boss302

City traffic and stop and go highway jams are making me think of moving up from my /03, Z06 to a C6 with an automatic, but after searching through a lot of threads about harmonic balancers falling off, I am having reservations about it. There are no shops in the area that I would trust to change it and at this point, it is a bigger job than I feel like doing. Here are a few questions. What exactly is the failure mode? Do they always start to wobble before failing and does anyone have a feeling about the time from start of wobble to failure? Are the newest of the C6 models at the same risk as the oldest? I gather this is a "luck of the draw" thing and not related to mileage. Sorry to pursue a well worn issue, and thanks for any helpful info.

Hells

They all have a tendency to fail. I got lucky and had the original as well as 2 replacement GM balancers fail on my 07. I now have a Powerbond underdrive pulley which has been flawless so far for the past 3.5 years.

Mike Green9

Hi.

All the years of the C6 are using the same style harmonic balancer from GM. The 2 concentric components are separated by rubber, and that rubber is prone to failure.
Also, there is no keyway keeping the balancer in place - just a press fit, tightened by the crank bolt. Over time the bolt can loosen and the balancer starts to slip. (GM started using a friction washer with the 2006 model year - didn't help much.) If the balancer starts to slip on the crankshaft, you will hear chirping and squealing.

Idle the engine and look at the balancer for wobble. Have someone rev the engine and see if the pulley moves outward. If it does, then a failure is in the making. If it does not, don't worry about it. A small amount of pulley wobble (1 - 2 mm) is acceptable. Also, look for belt fraying.

I cannot tell you how long it will take to completely fail once it starts to go bad. Driving habits (right foot syndrome ) will dictate that. I have read a post that suggested that because old belts stretch, this may promote the premature rubber failure. So changing belts might be a way to avoid a problem.

It's a big job to change because the steering rack has to be pulled to allow the removal of the balancer. Figure on 6 to 8 hours by someone who knows what they are doing $1,200 - $1,500, plus the balancer, and a wheel alignment.

Best to replace with a balancer from ATI or SLP - NOT GM.

My '08 has 26,400 miles with no balancer issue. I do worry about it though.

However, this should not stop you from buying a C6. They are awesome!

Hope this helps,

M....

89talon

I did mine last week. I just purchased a 2005 vert C6 with 90k. Of course it started chirping once the weather warmed. A shop had attempted and failed by welding the nut to the balancer. I bought the ATI kit which includes a new bolt and timing cover seal with the three piece balancer. They pinned the bolt to the balancer so it will never come loose. They make a jig for the drilling for the pin. The mechanic that did the work had never done a replacement before so it was several hours labor. I paid $448.00 for balancer and kit and $900.00 in labor. I am blissful with the results. The car has no rattles, squeaks or odd noises' of any sort coming from the car. And I flog it regularly! lol. Don't hesitate to buy a car in need of a balancer. Let us know what you buy as I live vicariously threw several members on this site and others.

BlindSpot

A harmonic balancer should not wobble AT ALL...thus the name of the part...Harmonic...Balancer. No amount of wobble is acceptable with a 20 something pound wieght spinning at the end of a high horsepower high torque engine at 6000 + RPM.

What would anyone do if they saw the slightest wobble in the - Alternator pulley, the waterpump, the PS pump pulley or the tension pulley?

The notion that a slight amount of wobble in the HB is OK comes comes from the guy who takes it in to the Chevy dealer. Tech says you have a bad harmonic balancer. Owner says how much to replace it? Dealer says $1200. Owner throws a fit and says THAT'S RIDICULOUS!!!!! Dealer says, well....a small amount of wobble probably isn't going to hurt anything. How about just watch it. If it gets worse then change it.....

BlindSpot

That's funny - I was SURE I was the only one. I designed/built my own drill jig. Thought there was no other C6 on the planet pinned this way. I am boosted so I insisted I would do this.

I've had some "clowns" say - "Duh...Hay man...How ya gonna get that outa there if ya ever have ta change it man?" I just roll my eyes....

Mike Green9

Yes I do agree - no wobble between the crank and the balancer.

What I meant was that as the engine is rev'd, the pulley (outer part of the balancer) may move outward a mm or two. That would be the distortion of the rubber portion of the balancer under the load of the belt.. At least that is what I have observed on any of the LS* engines with stock balancers that I have seen.

Sorry for the confusion.

M....

Barndog Buddha

Well I might be mistaken but I believe the c5s also have the same problem with the hb.
It is not just a c6 problem.

buckmeister2

I have never read one single post about the HB actually falling off, though I am sure it has happened. There have been a lot of posts about "what would happen"..."worst case scenario", and it could happen, just as a wheel could fall off.

It can be replaced for about $400 to $700 in labor, depending on location. You will see it wobbling quite a bit as it gets worse, and will hear whine when it is bad. It is not the end of the world, or anything to fear. I have a friend whose HB has been wobbling for 30,000 miles, and he drives his car everywhere.

Turbo6TA

I believe it has been a problem since the first LS1 came out in 1997 (first year for the C5).

HBsurfer

We had one regular here on the forum who had a balancer come apart. I wish I could remember the name but it is not coming to me. Regular poster here and it was last year. It did a lot of damage.
Anyway, that is the only complete failure I have read about here.
I bought my car knowing the balancer was wobbling. I pointed it out to the previous owner and he dropped his price by $1500.00..
For me, "keeping an eye on it" was not an option. I don't knowingly leave any bad part on any of my vehicles so I just put on an ATI the day after I bought my car.
Don't let it keep you from buying. LS1, LS2 and LS3 all have the same problem.
Budget the money into your purchase and never worry about it again. Or, you can "keep an eye it"

Jmhornz71

My balancer made it to 106k miles before being replaced. I replaced with a stock balancer as my dealer guarantees original GM parts and labor for life

z06inVB

When I bought my 2012 coupe it was literally wobbling from day one. At first dealer said bad belt and replaced it but by 3k miles it was replaced. Now at 60k miles I have had no issue with the replacement. Yet ......

jmeirhofer

I bought my C6 a few months ago. I knew about the HB issue and made sure to check it on the car I bought. I also had them give me a 24mon/24k mile warranty which specifically called it out in the what's covered section. Of course there were a number of things I looked for to make sure they were covered.

I don't even think about it unless it comes up here. I say buy one and be happy. I have not been able to wipe the smirk off for three months now

choppychop

The stock one is crap, count on changing it. Around $800 parts and labor...

dphins

Mine didn't come apart, but it did throw the belt because the harmonic balancer was moving forward. (29000 miles)

pure zen

I just had my HB replaced at 23K miles....went with the ATi and spent a little more $$ but I don't want to have this issue again. $400 for the part from Summit, $34 for the bolt kit.....$510 for labor. Peace of mind is worth something on long trips, IMO.
Next up issue.....the dreaded lock in Park issue. Any you tube videos of removing the center console in the '05 C6? Thanks for any directions....

Unreal

All LS motors have the issue. So his c5 is just as likely to have it a c6, or chevy truck, or GMC van.

windyC6

NAHHHH. This just depends on any one individuals opinion on what the def of "Slight" is. You go out and check 1000 balancers from any auto and you may find 100 or less of them that run absolutely 110% straight. Most will/can have a "very slight" wobble.....and some may have a little bit more than a "slight" wobble but still not enough to cause concern. A "very slight" wobble is really of no concern for just as the above post tries to suggest thats why the balancer is there. So if your C-6 does have a "very slight" wobble, don't let the sky fall in on you just yet. But yes these C-6's can/do develop a "bad" wobble which will of course need to be addressed......whether yours meets such criteria is something you'll have to have checked by someone, just be sure his/her name isn't Chicken Little...... .

sabersaw30

Wow didn't realize how much i saved doing it myself. Amazing how much they charge for install of a hb!