I went back to the dealership where I purchased the car and they agreed to cover half of the cost, it took about a week to replace and now (a month and a half later) I'm starting to hear a very faint chirping sound only at low rpms (700-2000rpms) I'm hoping it's just some squeaky sounds and not the harmonic balancer again otherwise I'm gonna go crazy

 

 

corvet786c Glad to see that your balancer is straight but mine is not. I want to keep this thread alive till I find a satisfactory solution to a very common problem among all LS engines. Dealerships seem to be telling customers that "wobble" is OK for some but straight on others? Its hard to justify 500 bucks (ATI) when my power train warranty is free. If anyone is going to find a solution to this it will be someone on here. So prepare to beat this horse till it turns to glue because there is still a problem.

 

You are one of the lucky few if they replaced the HB on an out-of-warranty car and only charged for half the book time. It's not difficult to change...just a pia...

As far as the current noise issue, get an automotive stethascope device and trace the problem. It may be something as simple as a worn out belt tensioner.

 

OK, so heres my story withl the harmonic balancer I had replaced last week (got my car back yesterday).

I have an 07 and after reading this thread a couple weeks ago, I was like I'll go look at mine and see if I have this problem and sure enough mine was wobbling. The dealer did everything under warranty. So they waited a few days for the part, installed it and it still had a slight wobble... They checked everything and all was well with the engine. They didn't know what do to next so we waited for a call from someone high up to see what to do next. They recieve the word from GM and they said that the pully wobble is an "Optical Illusion". I don't get it..I trust the mechanic that was working on the car and if he says everythings good, its good. (He owns a Z). So I got my car back, everything runs fine, the pulley has a slight wobble but I guess I'll live with it.

 

The "mechanics" at the dealership should know.... A slight wobble is normal, and the GM guy that called him is correct. But as I said, the mechanic should know this!!!

 

Having gone thru this on my 05 with a wobbling pulley causing belt chirping (took 6 weeks in 4 trips to dealer to resolve) and finally getting the balancer replaced, I can tell you that some pulleys run perfectly true as did the replacement. This "optical illusion" is bullsh*t put out by GM that doesn't want to admit that the part is problematic. When you look at the pulley with the engine running, if the pulley is running true the ribs of the pulley will look stationary. That's the optical illusion. Any movement of the ribs is an indication that there is wobble. This "optical illusion wobble" is just crap.

 

If your going to have your balancer changed you better put an ARP bolt in it. 40 dollars or less and you wont have to worry about it backing out and letting the pulley wear.

 

I fixed the "optical illusion" crap by placing my finger on the edge of the belt just after the balancer while it was running. Tap tap tap, no more "optical illusion"

.[/QUOTE=davidtcpa]The "mechanics" at the dealership should know.... A slight wobble is normal, and the GM guy that called him is correct. But as I said, the mechanic should know this!!!.[/QUOTE]
How do I measure the accepted "wobble"

 

Got a 2007 C6 with 13K miles. It's at the dealership today. Changed the Harmonic damper in Oct. 2010. Now once again they must change it. I've contacted GM Corporate and they say they will handle this. If they as so much come up with the optical illusion BS I'm gonna shove it right back up their butts. I'll keep you folks posted on the outcome but this time their messing with a someone with mechanical experience that is taking full advantage of the warranty.

OFF THE TOPIC: Also noticed a oily paint defect under my clear coat thats popping out in a few places in the car. That's also getting checked out and I'm waiting for an answer to that too.

 

The "optical illusion" part is that the face of the HD wobbles and the ribs do not. The third time the stealership replaced mine the face still moved but if you look down the edge of the belt from the pass side while the car is running it should be true. the crappy machining on the face will make the ribs look off. Look for a true belt thats as good as a stock ones getting. There is a whole lot of bad parts in new boxes.
ps. they also put the last one on the brake lathe to see the ribs before the install. If your having yours replaced with a stock one id ask to see it on a lathe first.

 

Your point on this is understood...However...the machining of the face being off would throw off the balance of this pulley also wouldn't it? They could add weights to counter the machining but when the pulley goes bad like it's doing for so much people how would they test that the outer ring of the pulley has or hasn't slipped from it's original position? This is where the chirping noise and or belt slippage noise comes from. The outer ring of the pulley being in a different position from when it was balanced would throw off the balance once again wouldn't it?

Adding to it, how do we know the crank itself doesn't have damage from all this wobble? I can feel the thudding vibration from my wobbling pulley when stationary and keeping the motor at higher rpm (2K - 4K). The engine mounts must eat most of that vibration, imagine how much the crank is getting.

My point is there should be no optical illusion or defect. I've only repaired harmonic balancers or dampers that were damaged or failed completely. (ex. 1996 Lexus GS300 with 3.0L inline 6 cyl. engine. The harmonic damper separated completely from the center hub. The rubber and glue that held it together completely failed. Luckily no damage to the surrounding parts, a corvette would be a different story...) I'll also need to add that months before while inspecting this pulley there was no signs of wobble, just the chirping noise and the sound of belt slippage when the ac was turned on.

Another example 2003 Chevy C2500 6.0L V8 No wobble at the pulley...

 

This was a common problem with the C5s. Numerous threads on the topic:

http://forums.corvetteforum.com/c5-t...-balancer.html

This was the inexpensive fix:

http://powerbondbalancers.carshopinc...6340/PB1117-SS

Definitely use an ARP bolt. In the case of the hi-po C5 applications, they keyed the balancer to the crank shaft snout. A search of the C5 forum will reveal that info.

 

Just goes to show how long Chevy got away with this. You buy a $40K and up Corvette and this is what you get. Most just swap it out to an underdrive but why should you if you paid the money to have a badazz car?

 

I'm not defending the sharty balancers by any means. Just clarifying what happened to me so others don't get the whole "optical illusion" scam dealers have been passing down for some time now. I wish they would just redesign the stupid things.

 

Specially if the problem has been around since the C5 era...

 

put in a new balancer bolt and loctite it

 

I just had mine replaced for the 4th time. now, 2 weeks later, it's wobbling and chirping AGAIN. FML The dealership has a 12 month, 12,000 mile warranty... I'm going up there tomorrow to raise hell. if they don't fix it for free. I am going to stand on the sidewalk with a sign that says, "Defective parts sold here".

 

One of the many benefits of "out-sourcing" parts production outside of the country. This particular problem has been going on for at least a decade. One wonders if the belt tensioner is leveraging too much torque on the borderline quality balancer.

 

Have them put the new one on a brake lathe or the like BEFORE they put it on your car. Have them let YOU approve the part first. You don't want the dealers "mechanics" under your car more than they have to be! Thats what I did. mine wobbles but the belt runs true and MARK THE OLD BOLT they tried to reuse mine but I marked it and called them out. Its a TTY bolt