► ► OH MY GOD, MY CRANK PULLEY SPUN...WHAT NOW? @ CoW ◄ ◄
03-01-2009, 01:11 PM
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St. Jude Donor '07-'08-'09-'10-'12-'13-'14
► ► OH MY GOD, MY CRANK PULLEY SPUN...WHAT NOW? @ CoW ◄ ◄
OH MY GOD!
My CRANKSHAFT PULLEY (balancer) SPUN!!!
WHAT NOW?!?!?
By now, most of us have figured out that this is a somewhat common problem with late Corvettes. The crank pulley (balancer) retaining bolt is "torque to yield" and as large a bolt as it is, and despite it's intended engineering whatever, It's not much more than a "cash cow" for GM as every time this bolt is removed...you MUST replace it. It's been causing millions of dollars of warranty issues for them and likely an equal dollar amount of distress for corvette owners not still covered under the general's warranty.
Engines of yesteryear used "REAL BOLTS" where you could make em' tight and re-use them over and over....Kinda like an ARP bolt that has an almost infinite lifespan....provided you don't over stretch it. The cylinder head bolts on LSx engines are also torque to yield, and YES, You have to replace them EVERY TIME as well.
Also, these engines are balanced differently than earlier engines so that the crank pulley can go on any way you like....You'll notice there is NO CRANK KEY like your old small and big block chevy had. The keyway was kinda nice because it helped index the pulley and kept it from spinning on the nose of the crank.
Recently, I got a call from a customer named Mike with an 05 C6 mn6. He was in a panic because he felt that his balancer had spun and it was making a "chirping" sound.
Knowing how serious this can be...I advised him NOT to drive or start the car and get AAA to tow it to the shop. When the car arrived, his pulley had a very noticeable "WOBBLE" to it and it was, like he said, CHIRPING.
Here we go... After lowering the front chassis...and removing the steering rack....We removed the pulley.
TO MY SURPRISE...The CRANK was PERFECT!
What happened was the outer ring of the (let's use the correct term here) ELASTOMETER had misaligned from the crank hub and made the pulley wobble causing the belt to chirp like a bird.
Mike (and I) kinda thought he was looking at a crank job at the least and possibly that expensive high compression stroker motor with the new "CoW CAM"....This time, that option was not in the budget.
I called mike and explained that everything was cool....The simple fix here was a nice underdrive pulley and a slightly shorter belt with a NEW bolt. Bada BING! Fixed! A quick FREE RE-TUNE and some extra horsepower...and Mike was off to the races with a smile.
Mike got off REALLY EASY. EVERYONE, take note here... DO NOT DRIVE YOUR CAR IF YOU SUSPECT YOUR BALANCER HAS COME LOSE!!! While we would like all stories to end as nicely as his did, there is a darker side to this problem....
ABOUT 2 WEEKS AGO....
...This nice guy named Tim brings his C5 from Michigan all the way to Corvettes of Westchester for a clutch and some tuning.
My guys begin to dismantle the drivetrain when Tim mentions his crank pulley had previously spun and was wobbling AGAIN!
OH JEEZ...Here we go again. Having recently repaired an H2 HUMMER with a supercharger (successfully) and saved the motor....I figured I was in for another battle to the death.
As we started to remove stuff from the car....The situation got worse and worse.
First the crank pulley...NOT GOOD. Then the waterpump and timing cover...OH MY GOD!..... next...The oil pump....DIDN'T WANNA COME OFF!!!
Tim, my friend, We'll take good care of her...You'll have to leave here here for a few weeks....I said.
Below is a hand full of photos showing the dangers of a "SPUN PULLEY".
We took these photos with our new high powered "CoW CAMera" he he...
Have a look....These photos show how the metal from the CRANK and PULLEY get into the oil pump and circulate through the entire engine destroying the oil pump, crankshaft, bearings, and pistons not much unlike cancer.
DO NOT IGNORE THE WOBBLING PULLEY PROBLEM!
THIS COULD HAPPEN TO YOU.
STAY TUNED FOR THE re-BUILD UP OF TIM's NEW CAMMED STROKER MOTOR WITH THE BLOWER...Later in this thread...
FIRST...THE METAL DEBRIS IN THE BEARINGS...
Here's the nose of the crank with the oil pump drive... This crank was "PINNED" once and it failed....then drilled for a second crank pin.... Looks like a PIT BULL chewed on it...
Here's the metal in the main bearings...
The oil pump took some "HEAVY METAL" and nicely distributed it throughout the motor...
Finally, the metal from the pulley and crank nose actually got up into the pistons...
There you have it. Be sure your shop DOES NOT RE USE the crank bolt. USE LOCTITE! and if possible....Use a quality "CRANK PINNING" kit to drill and dowel (index) the pulley so it can not spin....ESPECIALLY for forced induction cars where the blower is driven from the crank pulley.
Again, of you suspect your crank pulley has come lose....HAVE SOMEONE competent check it out for you.
Left unattended...this can become an expensive MESS!
As Tim's vehicle goes back together we'll post the progress in this thread.
STAY TUNED!
CHUCK CoW
03-01-2009, 01:34 PM
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St. Jude Donor '07
Great write up Chuck 
I have been dealing with a rash of these pulleys in the last year . It seem's that as these age the inner ring pulls away and the bird chirp begins.I have seen it where the outer ring backs onto the chain cover almost wearing through.
Great advice here . I would add that even a high HP build with 450RWHP
or more should be pinned for that added measure of prevention.
See ya soon Chuckie
Manny@E.C.P
I have been dealing with a rash of these pulleys in the last year . It seem's that as these age the inner ring pulls away and the bird chirp begins.I have seen it where the outer ring backs onto the chain cover almost wearing through.
Great advice here . I would add that even a high HP build with 450RWHP
or more should be pinned for that added measure of prevention.
See ya soon Chuckie
Manny@E.C.P
03-01-2009, 01:44 PM
#3
Drifting
On the lighter side- my new forged 7.0L had the pulley come loose till the pulley was riding on the steering rack(you could hear it rubbing), I removed the pulley, inspected it and re-installed(with a new bolt) the pulley and haven t had any further problems from it whatsoever. This has been 6 mos ago. I was one of the "lucky" ones.. Im glad it didn t toast my new motor! 
Im glad it didn t toast my new motor!
Or did the pulley separate? If it spun, was it a blown engine with a lot of boost?
03-02-2009, 12:00 AM
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St. Jude Donor '07-'08-'09-'10-'12-'13-'14
Not realy sure.....
Not really sure....It came in that way...
I think It spun at like 8 psi with the small pin you see...***I THINK***
Maybe it sheared....
I think the fat pin was an attempt to save the crank the second time....
By the looks of it, I think it was too late the first time it happened.
We had an H2 Hummer in here with a blower recently and it was previously repaired TWICE for the same thing.
Fortunately, The pulley took most of the damage and the crank was able to be saved with some creative pinning.
The guy in the Hummer before me put like 6 HELI COILS back to back and a huge bolt and crossed his fingers in hopes it would work....
What he didn't realize was that he bottomed the crank bolt BEFORE the pulley was tight...
That pulley wasn't tight from GO.
But, a few thousand miles later....My repair is still working. What a fight that was.
Chuck CoW
Last edited by Chuck CoW; 03-02-2009 at 12:03 AM.
03-02-2009, 01:28 AM
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Chuck, i usually don't go into this section since i really don't know what all the words mean but i do know the bare basics of how an engine works.
If you would have the time, could you explain what exactly was the problem w/ the harmonic balancer/crankshaft pulley?
To my understanding it had a spun bearing. Meaning it spun poorly leading it to not balance the vibrations correctly that come from the engine. These vibrations lead to excessive belt wear a.k.a the chirping the owner was hearing?
So besides the obvious belt wear. What was the problem originating from the balancer that could of made the owner need an overhaul of the motor?
What are the effects of the spun bearing? Would the balancer spin slower or completely stop leading it to mess all the accessories on the drive line belt? But then that would be noticed immediately as it would be shown on all the gauges and even throw a check engine light. So if the driveline belt is still spinning I would think the wobble itself i think would be harmless besides eating the belt.
Where is this metal coming from that you are mentioning? Is it from this 1 time use bolt crapping itself? If that is the case, then i see where the problem is
Metal shards in engine
What causes this bolt to stop working and disintergrate?
Sorry for all the questions. But i try to be like a sponge learning all i can.
One last question i forgot.
You said there is no crankkey (the marker for balace spot) on this because the balancer works upon any position installed.
But from the GM Service manual
It agree's with you on the no keyway, but then say's it must be installed in original position.
Im a future DIY mechanic since i currently make 7.50/hr and cannot afford to pay mechanics outside of family
but i do know the bare basics of how an engine works.If you would have the time, could you explain what exactly was the problem w/ the harmonic balancer/crankshaft pulley?
To my understanding it had a spun bearing. Meaning it spun poorly leading it to not balance the vibrations correctly that come from the engine. These vibrations lead to excessive belt wear a.k.a the chirping the owner was hearing?
So besides the obvious belt wear. What was the problem originating from the balancer that could of made the owner need an overhaul of the motor?
What are the effects of the spun bearing? Would the balancer spin slower or completely stop leading it to mess all the accessories on the drive line belt? But then that would be noticed immediately as it would be shown on all the gauges and even throw a check engine light. So if the driveline belt is still spinning I would think the wobble itself i think would be harmless besides eating the belt.
Where is this metal coming from that you are mentioning? Is it from this 1 time use bolt crapping itself? If that is the case, then i see where the problem is
Metal shards in engine What causes this bolt to stop working and disintergrate?
Sorry for all the questions. But i try to be like a sponge learning all i can.
One last question i forgot.
You said there is no crankkey (the marker for balace spot) on this because the balancer works upon any position installed.
But from the GM Service manual
* For manual transmission applications, note the position of the crankshaft balancer before removal. The balancer does not use a key or keyway for positioning. Mark or scribe the end of the crankshaft and the balancer before component removal. The crankshaft balancer must be installed to the original position. If replacing the crankshaft balancer, note the location of any existing balance weights, if applicable. Install new balance weights into the new crankshaft balancer, if applicable. Crankshaft balancer weights must be installed into the new balancer in the same location as the old balancer. A properly installed balance weight will be either flush or below flush with the face of the balancer.
* Do not use the crankshaft balancer bolt again. Install a NEW crankshaft balancer bolt during final assembly.
* Make sure that the teeth of the flywheel holding tool mesh with the teeth of the engine flywheel.
* Do not use the crankshaft balancer bolt again. Install a NEW crankshaft balancer bolt during final assembly.
* Make sure that the teeth of the flywheel holding tool mesh with the teeth of the engine flywheel.
Im a future DIY mechanic since i currently make 7.50/hr and cannot afford to pay mechanics outside of family
03-02-2009, 11:30 AM
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St. Jude Donor '07-'08-'09-'10-'12-'13-'14
Good questions......
Chuck, i usually don't go into this section since i really don't know what all the words mean but i do know the bare basics of how an engine works.
If you would have the time, could you explain what exactly was the problem w/ the harmonic balancer/crankshaft pulley?
To my understanding it had a spun bearing. Meaning it spun poorly leading it to not balance the vibrations correctly that come from the engine. These vibrations lead to excessive belt wear a.k.a the chirping the owner was hearing?
So besides the obvious belt wear. What was the problem originating from the balancer that could of made the owner need an overhaul of the motor?
What are the effects of the spun bearing? Would the balancer spin slower or completely stop leading it to mess all the accessories on the drive line belt? But then that would be noticed immediately as it would be shown on all the gauges and even throw a check engine light. So if the driveline belt is still spinning I would think the wobble itself i think would be harmless besides eating the belt.
Where is this metal coming from that you are mentioning? Is it from this 1 time use bolt crapping itself? If that is the case, then i see where the problem is Metal shards in engine
What causes this bolt to stop working and disintergrate?
Sorry for all the questions. But i try to be like a sponge learning all i can.
One last question i forgot.
You said there is no crankkey (the marker for balace spot) on this because the balancer works upon any position installed.
But from the GM Service manual
It agree's with you on the no keyway, but then say's it must be installed in original position.
Im a future DIY mechanic since i currently make 7.50/hr and cannot afford to pay mechanics outside of family
but i do know the bare basics of how an engine works.If you would have the time, could you explain what exactly was the problem w/ the harmonic balancer/crankshaft pulley?
To my understanding it had a spun bearing. Meaning it spun poorly leading it to not balance the vibrations correctly that come from the engine. These vibrations lead to excessive belt wear a.k.a the chirping the owner was hearing?
So besides the obvious belt wear. What was the problem originating from the balancer that could of made the owner need an overhaul of the motor?
What are the effects of the spun bearing? Would the balancer spin slower or completely stop leading it to mess all the accessories on the drive line belt? But then that would be noticed immediately as it would be shown on all the gauges and even throw a check engine light. So if the driveline belt is still spinning I would think the wobble itself i think would be harmless besides eating the belt.
Where is this metal coming from that you are mentioning? Is it from this 1 time use bolt crapping itself? If that is the case, then i see where the problem is
Metal shards in engine What causes this bolt to stop working and disintergrate?
Sorry for all the questions. But i try to be like a sponge learning all i can.
One last question i forgot.
You said there is no crankkey (the marker for balace spot) on this because the balancer works upon any position installed.
But from the GM Service manual
It agree's with you on the no keyway, but then say's it must be installed in original position.
Im a future DIY mechanic since i currently make 7.50/hr and cannot afford to pay mechanics outside of family
Good questions.
In the first case, this fella DID NOT have a pulley spin on the crank. The outer ring of the pulley actually became mis-aligned likely from high rpm use.....over and over.
In the second case, the blown C5, a small pin was used to stake or pin the pulley to prevent rotation, but it was not enough at high boost (8psi) to keep it from rotating....Most of the damage was done by the pulley rotating over the small pin....By that time the damage was done the second attempt to pin the crank was not going to help.
When the crank pulley spins on the crank nose, it literally GRINDS and sometimes MELTS the metal off the crank and pulley....Usually the stock balancer is made of a type of powered metal or "cast" material that almost looks like fine metal "sand".
Since the pulley extends into the engine (behind the front crank seal) and rests against the oil pump....All of the powdered metal "sand" gets directly into the oil pump and spreads throughout the engine like a cancer getting EVERYWHERE!
That's the reason this can be soooo destructive.
Chuck CoW
03-02-2009, 11:32 AM
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St. Jude Donor '07-'08-'09-'10-'12-'13-'14
Yes, it did....
If you look in the photos, the "skinny" pin could never have held a BLOWN pulley on....I've never seen anything like that pin....we use a much fatter pin.
Chuck CoW
03-03-2009, 11:42 PM
#12
Le Mans Master
Ok,,a question. Stock motor with 67k on it,,no problems so far,,,would it be a good idea to replace the bolt as a preventive measure,,or just let it ride?? Thanks in advance!!!
