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Vanagon Nut Samba Member
Joined: February 08, 2008 Posts: 10379 Location: Sunshine Coast B.C.
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Posted: Thu Apr 28, 2016 1:13 pm Post subject: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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Hi all.
I searched via title on this.
Have seen the results of the first hand and heard about it via a fellow camper
at a recent campout. We discussed why this would happen.
I believe he posted here about his adventure with that issue.
Bentley shows an entire page on tightening this bolt properly.
From the factory, I assume this wasn't an issue. Here's what he and I figured
were the main contributors to bolt backing out:
- torque value used was too low (no special tool, guess work deployed)
- bolt re-used too many times (it has a fine thread)
- crank key way and/or woodruff key worn beyond spec prior to rebuild/repair
- cross threading bolt on install
or ?
The sad part is that the average owner/wrencher probably doesn't have the
means to easily remove this bolt and retorque to be safe. I guess one just keeps
an eagle eye on their engine!
Neil. _________________ 1981 Westy DIY 15º ABA
1988 West DIY 50º ABA
VE7TBN |
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MidwestDrifter Samba Member
Joined: June 13, 2012 Posts: 769 Location: Kicking Around Australia
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Posted: Thu Apr 28, 2016 1:40 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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The key is only for initial alignment. In service the bolts clamping force and the resulting friction prevent the pulley and crank from moving respective to each other.
Unless the bolt is TTY, it can be reused. Most high load bolts only have 2-3 good pull downs until the thread is worn enough to affect the clamping load. When in doubt, get a new bolt!
Under-torquing can lead to keyway failure, bolt fatigue failure, or the bolt loosening. When in doubt get a torque wrench!
Over-torquing can cause the bolt to stretch plastically. This can result in the bolt breaking either immediately or shortly down the road.
Unless the manual specifies lubrication, bolts like this are to be installed dry! Lubrication can result in a normal torque level creating excessive clamping force, which could damage the bolt or the threads.
Its pretty unusual for these bolts to loosen over time when installed correctly. When/if they do; damage to or imbalance in the belt drive system is to be suspected. _________________ 2004 Dodge/Mercedes Sprinter (Custom Camper)
2000 Jetta TDI
1982 Diesel Westy W/ ABA I4 hybrid (Sold)
Epic Road Tripping since 08/05/12 | http://VagariesAbound.blogspot.com/
My Current Build | http://sprinter-source.com/forum/showthread.php?t=41215 |
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t3 kopf Samba Member
Joined: October 22, 2012 Posts: 1115 Location: over by 'der
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Posted: Thu Apr 28, 2016 2:03 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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I agree with all the above except the no lube part. I believe that high torque bolts like these should have the threads lightly oiled. _________________ '90 Carat w/ '95 phase 1 EJ22 OBD2 conversion |
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MidwestDrifter Samba Member
Joined: June 13, 2012 Posts: 769 Location: Kicking Around Australia
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Posted: Thu Apr 28, 2016 2:06 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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t3 kopf wrote: |
I agree with all the above except the no lube part. I believe that high torque bolts like these should have the threads lightly oiled. |
In general almost every one I have seen does specify lightly oiled (or they come packaged that way).
The only real concern is that in a few (Not vanagon) applications, the torque value is adjusted for dry threads. Lubing the bolt in this case can result in issues.
Of course I probably should have left that comment off my post, as it doesn't affect the WBX. Of course there are quite a few engine conversions floating around these days... _________________ 2004 Dodge/Mercedes Sprinter (Custom Camper)
2000 Jetta TDI
1982 Diesel Westy W/ ABA I4 hybrid (Sold)
Epic Road Tripping since 08/05/12 | http://VagariesAbound.blogspot.com/
My Current Build | http://sprinter-source.com/forum/showthread.php?t=41215 |
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Vanagon Nut Samba Member
Joined: February 08, 2008 Posts: 10379 Location: Sunshine Coast B.C.
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Posted: Fri Apr 29, 2016 12:04 am Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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Oh my. Engine conversions. I don't know why I chimed in.
Ok. For sure. I see the point on woodruff key. And thats a good point on
balance in the belt drive system. I mean it's not like the alt. bracket is ever
an issue. lol.
Since the torque value is so high, and it's tough to hold the pulley dead still
without the right tool or similar, one could easily under torque that bolt.
I'm sure the event I saw and heard about are relatively rare.
Neil. _________________ 1981 Westy DIY 15º ABA
1988 West DIY 50º ABA
VE7TBN |
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jerryherb Samba Member
Joined: October 30, 2015 Posts: 205
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Posted: Fri Dec 13, 2019 3:59 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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my main bolt came loose to the point i could remove it by hand. no damage to threads, woodruff appears worn as the pulley was banging on it. any pointers on how to get the 250lbs on the bolt WITHOUT the key no one but a specialized shop probably still has? |
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IdahoDoug Samba Member
Joined: June 12, 2010 Posts: 10251 Location: N. Idaho
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Posted: Fri Dec 13, 2019 5:32 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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What is this "key" you want to do the tightening without? _________________ 1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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dgbeatty Samba Member
Joined: October 26, 2006 Posts: 702 Location: Sacramento
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Posted: Fri Dec 13, 2019 6:54 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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They come loose primarily due to improper installation. _________________ Schau in das Buch |
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vanagonjr Samba Member
Joined: October 07, 2010 Posts: 3431 Location: Dartmouth, Mass.
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Butcher Samba Member
Joined: December 05, 2015 Posts: 1285 Location: Right Here
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Posted: Sat Dec 14, 2019 8:20 am Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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The key is a lock tool to prevent the crankshaft from moving while torquing on the bolt.
Last edited by Butcher on Sun Dec 15, 2019 9:59 am; edited 1 time in total |
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IdahoDoug Samba Member
Joined: June 12, 2010 Posts: 10251 Location: N. Idaho
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Posted: Sat Dec 14, 2019 10:44 am Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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I guess I'm not going to get an answer to my question on what key you want to do this without? Since you refer to "shop" I'm assuming you think there is some kind of shop tool (a key) to hold the pulley, etc. So I will continue into the fog of answering your question to say you can immobilize the pulley with a chain to tighten against it. _________________ 1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Sat Dec 14, 2019 10:52 am Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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I have some yacht braid polyester (this is not the cheap polypropylene rope you can get anywhere) that I tie off to some place on the engine and then wrap the crank pulley a couple of turns. While keeping tension on the free end of the rope you can apply torque to the nut and tighten down the pulley. You could probably do the same with some 3/32 or 3/16 wire rope, or you can cut up an old V-belt and use it.
If using rope, the closer you can tie off the rope to the pulley the less stretch you will get. |
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IdahoDoug Samba Member
Joined: June 12, 2010 Posts: 10251 Location: N. Idaho
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Posted: Sat Dec 14, 2019 10:54 am Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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That's a great idea. Your technique also eliminates the chance of the chain damaging the pulley. I like it - thanks. _________________ 1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Sat Dec 14, 2019 11:18 am Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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IdahoDoug wrote: |
That's a great idea. Your technique also eliminates the chance of the chain damaging the pulley. I like it - thanks. |
It can take a lot of tension so an extra set of hands can make things easier though I usually get it done by myself. I did once have a cut up V-belt for this purpose, should make up another one and have it on hand. |
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AtlasShrugged Samba Member
Joined: October 30, 2008 Posts: 1605 Location: Decatur, Ga. USA
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Posted: Sat Dec 14, 2019 12:29 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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When you need a new woodruff key for the crankshaft they are NLA from VW. Part number 070105249
BusLab has them for $2.50
https://www.buslab.com/product-p/070105249.htm |
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IdahoDoug Samba Member
Joined: June 12, 2010 Posts: 10251 Location: N. Idaho
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Posted: Sat Dec 14, 2019 3:35 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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If you could, I'd love to know the diameter of the rope as what you're using works and I'll be guessing. We're boaters and may even have some on hand. _________________ 1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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mellowslow Samba Member
Joined: July 31, 2009 Posts: 278 Location: Vacationland
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Sat Dec 14, 2019 6:22 pm Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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IdahoDoug wrote: |
If you could, I'd love to know the diameter of the rope as what you're using works and I'll be guessing. We're boaters and may even have some on hand. |
I think what I have is 3/8" but am down south for the winter and thus can not verify it. |
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djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32625 Location: Reading Pennsylvania
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jerryherb Samba Member
Joined: October 30, 2015 Posts: 205
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Posted: Sun Dec 15, 2019 10:32 am Post subject: Re: Crankshaft Pulley Bolt: Why Would It Come Loose? |
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thanks for all the replies, by mistakenly typing "key" i meant the pulley tool 3102 on bentley page 13.42 . i did order the woodruff key as mine was pretty beat up by pulley banging on it hence creating the clunking i thought was coming from the TC/tranny as in my other posts. pulley grove appears ok so i will reuse it.
does anyone own the 3102 and can post the dimensions so that maybe i can build one? i have seen the GW flexplate lock, but would rather lock the pulley side than transfer 258lbs of torque through my old engine crankshaft and the TC/plate. someone did mention the cranshaft can bend. though i find it unlikely i think the pulley lock is a better and fool proof method.
would any other pulley lock work? i will investigate the rope method if i cant find any other solution
i was considering this, which obviously would require a helper, though not sure it would fit the pulley as the holes are recessed pretty far in:
https://www.amazon.com/OTC-4754-Universal-Pulley-Holder/dp/B000Q8GVPY
Last edited by jerryherb on Sun Dec 15, 2019 10:39 am; edited 1 time in total |
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