Crankshaft Run-Out Test
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Colorado
Crankshaft Run-Out Test
I've had my Harmonic Balancer replaced by GM dealership. After the replacement, I still see significant HB wobble. A different dealership service manager suggested having a crankshaft "run-out" test performed by the GM dealership who performed the repair. I have 1 month remaining on my limited power train warranty, which includes the HB and internal parts. Has anyone performed, or had someone else conduct the "run-out" test? What does this entail? My concern is what else could be wrong after the HB is replaced and there's still considerable wobble. Is there a known crankshaft, or related parts, defect in LS motors that would cause the HB wobble, other than the HB? I assume the GM dealership didn't pound the HB back on the crankshaft with a hammer, but who knows. What other issues are possible if the new OEM HB is not damaged? I don't have any belt chirp at this time. Thank you for your time.
Last edited by SFCBOGLE; Dec 23, 2018 at 12:51 PM. Reason: rewording
Pro
Joined: Feb 2017
Posts: 509
Likes: 52
From: DFW Texas
I have a thread with a video link to my "bolt wobble" issue. I replaced my HB (which wasn't wobbling I just wanted to do it while I had the time) with a race spec Powerbond and although the HB has no wobble, the crank bolt does. I used an ARP bolt and torqued it correctly with their procedures. Some have suggested that the bolt might be off center or possibly an issue with my crank. Car runs fine and no chirping from the belts. I'm kinda in your situation in that I have no clue what to do or what might be causing it. I'd hate to tear it all down again if it's nothing and if it is something bigger than just the bolt (as in the crank), I have no clue what I'd do then. It's not like I have the ability to remove the crank and fix it if it needed it. Let me know what you decide to do! Good luck
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Safety Car
Joined: Nov 2007
Posts: 4,435
Likes: 874
From: Bay Area CA
I've had my Harmonic Balancer replaced by GM dealership. After the replacement, I still see significant HB wobble. A different dealership service manager suggested having a crankshaft "run-out" test performed by the GM dealership who performed the repair. I have 1 month remaining on my limited power train warranty, which includes the HB and internal parts. Has anyone performed, or had someone else conduct the "run-out" test? What does this entail? My concern is what else could be wrong after the HB is replaced and there's still considerable wobble. Is there a known crankshaft, or related parts, defect in LS motors that would cause the HB wobble, other than the HB? I assume the GM dealership didn't pound the HB back on the crankshaft with a hammer, but who knows. What other issues are possible if the new OEM HB is not damaged? I don't have any belt chirp at this time. Thank you for your time.
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Colorado
Did the HB coming out have visible wear on the silicone seal that is between the hub and outer ring? Was the HB bolt loose and caused the wobble? If no evidence of HB failure was present, then take it back to the repairing dealer for advice. If they say the wobble is "normal" then, go to another dealer.
Unfortunately, the servicing dealership didn't state what the condition of the HB was, only that it was repaired. He didn't identify if there was a loose bolt either. I took teh car to another GM dealership and asked for a diagnostic (told them I would pay the $135 for it). They said take it back to the dealer that covers the warranty. Note: the dealerships are less than 2 miles apart, so I may not be getting a fair analysis. I will visit a dealership 50 miles away in hopes they aren't somehow "connected."
I do hope an impartial (read competing) GM service manager will take my money and document any possible issues that may indicate something other than another bad HB...like a crank not running true (my unprofessional diagnosis). Thanks everyone for your feedback! Merry Christmas.
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Colorado
Beef97,
Thank you for the reply and background on your situation. I'm returning to the dealership to report belt chirp when the engine is still cold. I will revisit the dealership to get the issue documented again. I will post back here what the resolve is. Thank you for the quick, detailed reply.
Thank you for the reply and background on your situation. I'm returning to the dealership to report belt chirp when the engine is still cold. I will revisit the dealership to get the issue documented again. I will post back here what the resolve is. Thank you for the quick, detailed reply.
Thank you for the reply and background on your situation. I'm returning to the dealership to report belt chirp when the engine is still cold. I will revisit the dealership to get the issue documented again. I will post back here what the resolve is. Thank you for the quick, detailed reply.
Safety Car
Joined: May 2011
Posts: 3,807
Likes: 508
From: Oshawa, Ontario
You have another bad OEM balancer which is not an uncommon occurence.they are not a high quality part and I have replaced a dozen of them over the years.some of them never made it home from the dealer with 35 miles on them when the cars were new.I replaced mine with a new OEM and it only lasted 4,000 miles.Didn't realize at the time how bad the OEM was.When I removed at 4,000 miles there was no evidence of anything being wrong with it other than it being noisy.I then replaced it with an ATI hb and no issues since.If you have run out in the crank it would damage your front cover seal and end up leaking oil through it.
Last edited by irok; Dec 25, 2018 at 11:36 AM.
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Colorado
You have another bad OEM balancer which is not an uncommon occurence.they are not a high quality part and I have replaced a dozen of them over the years.some of them never made it home from the dealer with 35 miles on them when the cars were new.I replaced mine with a new OEM and it only lasted 4,000 miles.Didn't realize at the time how bad the OEM was.When I removed at 4,000 miles there was no evidence of anything being wrong with it other than it being noisy.I then replaced it with an ATI hb and no issues since.If you have run out in the crank it would damage your front cover seal and end up leaking oil through it.
Yesterday, I was checking the wobble again, seems to be getting worse. I inspected the "new" HB even closer this time. I noticed a painted blue X on the HB and what looks like wear (not what I think a brand new one with less than 300 miles would look like). The painted blue X on the front of the HB raises a question....does the manufacturer normally put a painted blue X on a new part? I've seen things like that on refurbished and used parts, but never a new part. Anyone seen this before or have any knowledge regarding a part having a blue X painted on it?
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Colorado
Thanks for the feedback. I've heard the OEM HBs are crap, numerous posts. It's a shame GM never recalled. The dealer wouldn't install an aftermarket HB for me, and I don't have the tools/facilities to do the job myself. Since it's currently under warranty it made since to have the GM dealer perform.
Yesterday, I was checking the wobble again, seems to be getting worse. I inspected the "new" HB even closer this time. I noticed a painted blue X on the HB and what looks like wear (not what I think a brand new one with less than 300 miles would look like). The painted blue X on the front of the HB raises a question....does the manufacturer normally put a painted blue X on a new part? I've seen things like that on refurbished and used parts, but never a new part. Anyone seen this before or have any knowledge regarding a part having a blue X painted on it?
Yesterday, I was checking the wobble again, seems to be getting worse. I inspected the "new" HB even closer this time. I noticed a painted blue X on the HB and what looks like wear (not what I think a brand new one with less than 300 miles would look like). The painted blue X on the front of the HB raises a question....does the manufacturer normally put a painted blue X on a new part? I've seen things like that on refurbished and used parts, but never a new part. Anyone seen this before or have any knowledge regarding a part having a blue X painted on it?
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Safety Car
Joined: May 2011
Posts: 3,807
Likes: 508
From: Oshawa, Ontario
I have never seen a blue X on any GM hb and as far as I know no one refurbish's them.May be something the tech put on there for whatever reason.I mark new hb's and bolt head with white paint stick once job complete so that I can see if bolt or hb moves.What do you mean by looks like wear.Theres nothing to wear on them.It and the bolt should obviously look brand new.The bolt also can't be reused.Is the bolt new?If not it will need to be replaced as the torque to yield bolt may back out on it's own.On the work order it should have p/n and charge for new bolt.If not on work order they didn't change it
Last edited by irok; Dec 27, 2018 at 09:49 AM.