Crank pulley torque

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thetim

Well-Known Member
Posts
379
The 300tdi crank pulley should be torqued to 80Nm and then another 90 degrees.
I don't have a crank immobilising tool, so getting 90 degrees is a bit of a challenge. I've gone instead for "as tight as humanly possible" which by my torque wrench is 190Nm. That's a bit below the standard torque for a M18 bolt, which I think this is (27mm head) but any more and I think I'll give myself a hernia! Tight enough?
 
Perhaps someone lives near you who has a crank locking tool.

Or you can get someone to stand on the brakes and have the vehicle in gear while you tighten the bolt?

Cheers
 
She's in gear and the drive's on a slope, so while the drivetrain is winding up a bit, it's my physical limits that are hampering me! My torque wrench is about 24" long - much longer and it would hit the ground beneath. I guess I could use a breaker bar and cut a piece of scaffolding bar to slip over it and maximise its length. My query really is, given that all it's doing is holding the fanbelt pulley in place and coping with the torsional vibrations coming through the crankshaft, does it really need to be tightened more than the max capacity of a six foot man with a two foot bar?
 
thetim said:
The 300tdi crank pulley should be torqued to 80Nm and then another 90 degrees.
I don't have a crank immobilising tool, so getting 90 degrees is a bit of a challenge. I've gone instead for "as tight as humanly possible" which by my torque wrench is 190Nm. That's a bit below the standard torque for a M18 bolt, which I think this is (27mm head) but any more and I think I'll give myself a hernia! Tight enough?
Click to expand...
use a bar or an impact gun and hopefully you used loctite on the threads
 
jamesmartin said:
use a bar or an impact gun and hopefully you used loctite on the threads
Click to expand...
My impact gun is a basic one with no torque control; I'd be nervous that I was going to rip the head off the bolt! More pertinently, I don't think I can get a gun on it without removing the rad :-(
I'll try coming up with a longer bar to get a bit more torque on it.
 
Did you happen to mark the bolt with a paint pen when it was tightened to 80Nm? so you at least know how much further you have turned it?

Cheers
 
neilly said:
Did you happen to mark the bolt with a paint pen when it was tightened to 80Nm? so you at least know how much further you have turned it?

Cheers
Click to expand...
No :-(
I've probably managed about 45 degrees or so.
The equivalent 200tdi torque is 330Nm though, so I'm only about 2/3 of the way to that point.
 
thetim said:
No :-(
I've probably managed about 45 degrees or so.
The equivalent 200tdi torque is 330Nm though, so I'm only about 2/3 of the way to that point.
Click to expand...

You can buy the crank tool for about £35, Personally I think it is one of thoes things where not torquing it correctly could come back and bite you on the derriere.
When tightening mine before i got the locking tool, I would walk mine up a 20 degree drive when in gear. So I got someone to stand on the brakes.
Cheers
 
thetim said:
My impact gun is a basic one with no torque control; I'd be nervous that I was going to rip the head off the bolt! More pertinently, I don't think I can get a gun on it without removing the rad :-(
I'll try coming up with a longer bar to get a bit more torque on it.
Click to expand...
youll not rip that bolt head off youll ,not bust it with a 6ft bar if you could lock engine enough,just get it very tight
 
OK, a longer bar got me to 210Nm. I think I might have more scope if I locked the crank, but I'd be quite surprised if it came loose any time soon. If it does, I'll obviously report back and hopefully save anyone else from a similar fate.

(whoops - posted before refreshing browser). I should be able to laser cut a locking plate for a fiver or so even if I don't buy the tool. The right bolt hole positions, plus a 1/2" square drive, in some 10mm plate ought to do the job. If I have to run it in the mean time, I'll check the torque afterwards.
 
thetim said:
She's in gear and the drive's on a slope, so while the drivetrain is winding up a bit, it's my physical limits that are hampering me! My torque wrench is about 24" long - much longer and it would hit the ground beneath. I guess I could use a breaker bar and cut a piece of scaffolding bar to slip over it and maximise its length. My query really is, given that all it's doing is holding the fanbelt pulley in place and coping with the torsional vibrations coming through the crankshaft, does it really need to be tightened more than the max capacity of a six foot man with a two foot bar?
Click to expand...
Are you trying to do it from underneath? I normally do it from the top.
 
Thankyou all. I'm in Derby. I'm working from below - the perils of a cab-forward layout means there's limited room over it to swing a bar.
 
On my 200tdi I found a bolt that slipped in through the wading plug hole, ground the tip so it was a good fit in the flywheel groove, then wrapped tape around it so it would stay pushed in. Worked fine but I have only used it once, needed a 4ft bar on my 3/4 drive to get it tightened right up, dont think i would have had any hope if i had to wind up transmission etc
 
Flossie said:
101?
Click to expand...
Oddball hybrid (the truck, not Flossie)

Swimtruck (9).JPG

Locking through the wading plug is interesting. Locking forces shouldn't be too crazy at that diameter.
 
Last edited:
thetim said:
Oddball hybrid (the truck, not Flossie)

View attachment 163693

Locking through the wading plug is interesting. Locking forces shouldn't be too crazy at that diameter.
Click to expand...
No no, don't lock the crank there for bolt undoing or tightening, it'll snap it.
It's just to hold it in the correct position so you can get the belt on without it moving.
 
Flossie said:
No no, don't lock the crank there for bolt undoing or tightening, it'll snap it.
It's just to hold it in the correct position so you can get the belt on without it moving.
Click to expand...
I know that's what it's intended for, but it's clearly working for Kev, which makes sense when you consider that the OD of the flywheel is probably three or four times the bolt circle diameter of the crank pulley locking bolts, and hence the force required to react the locking torque will be three or four times less. As long as the bolt has a couple of flats on it to make it a good fit in the slot, there shouldn't be anything seeing unduly high stresses.

Does anyone know the bolt circle diameter for the crank pulley removal bolts? I could draw up a locking tool and get it into my next order of laser cut bits. I know I could buy one, but getting one cut would cost less as well as bringing a sense of achievement :)
 
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