Crank pully wobble
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Joined: Sep 2005
Posts: 55
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Crank pully wobble
Changing the oil in my 05 MN6 yesterday letting it idle to warm up the oil and noticed and ever so slight wobble of the crankshaft pully. I know there is a TSB concerning this. Was wondering if anyone else has noticed this slight wobble. Reached down and could not move the pully and the bolt seemed tight, the belts are all tight and this may prevent being able to really tell if there is any problem. The car has only 15000 miles on it. I haven't experienced any audible noise and the ribs in the belt seem to be Ok also. Appreciate any input.
Advanced
Joined: Nov 2004
Posts: 77
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From: Lexington Ky
Get it checked out. There were a bunch of early build 05's that lost the pulley completely. The repair takes about 4 to 5 hrs and you dont want to watch! Pieces just keep being removed to place a small washer on the bolt. It gets ugly! And the original bolt cannot be reused. Good luck!
Safety Car
Joined: Jun 2004
Posts: 3,563
Likes: 2
From: Dallas Tx
I'd take it to a dealer and have them check the warranty history to see if the bulletin has ever been done. If not, I'd get it done. They replace the balancer, bolt, and washer in that bulletin. It is ugly if that comes off, better to just have it done.
I wouldn't just try tightening that bolt, that bolt shouldn't be disturbed, I'd get the complete bulletin done.
I wouldn't just try tightening that bolt, that bolt shouldn't be disturbed, I'd get the complete bulletin done.
Team Owner
Joined: Nov 2006
Posts: 21,136
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From: Long Island New York
Get it checked out. There were a bunch of early build 05's that lost the pulley completely. The repair takes about 4 to 5 hrs and you dont want to watch! Pieces just keep being removed to place a small washer on the bolt. It gets ugly! And the original bolt cannot be reused. Good luck!
Dont delay. If you can notice a wobble at idle imagine what its doing at 5000RPM!
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In extreme cases I have seen them walk into the rack, and once I saw one wear a hole in the timing cover that walked backwards. Get it checked out before it's a big issue. 
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Joined: Sep 2005
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Thanks everyone for your input. I guess my real fear is finding a dealer who can repair it without causing some other problem. Anyone know of a dealer that handles a lot of Corvettes in the Chattanooga Tn. area. Again thanks.
Instructor
Joined: Nov 2006
Posts: 221
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Curious what your VIN number is (if it's after the VIN# that included GM's supposed fix for this - IIRC diamond studded washer)
Here's a clip from a web search I found before buying my 05 C6 (mine is after the VIN listed - check your VIN no to see if it's before that number)
========
Bulletin Number: 05-06-01-001B
2005 Chevrolet Corvette with 6.0L Engine (VIN U - RPO LS2)
Built Prior to VIN Breakpoint 55111039
Condition
Some customers may comment on the Check Gages Light or the Battery Voltage
Low indicator coming on. Additionally, some customers may comment on the
accessory drive belt either slipping or being missing.
Cause
The crankshaft balancer bolt may have become loose.
Correction
Install a new crankshaft balancer pulley, washer and a new balancer pulley
bolt using the following procedure.
Parts Information
Part Number: 12557840
Bolt, Crankshaft Harmonic Balancer
Quantity: 1
Part Number: 12598247
Washer, Crankshaft Balancer
Quantity: 1
Part #: 12583637
Balancer, Crankshaft Harmonic
Quantity: 1
Here's a clip from a web search I found before buying my 05 C6 (mine is after the VIN listed - check your VIN no to see if it's before that number)
========
Bulletin Number: 05-06-01-001B
2005 Chevrolet Corvette with 6.0L Engine (VIN U - RPO LS2)
Built Prior to VIN Breakpoint 55111039
Condition
Some customers may comment on the Check Gages Light or the Battery Voltage
Low indicator coming on. Additionally, some customers may comment on the
accessory drive belt either slipping or being missing.
Cause
The crankshaft balancer bolt may have become loose.
Correction
Install a new crankshaft balancer pulley, washer and a new balancer pulley
bolt using the following procedure.
Parts Information
Part Number: 12557840
Bolt, Crankshaft Harmonic Balancer
Quantity: 1
Part Number: 12598247
Washer, Crankshaft Balancer
Quantity: 1
Part #: 12583637
Balancer, Crankshaft Harmonic
Quantity: 1
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Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
I had the pulley walk on my '05. Halfway shredded the belt. I wasn't looking forward to pulling the rack out to fit it. I called the dealer referencing the tech bulletin and noted that I had installed a cam. They said regardless of the aftermarket cam they were instructed to do the repair under warranty anyway. Aside from the dealer running down the battery from not parking it in reverse it was super!
Safety Car
Joined: Jun 2004
Posts: 3,563
Likes: 2
From: Dallas Tx
With that VIN, you want to get that bulletin done. At the Chevy dlr ask to have a tech do it that has done the bulletin before. It's a pretty straight forward job. But there are real specific steps for getting the new balancer on the right depth on the crank snout. You don't just impact it on. It goes on to a certain measured depth, then a specific torque sequence. If they follow the bulletin step by step, it will last forever.
You want to do it before it slips, because that can damage the crank snout.
You want to do it before it slips, because that can damage the crank snout.
