How much Harmonic Balancer Wobble is "normal"? In other words, should there be any visual movement?

I had an engine squeak and thought maybe it was the harmonic balancer. First dealer didn't hear it. I went to another dealer yesterday with a really good Corvette tech, and he replaced the alternator. Sounds better today, I didn't hear my birds this morning.

But, my Harmonic Balancer bounces up and down, and the tensioner jerks and moves a similar amount. Looks like a nervous person bouncing their knee up and down. I've asked the shops to check it, but they haven't noted a problem.

When I look at the LS2 in my TBSS, the tensioner is steady, and I don't see the balancer moving. Does everybody have visual movement or bounce in their balancer??

 

It's obvious something is F'd up if you can see the run out.

 

Its not going to get better on its own and can cause catastrophic damage when it goes. Nip it in the bud.

 

Obviously, any wobble isn't ideal but a small amount of wobble can be within 'normal' operating parameters. I had a tensioner break at the track...it split in two like a clamshell. After putting a new tensioner on I noticed a slight wobble with the crank-pulley. It didn't seem loose but I didn't run the car anymore that weekend. I had a mechanic check it out and he thought the wobble was "acceptable." I was going to buy an aftermarket pulley but the he suggested to run the car and see what happens. Some time later (strangely at a Buick dealership) I asked the mechanic what he thought....he said the GM balancers aren't the greatest and he pointed out the center area of the pulley spun true but the 'deviation' was evident at the outer edge. I've been running the car hard for well over a year now and I haven't had any further problems.

If your mechanic assures you the pulley is on tight and your belts aren't fraying I was inclined to say drive the car and see what happens (why spend a grand if you don't have to?). However, your wobble sounds considerably worse than mine. My pulley had a very slight side-to-side wobble...not the almost violent up and down bouncing your's seems to have. I'd get a second opinion and I lean towards replacing it (with a quality aftermarket pulley). Let us know what happens and good luck.

 

What year/ production date is your Vette?
Does it fall within the recall range?
Has the HB already been replaced?
Extended warranty availiable?

Is it at all possible for you personally to get a socket on that bolt (without rack removal) to check tightness? I am not sure.

Seems like you are doing a good investigation...find some more LS2s and compare.

I be inclined to fix it before it "explodes" as it might damage the hood. Yes, expensive preventative maintenance ala Ferrari.

 

It's a 2007. Only 7,900 miles (my fault). So, not a recall item as the 05's had. I do have the GMPP warranty until 2013, so the alternator replacement yesterday was no cost. I'll keep an eye on it, but wasn't sure if any movement is typical. Not used to seeing them move. Mine is not violent to the point I think it is going to throw a belt, etc. Thanks folks.

 

Essentially the criteria that GM is using is that if the wobble doesn't cause the belt to chirp or be thrown off then it's acceptable.

 

There is difference between wobble and out-of-round. With wobble the pulley is moving back and forth or front to back if looking down on the engine but the tensioner probably won't be moving much if at all. However, if the crank pulley is out of round because the insulator between it and the hub got bunched up at one point or is missing then an out-of-round condition will exist and the tensioner will be going crazy.

If you are asking them to locate a wobble problem they may not see a wobble and simply choose to ignore the out-of-round issue.

Either way it should be corrected.

 

You know, that is an excellent point. The Wobble description may not be accurate for me now that you mention it. I can see where a wobble would be a loose pulley, and goes in and out like the Griswald Family Vacation station wagon wheels. That is not what I see with mine. My balancer/dampner kind of bounces like a tire out of balance, or out of round like you mentioned. Thank you.

 

Mine has some in & out wobble and belt chirp when cold. Maybe an 1/8 to 1/4" wobble. Since my extended warranty will expire in March, and car will be stored until then, I have opted to get it replaced. It will be done next week.

 

Seems like a very little wobble is "normal".

I have had 2 balancers replaced in 39K miles and when I pick up the car each time it still has a very small wobble.

 

GM has serious problems with anything to do with rubber technology and/or manufacturing quality, be it tires, harmonic balancers, crankcase seals, waterpump seals, etc., etc. Such intrinsic problems can usually be traced to incompetance or corruption in purchasing and/or management itself.

 

Obvisiously some conspiricy here.

 

I am new to the corvette community and recently purchased a 2006 vette and had been shopping for about 5 months. I noticed that 4 of the 5 2007 model year cars that I drove had some sort of wobble in the dampener. Some severe and some in the beginning stages. Upon noticing this on my first vette test drive , I researched it and found it to be a significant problem on corvette forums . The sad truth is the 2 GM stealerships that are local told me it was normal and acceptable. In my opinion that GM is ignoring the issue. I have owned lots of cars and never noticed an outright engineering failure in the crank pulley "wobbling" . From my observation it seems that the 2007 model year suffers this more often than other years. My 2006 has 9k and no signs of any deviation in the crank pulley/ balancer.

I stumbled upon this problem on my first corvette test drive and thought it was belt noise only until I popped the hood and looked at the dreaded wobble.....

 

So I would guess this is normal amount of run out and out of round ?
http://www.youtube.com/watch?v=XrYo7GzNKHE

 

I'd like to reduce this to numbers if we can. Since the only way to measure runout is with a dial indicator (that I know of), and since that is impractical for this application, would there be some use in measuring the travel of the boss on the serpentine belt tensioner? My crank pully wobble is moderate (but that will mean different things to different people) and my tensioner moves 1/8 to 3/16 (but I have not yet put a steel rule down on it). Might another possible measurement be the paper-thickness tuft of rubber (the vibration isolator) sticking out between inner & outer parts? Mine feels about 1/16" from the nominal plane of the pully. (C5 year 2003 with 85K miles and new tensioner & belt & no squeak). I only drive the 'Vette 800 miles per year and I'd like to make-do, if possible.