Problem with C5
Discussion
I'm having a small problem with my C5, I'm hoping this is a common problem but doubt it....(Apologies in advance for the essay)
I've had my C5 now for about a month and done over 1000 miles of trouble free motoring
. That was until last week. Basically while driving I heard a bizarre noise. I stopped and noticed the Crank Pulley wheel had come loose and was sitting forward against the power steering ram. There was also a small amount of oil the size of 2 10p pieces, but this didn't get any bigger. The Crank bolt was in place but loose and the belts were out of line.
I had the bolt retightened and some new belts put on at a cost of £242 by a Corvette specialist who assured me everything was ok and there was nothing to worry about. Coming home yesterday from picking it up it did the exact same thing!! It happens while accelerating.
The only thing I can think of is that the thread inside the crank is knackered, but shouldnt that have been an easy spot, if its not that.......any ideas?
The cars slightly modified with headers, full zorst, cams and a Corvette Concepts air intake.
Thanks in advance.
Nath (Depressed as theres a Corvette sitting on my drive I can't enjoy)
I've had my C5 now for about a month and done over 1000 miles of trouble free motoring
. That was until last week. Basically while driving I heard a bizarre noise. I stopped and noticed the Crank Pulley wheel had come loose and was sitting forward against the power steering ram. There was also a small amount of oil the size of 2 10p pieces, but this didn't get any bigger. The Crank bolt was in place but loose and the belts were out of line. I had the bolt retightened and some new belts put on at a cost of £242 by a Corvette specialist who assured me everything was ok and there was nothing to worry about. Coming home yesterday from picking it up it did the exact same thing!! It happens while accelerating.
The only thing I can think of is that the thread inside the crank is knackered, but shouldnt that have been an easy spot, if its not that.......any ideas?
The cars slightly modified with headers, full zorst, cams and a Corvette Concepts air intake.
Thanks in advance.
Nath (Depressed as theres a Corvette sitting on my drive I can't enjoy)
Err,
You can't have the pulley bolt retightened, it's torque to yeld so must be replaced with a new bolt. A specialist should have invoiced you for a new bolt, if he hasn't then ask him to do the job again as your bolt will be knackered.
The correct procedure is to tighten the damper down using a threaded bar(stud) and a nut plus a massive amount of torque. This locates the pulley in the correct position relative to the nose of the crank. Then you fit a brand new bolt torqued to a much lesser setting followed by an angular setting. new bolts have a thread sealant on them.
If you email me your number I'll give you a call. Your crank shouldn't have damaged threads unless the pulley's been pulled on with a bolt instead of a stud. Using a bolt can strip the threads in the crank. I use proper GM tooling for this work and it helps make life easier. The vette has fine balancing on the pulley so it should have been replaced in the original position but that may not be possible now unless there were any marks to help.
Boosted.
>> Edited by Boosted LS1 on Sunday 12th December 21:29
You can't have the pulley bolt retightened, it's torque to yeld so must be replaced with a new bolt. A specialist should have invoiced you for a new bolt, if he hasn't then ask him to do the job again as your bolt will be knackered.
The correct procedure is to tighten the damper down using a threaded bar(stud) and a nut plus a massive amount of torque. This locates the pulley in the correct position relative to the nose of the crank. Then you fit a brand new bolt torqued to a much lesser setting followed by an angular setting. new bolts have a thread sealant on them.
If you email me your number I'll give you a call. Your crank shouldn't have damaged threads unless the pulley's been pulled on with a bolt instead of a stud. Using a bolt can strip the threads in the crank. I use proper GM tooling for this work and it helps make life easier. The vette has fine balancing on the pulley so it should have been replaced in the original position but that may not be possible now unless there were any marks to help.
Boosted.
>> Edited by Boosted LS1 on Sunday 12th December 21:29
Latest update is...
I spoke to the garage who did the work and after some investigation by them (wish they had done this in the 1st place) apparently if you tune the engine the stock pulleys will come off (quite common apparently). They have said I need a lightened pulley apparently which will cure this fault.
They didnt fit a new bolt, said it didnt need it! Also when I asked if they would be fitting the lightened pulley for free as they didnt do the job properly he flatly refused which I thought was rude. He didnt do the job properly so therefore he should be liable for it?
He has spoken to API I think??? for a pulley, they have recommended that the crank is measured so a pulley can be made specifically for my car. Fitting the new pulley and measuring the crank will have to be done by removing the steering ram and rack etc.
If it does need the rack etc removing I can understand paying for that labour but I would at least expect the 3 hours he charged me to 'tighten' the bolt to be refunded, but clearly he is not willing to do this.
Am I asking too much?? Is 3 hours a long time to not tighten a bolt properly?
I spoke to the garage who did the work and after some investigation by them (wish they had done this in the 1st place) apparently if you tune the engine the stock pulleys will come off (quite common apparently). They have said I need a lightened pulley apparently which will cure this fault.
They didnt fit a new bolt, said it didnt need it! Also when I asked if they would be fitting the lightened pulley for free as they didnt do the job properly he flatly refused which I thought was rude. He didnt do the job properly so therefore he should be liable for it?
He has spoken to API I think??? for a pulley, they have recommended that the crank is measured so a pulley can be made specifically for my car. Fitting the new pulley and measuring the crank will have to be done by removing the steering ram and rack etc.
If it does need the rack etc removing I can understand paying for that labour but I would at least expect the 3 hours he charged me to 'tighten' the bolt to be refunded, but clearly he is not willing to do this.
Am I asking too much?? Is 3 hours a long time to not tighten a bolt properly?
This may help you.
GM use a studded bar to locate the pulley on the shaft. Use a torque wrench set at 240 lbs/ft to pull the pulley down. It will be an interferance fit on the shaft. When the bar 'clicks' remove the stud (or old pulley bolt if you used that, then look in at the end of the crank. The crank should be sitting 'below' or recessed in the pulley by 2.4- 4.48 mm. If it isn't then repeat the tightening process. Once it's snugged up in the correct place you should fit an unstretched, new bolt. Never use the old bolt as its been stretched beyond it's yield threshold. The new bolt is supplied pre-coated with a loctite compound on it. Tighten down to 37 lbs/ft and then add another 120 degrees. The loctite will then set hard, job done
Oh, I lock the flywheel up by removing the starter motor and bolting up a GM locking bracket.
Boosted.
GM use a studded bar to locate the pulley on the shaft. Use a torque wrench set at 240 lbs/ft to pull the pulley down. It will be an interferance fit on the shaft. When the bar 'clicks' remove the stud (or old pulley bolt if you used that, then look in at the end of the crank. The crank should be sitting 'below' or recessed in the pulley by 2.4- 4.48 mm. If it isn't then repeat the tightening process. Once it's snugged up in the correct place you should fit an unstretched, new bolt. Never use the old bolt as its been stretched beyond it's yield threshold. The new bolt is supplied pre-coated with a loctite compound on it. Tighten down to 37 lbs/ft and then add another 120 degrees. The loctite will then set hard, job done
Oh, I lock the flywheel up by removing the starter motor and bolting up a GM locking bracket.
Boosted.
Zr1cliff said:
Hope you sort your car out nathan,sounds like one of those annoying jobs.
BoostedLS1,ime refitting my front cover today will i have to fit a new bolt when i put the HB pulley back on?,or will i get away with loctite on the thread.
Thanks.
Always use a new bolt, the old one will be stretched. I wouldn't take a chance with this, it's not worth it as Nathan can explain. Use the proper torque settings followed by the angle setting. You will need a long bar for the leverage and a method to lock up the engine.
Boosted.
Still having a bit of a nightmare to be honest. They still dont want to admit they didnt do it properly.
Spoke to them again today as I had the car delivered up there yesterday. I asked what torque figure was used to tighten the original bolt up they used, said he recons about 120ftlb? I asked how come he didnt know for sure, his answer was because he didnt use a torque wrench...comforting. This is why it came off, plus with the fact he used the original bolt.
He has ordered an ATI pulley for it so hopefully he will fit it properly but I'm having doubts. Just got to hope that it arrives before Xmas!
Spoke to them again today as I had the car delivered up there yesterday. I asked what torque figure was used to tighten the original bolt up they used, said he recons about 120ftlb? I asked how come he didnt know for sure, his answer was because he didnt use a torque wrench...comforting. This is why it came off, plus with the fact he used the original bolt.
He has ordered an ATI pulley for it so hopefully he will fit it properly but I'm having doubts. Just got to hope that it arrives before Xmas!
Nath V said:
Still having a bit of a nightmare to be honest. They still dont want to admit they didnt do it properly.
Spoke to them again today as I had the car delivered up there yesterday. I asked what torque figure was used to tighten the original bolt up they used, said he recons about 120ftlb? I asked how come he didnt know for sure, his answer was because he didnt use a torque wrench...comforting. This is why it came off, plus with the fact he used the original bolt.
Not being picky but how do you know they will do it correctly this time around? I'd insist on being there while they do it then you will be happier. To get 240 lbs/ft takes a lot of leverage, tiz quite hard to do!
boosted.
Just noticed this thread, so I'll add my thoughts....
I think the correct tightening is actually 37lbft, then 180deg
but as stated, it is in the order of 240lbft, which is a huge amount.
Given your pulley has already come off, the crank nose is probably damaged so trying to simply refit the pulley is a bit silly, as it will no longer be the tight fit it should be, and you would expect it to come apart again..
Ive heard talk of this bolt being a TTY, but Im not sure myself. I would have thought if you re-fit it with blue loctite, that should be fine. But general concensus is it must be replaced. its not an expensive item anyway.
Never use a bolt to fit the pulley, as already stated, it will destroy the threads in the crank nose, leaving you with a major problem.
Heres my solution, assuming the crank nose isnt badly damaged, or indeed the pulley or crank pulley bolt threads. If the pully is now a loose fit on the crankshaft, get a new one. If it now requires effort to install, below suggestion should work IMO.
Get a crank Pinning kit. This basically secures the pulley agaisnt rotation in the same way a keyway would. It can be done in car with the right tools would. This needs to be done on cars with a supercharger, as the increase loads it places on the pulley whcih is normally only a press fit, would cause problems.
I could probably get you a crank pinning kit and supply a new bolt, but being so close to Xmas, not sure how soon. Mail me if you are really stuck, I do have a crank pinning kit here now, but it was for myself, so Id be reluctant to sell, not sure about the pulley though. I have a LS1 Camaro pulley here, but AFAIK the Vette drive accessories sit closer to the engine, so it would not be the same.
I have a guy in the US that could probably get one, but sometimes they are sooo slow.
Unless Mike/Boosted LS1 can help with parts ??
Do a search yourself on LS1tech, or the C5 forum. Here are a few links.
www.ls1tech.com/forums/showthread.php?t=242309&highlight=pinning
http://forums.corvetteforum.com/showthread.php?t=969547&highlight=pinning
http://forums.corvetteforum.com/showthread.php?t=968244&highlight=pinning
I think the correct tightening is actually 37lbft, then 180deg
but as stated, it is in the order of 240lbft, which is a huge amount.
Given your pulley has already come off, the crank nose is probably damaged so trying to simply refit the pulley is a bit silly, as it will no longer be the tight fit it should be, and you would expect it to come apart again..
Ive heard talk of this bolt being a TTY, but Im not sure myself. I would have thought if you re-fit it with blue loctite, that should be fine. But general concensus is it must be replaced. its not an expensive item anyway.
Never use a bolt to fit the pulley, as already stated, it will destroy the threads in the crank nose, leaving you with a major problem.
Heres my solution, assuming the crank nose isnt badly damaged, or indeed the pulley or crank pulley bolt threads. If the pully is now a loose fit on the crankshaft, get a new one. If it now requires effort to install, below suggestion should work IMO.
Get a crank Pinning kit. This basically secures the pulley agaisnt rotation in the same way a keyway would. It can be done in car with the right tools would. This needs to be done on cars with a supercharger, as the increase loads it places on the pulley whcih is normally only a press fit, would cause problems.
I could probably get you a crank pinning kit and supply a new bolt, but being so close to Xmas, not sure how soon. Mail me if you are really stuck, I do have a crank pinning kit here now, but it was for myself, so Id be reluctant to sell, not sure about the pulley though. I have a LS1 Camaro pulley here, but AFAIK the Vette drive accessories sit closer to the engine, so it would not be the same.
I have a guy in the US that could probably get one, but sometimes they are sooo slow.
Unless Mike/Boosted LS1 can help with parts ??
Do a search yourself on LS1tech, or the C5 forum. Here are a few links.
www.ls1tech.com/forums/showthread.php?t=242309&highlight=pinning
http://forums.corvetteforum.com/showthread.php?t=969547&highlight=pinning
http://forums.corvetteforum.com/showthread.php?t=968244&highlight=pinning
Thanks very much for the info, the cars at the garage now and they have ordered an ARP bolt kit last Weds, however he is going to use the original pulley.
I've asked them to check the snout and pulley for any signs of wear when its off the car and let me know. However I am very tempted with the pining so I'll drop you a email about it if it comes off again, fingers crossed it wont though....
To be honest I dont trust him now and I would like to be able to go watch and make sure he does a proper job but I dont think I'm going to be able too.
I've asked them to check the snout and pulley for any signs of wear when its off the car and let me know. However I am very tempted with the pining so I'll drop you a email about it if it comes off again, fingers crossed it wont though....
To be honest I dont trust him now and I would like to be able to go watch and make sure he does a proper job but I dont think I'm going to be able too.
I wasnt aware there was an ARP bolt available for this, nor can I see any necessity for such a thing.
It is basically just an M16 bolt, with a large mating face ( ie big washer attached )
It does seem odd though, that it is a rather common problem. Especially when you try to unbolt one, and see how tight it is to get undone, and then try to pull the pulley off. They are both damn tight.
It is basically just an M16 bolt, with a large mating face ( ie big washer attached )
It does seem odd though, that it is a rather common problem. Especially when you try to unbolt one, and see how tight it is to get undone, and then try to pull the pulley off. They are both damn tight.
Nath V said:
Thanks very much for the info, the cars at the garage now and they have ordered an ARP bolt kit last Weds, however he is going to use the original pulley.
I've asked them to check the snout and pulley for any signs of wear when its off the car and let me know. However I am very tempted with the pining so I'll drop you a email about it if it comes off again, fingers crossed it wont though....
To be honest I dont trust him now and I would like to be able to go watch and make sure he does a proper job but I dont think I'm going to be able too.
Then ask him for a guarantee that it's been torqued to factory specs and with a new bolt. He should be able to give you that reassurance otherwise it's a waste of your time and money. A monkey may be doing it for all you know. It isn't hard to do with a long bar and an electronic torque angle meter which they should have if they are vette specialists.
I don't know what Stevie's pinning kit is like but there is no protruding flange on a vette pulley to drill through. To fit a dowel you would have to drill thorough the outside diameter first in order to get to the inner diameter. Stevie, comments?
Boosted.
Look at my links above Mike. It can be done in situ, although steering rack needs moved.
Its basically a 1/4" diameter hole drilled lengthwise into the joint between crank/pulley. You then insert the 'pin' The 'pin' effectively becomes a keyway if you get the drift. Not a dowel, as I think you are picturing.
Its basically a 1/4" diameter hole drilled lengthwise into the joint between crank/pulley. You then insert the 'pin' The 'pin' effectively becomes a keyway if you get the drift. Not a dowel, as I think you are picturing.
Got the picture now Stevie, thanks for that. I was imagining a dowel type configuration and couldn't see how that was possible, doh!
Funny thing is I once read that woodruff keys only locate a pully in a certain position and that it's the interference fit which keeps them located tightly on the shaft. Maybe it's a bit of both. Still, pinning or keys must help quite a lot if not there would be no use for them. I can't imagine a pulley moving if a big enough pin has been fitted.
Is it hard to do the drilling?
Boosted.
Funny thing is I once read that woodruff keys only locate a pully in a certain position and that it's the interference fit which keeps them located tightly on the shaft. Maybe it's a bit of both. Still, pinning or keys must help quite a lot if not there would be no use for them. I can't imagine a pulley moving if a big enough pin has been fitted.
Is it hard to do the drilling?
Boosted.
I havent actually done it yet myself, but apparently its easy enough. Until I seen the kit and a few pics myself I had always pictured a dowel arrangement too.
Its pretty much a necessity for a blown application, given the extra loads put on the crank pulley.
Obviously key-ing the crank isnt really an option, and would even be difficult with the crank out of the car.
I would say that in this case where both crank and pulley have been damaged, it would be very silly not to pin it. You can replace the pulley with a new undamaged one, but replacing the crank isnt so easy. At least once pinned, there will be no rotating forces from the pulley trying to undo the bolt. The bolt does simply become a retainer, as it would with most other engines. I cant figure why GM didnt key the pulley in the first palace. It seems daft not to.
Its pretty much a necessity for a blown application, given the extra loads put on the crank pulley.
Obviously key-ing the crank isnt really an option, and would even be difficult with the crank out of the car.
I would say that in this case where both crank and pulley have been damaged, it would be very silly not to pin it. You can replace the pulley with a new undamaged one, but replacing the crank isnt so easy. At least once pinned, there will be no rotating forces from the pulley trying to undo the bolt. The bolt does simply become a retainer, as it would with most other engines. I cant figure why GM didnt key the pulley in the first palace. It seems daft not to.
, garage said its going to take a couple of days to fit the bolt due to removing the steering ram etc etc. 
...smashing!!stevieturbo said:
I cant figure why GM didnt key the pulley in the first palace. It seems daft not to.
Which palace is that?
Well, I guess they are relying on the interference fit which should be sufficient. The pulley doesn't need to be referenced for timing or anything else so it's position isn't important. From what I've heard thus far it seems that some folks just ain't torquing them up the way GM do at the plant. This situation seems fairly common with the tvr's as well. Happy Christmas Stevie.
Boosted.
Just looked at a new bolt the other day. It was mentioned both here and on LS1Tech, that they come pre-coated with Loctite.
Not really sure why people think this. The washer section of the bolt does have a read coating on it, but the threads are totally dry. So IMO there is nothing to prevent it loosening, apart from the fact its tightened so much.
I would think putting some blue loctite threadlock on it would help this situation loads.
Not really sure why people think this. The washer section of the bolt does have a read coating on it, but the threads are totally dry. So IMO there is nothing to prevent it loosening, apart from the fact its tightened so much.
I would think putting some blue loctite threadlock on it would help this situation loads.
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