: The Norwegian Blue prefers keepin' on it's back! Remarkable bird, id'nit, squire? Lovely plumage!

Mr. Praline: Look, I took the liberty of examining that parrot when I got it home, and I discovered the only reason that it had been sitting on its perch in the first place was that it had been NAILED there. (pause)

Owner: Well, o'course it was nailed there! If I hadn't nailed that bird down, it would have nuzzled up to those bars, bent 'em apart with its beak, and VOOM! Feeweeweewee!

Mr. Praline: "VOOM"?!? Mate, this bird wouldn't "voom" if you put four million volts through it! 'E's bleedin' demised!

Owner: No no! 'E's pining!

Mr. Praline: 'E's not pinin'! 'E's passed on! This parrot is no more! He has ceased to be! 'E's expired and gone to meet 'is maker! 'E's a stiff! Bereft of life, 'e rests in peace! If you hadn't nailed 'im to the perch 'e'd be pushing up the daisies! 'Is metabolic processes are now 'istory! 'E's off the twig! 'E's kicked the bucket, 'e's shuffled off 'is mortal coil, run down the curtain and joined the bleedin' choir invisibile!! THIS IS AN EX-PARROT!! (pause)

Owner: Well, I'd better replace it, then. (he takes a quick peek behind the counter) Sorry squire, I've had a look 'round the back of the shop, and uh, we're right out of parrots.

Mr. Praline: I see. I see, I get the picture.

Owner: I got a slug. (pause)

Mr. Praline: (sweet as sugar) Pray, does it talk?

Owner: Nnnnot really.

Mr. Praline: WELL IT'S HARDLY A BLOODY REPLACEMENT, IS IT?!!???!!?

Owner: Look, if you go to my brother's pet shop in Bolton, he'll replace the parrot for you.

Mr. Praline: Bolton, eh? Very well. (The customer leaves.)

(The customer enters the same pet shop. The owner is putting on a false moustache.) Mr. Praline: This is Bolton, is it?

Owner: (with a fake mustache) No, it's Ipswitch.

Mr. Praline: (looking at the camera) That's inter-city rail for you. (Mr Praine goes to the train station. He addresses a man standing behind a desk marked "Complaints".)

Mr. Praline: I wish to complain, British-Railways Person.

Attendant: I DON'T HAVE TO DO THIS JOB, YOU KNOW!!!

Mr. Praline: I beg your pardon...?

Attendant: I'm a qualified brain surgeon! I only do this job because I like being my own boss!

Mr. Praline: Excuse me, this is irrelevant, isn't it?

Attendant: Yeah, well it's not easy to pad these python files out to 150 lines, you know.

Mr. Praline: Well, I wish to complain. I got on the Bolton train and found myself deposited here in Ipswitch.

Attendant: No, this is Bolton.

Mr. Praline: (to the camera) The pet shop man's brother was lying!!

Attendant: Can't blame British Rail for that.

Mr. Praline: In that case, I shall return to the pet shop! He does.

Mr. Praline: I understand this IS Bolton.

Owner: (still with the fake mustache) Yes?

Mr. Praline: You told me it was Ipswitch!

Owner: ...It was a pun.

Mr. Praline: (pause) A PUN?!?

Owner: No, no...not a pun...What's that thing that spells the same backwards as forwards?

Mr. Praline: (Long pause) A palindrome...?

Owner: Yeah, that's it!

Mr. Praline: It's not a palindrome! The palindrome of "Bolton" would be "Notlob"!! It don't work!!

Owner: Well, what do you want?

Mr. Praline: I'm not prepared to pursue my line of inquiry any longer as I think this is getting too silly!

 

FYI: Auto manufacturers spend MILLIONS of engineering dollars to avoid piston slap issues. Here's an engineering simulation paper:
http://www.mscsoftware.com/support/l...8/euc98_19.pdf

It's a build variance defect: too much piston to cylinder wall clearance (and/or net geometry variance) and you can get two problems:

1. Piston slap noise and possibly cylinder wall damage.
2. Oil consumption.

Solution: Improve quality control at manufacture and/or change design to improve probability of a low occurance of defects.

Solution for owners of defective engines: replace engine with a non-defective unit. This has the highest chance of success: many local dealers are not qualified to make internal Z06 engine repairs (I've researched this first hand: the GM 800 number people will tell you all dealers are equally qualified: if you interview dealers in your area you'll find this is not true).

If your engine makes a knocking noise, you are entitled to a repair. You are not unreasonble or too picky. Would you have purchased the car in the first place if they disclosed that the engine knocked (regardless of how loud it was)?

Here's a recent case ruling involving an auto manufacturer and piston slap:

From http://myfloridalegal.com/AprJun01.PDF .

 

Here's a website dedicated to dealing with the piston slap issue: http://www.pistonslap.com (perhaps a bit over the top sometimes, but has good links and info).

Here's a Z06 engine noise (this is fully warmed up, it never goes away): http://www.brightland.com/cf/video/z06noise.wmv . It sounds very similar to the piston slap noise on the pistonslap.com website. The manufacturer claims it's a wrist pin... This engine burns around 2 quarts of oil in 3000 miles.


[Modified by johnC5, 12:45 PM 10/8/2003]

 

I have the same exact thing with my Z06. At first I thought it was a lifter, but I guess it is a form of piston slap. It only knocks/slaps, clacks during warm-up, then goes away completely. Specifically, it won't clack immediately after startup, but after about 30-60 seconds after the engine has started, it will begin clacking, and it will continue for the next 2-3 minutes of driving, until the oil temp is over 110F, then fades away, and the noise is completely gone when fully warmed up. The noise also disappears when the RPM's are above 2,000. It's loudest at about 1,500.

If I restart the car while it's warmed up, it will clack right away for the first 30-60 seconds, then goes away.

I'm not going to worry about it. The noise hasn't changed in 9k miles, the car runs great and strong, and oil consumption isn't bad at 1 quart every 3k miles with hard driving. If the engine breaks in the next 2 years, I'll call up GM and tell 'em to fix it (warranty is a good thing). If it breaks after that, then it's the perfect excuse for the 427 I've always wanted. :D