My ATI harmonic balancer appears to have possibly split and come loose on my 2005 with 120K miles. The balance was upgrade at about 40K miles so this one has 80K on it. Oil is leaking from the seal. I plan to dig into this and have been doing the research for the best way to go about it. I’m thinking lowering the cradle requires a little more disassembly, but is easier and safer in the long run. I’ll probably make the final call as I dig in. Before I dive in, I thought I’d see if any of you more experienced enthusiasts have any thoughts about what I’ll find? Does this look normal? The balancer is moved out and resting right against my steering rack. There is a decent gap between the serpentine grooves and the AC belt grooves. Did the bolt come loose or is there a chance it broke? Do you think I’m going to need anything other than a new HB, Bolt, Seal and belts? Is there anything else I should consider changing while I’m in there? Thank you in advance for reviewing this and whatever knowledge you are willing to share.

Top View up against steering rack.


View from under the car. HB appears to be split

 

My first thought is the bolt wasn't tightened properly when replaced and the balancer is now "walking" out on the crank snout resulting in a compromise of the oil seal. Hard to tell from the pics of your concern that the damper has split, There is a separation of the 2 pulleys on the new ones and I cannot see anything larger than the normal gap. You definitely need this one fixed.

Let us know the fix.

GD

 

Another ATI bites the dust ...

Next, get a PowerBond

 

I just went with a stock GM during my build. My tech said that they are not as bad as everyone says they are.

 

You may be lucky, you may not. There are too many documented failures to ignore. I've used Power Bonds on several builds and have never had a problem. Not sure I've ever heard of one failing. Plus, I think they are less expensive than a stock unit.

 

Or an ASP. Mine is a 25% UD, been on for over 10 years, 60,000 miles. No issues.......

 

Well the one I took off had 188,000 miles on it and I replaced it because everything else was getting replaced.

 

Thanks for the replies. I'll dig in next weekend and see what I have before buying parts. If I have to replace the HB I'll probably go with the PowerBond. There are so many to choose from looking at Summit racing. Is there a specific one you recommend? What is the advantage of 25% UD? I suspect less power required, but the accessories wouldn't turn as fast either. Doesn't that require a different size belt?

 

I believe there is a separate P/N for the LS engines with the dry sump oiling system, but for for the LS2 and LS3 with wet sump, you need PowerBond P/N: PB1117SS

PowerBond Race Performance harmonic balancer ...

https://www.summitracing.com/parts/pbb-pb1117ss

Jeeeze ... they are getting very popular and have really gone up in price ... From $227 when I bought mine 3 years ago from Summit to $281 right now ! . .

BTW ... forget the UD size. Get the standard diameter.

And another tip ... Have it 'pinned' just in case you ever decide to install a supercharger on the engine. Pinning it will cost very little when replacing the balancer.

 

I'd say go 10% under if you care about power output. If you add a cam into the mix, you'll more than likely up the idle just a bit anyway. Even if you don't add a cam, at stock idle speed, you still have plenty of speed on the accessories to get along. Might be an issue if you have a sound system that draws a lot of power and irritates all within earshot. Otherwise, there's not much downside to the 10% under. Anytime you can add power without detracting from manners and efficiency, it's all good. Not saying I'd pull a perfectly good balancer to go underdrive. No way I'd go back stock size if I had to change it though.

 

The crank bolt is a one-time use design. If you have to loosen it, replace it. The GM part works fine; it's what my tuner/installer used.

 

I got it apart and found the ARP bolt loose. The balancer walked forward on the crank snout and contacted the steering rack. No damage to either part other than slight scuffing. It moved out far enough to lose the Oil Seal. So now the big question. Should I reinstall the ATI balancer? It appears to be in good shape, but it does have 80K+ miles on it. After just sinking $2500 into my breakdown while traveling from Cleveland to Duluth and another $500 into my Yukon AC, I'm especially sensitive to another $300. I'll probably be spending that for belts, idler wheels and tools. But if there are strong opinions, that's what I'm looking for. I tend to lean towards replacing it to reduce the risk of not having to take this apart again or be stranded again far away from my garage and relying on other mechanics. I'm 60 now and rolling around under the car isn't as fun as it used to be. The guy I bought the car from 4 years ago seemed to be a competent mechanic and had lots of high $ toys. Many with mods he did himself. It's hard to imagine he would have installed it incorrectly, but who knows, maybe his torque wrench was out of calibration. I'm going to make sure mine is in calibration before trusting it with this much torque! All the other idler wheels feel really smooth with no detectable wobble / play. I plan to take this car from 120K to 200K+ before upgrading to a C7 Grand Sport or who knows, a C8.
This is where you guys talk me into or out of the new balancer! I appreciate your opinions!

 

I think the big question is, is the dampener still tight on the crank? It's supposed to be a very tight fit, if not it will spin and cause more damage. If the ID of the dampener is still good, ATI's are rebuildable, so you could replace the O rings and it would be like new. If it's a little bit loose maybe you could reuse it and pin it to ensure it doesn't spin

 

Now that you identified the problem, I would say the ATI balancer is fine to reuse. If you are sure your have an ARP bolt, then you can reuse that as well. If not sure, then buy a new one. You should also replace the oil seal. When you put it back together be sure you tighten the bolt to the proper torque spec and lock the flywheel to be sure the engine doesn't turn over. Manual can be put in gear, automatic you have to remove the starter and put in a locking pawl tool on the flywheel.

Good luck on the unfortunate repair.

GD

 

It was still very tight. I used the ARP bolt, w/o washer, as a set platform for my puller. I had to use the puller all the way to about 1.5 threads on the ARP bolt before it came loose. I tried to wiggle the HB by hand before that and nothing. I heard the ATI's are rebuildable and will research that... I think of the abuse track enthusiasts put these things through compared to my occasional romps on a twisty country road and seldom throwing her down a couple gears with a sprint to red. I mean most vette's that even come close to being used for what they are built for see 10x the driving I dish out. If I decide to reuse or rebuild I'll probably buy the pin kit and pin it. Even though I'll never super charge it, it's a piece of mind as I throw it from 4500 down a gear to hit a quick 5500 sprint to 6500+. 2nd gear can get you in a lot of trouble, 3rd is worth a $550 ticket on the Indiana turn pike with Mustang Cobra 500! Thanks for your feedback.

 

Thanks - absolutely buying a new seal. It's an ARP bolt and I'm going to ensure my torque wrench is calibrated. I wasn't aware you can screw up your torque wrench using it as a breaker bar and I have done that a few times over the years. I don't want to screw this up cuz I enjoy fishing and golf too much to be under the car. Thanks again for the feedback.

 

As I recall, the crank bolt is a one-time-only use. It must always be replaced with a new one any time the old bolt is loosened. When I had an installer/tuner do a cam swap 3 years ago on my C-6, He bought a new GM crank bolt when he installed my ATI balancer. Possibly reusing the crank bolt on his in the past caused it to loosen up over time. If he's going to pull the balancer, it's going to require dropping the engine cradle - a lot of labor. I would say, anytime such labor is involved, it would be a good idea to get the balancer off, inspect and micrometer the crank to see if there's any damage (sounds like, from what he's saying, there isn't). But, the labor involved does warrant a close examination of the situation.
8/9 update - Just checked with vendor of ARP bolts and was told the crankshaft bolt is not a torque-to-yield type. Choose the bolt you want but GM uses this type for a reason.

 

It was stated he has an ARP crank bolt. Why anyone still uses the one time use GM bolt is beyond me! I have had my ATI balancer off more than a few times and the 27mm 12pt ARP crank bolt has paid for itself many times over. Lock the crank with the flexplate tool and 240 lb-ft after using an install tool to get the damper on I use ARP hardware anywhere I can. The TTY GM stuff truly is junk.

 

Since this is a lot of labor in my opinion and not the easiest of jobs.
I would replace the HB with a new one and a new bolt, plus your seal.
Extra $400 now or a possible redo in to soon upcoming miles.
+1 for the torque wrench recalibration.
Good luck with your decision.

 

Just a suggestion...
since you are going to have the car apart and you plan on keeping the car; you may want to swap out (or at least check) the motor mounts.
I have a 2009 with 95k, while changing out the harmonic balancer, I also changed motor mounts since they were leaking. I dropped the crossmember to get clearance to both.

The motor mounts in these cars are hydraulic and do not last forever.