ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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This is going to seem like a silly question but I figured I best ask! As some of you know I have changed the crankshaft seal on my W124 250D, with the OM602 engine. When I undid the bolt I used the starter motor trick to undo it, as holding the car in gear with the handbrake on wasn't enough to stop the engine turning over. I've refitted it but again I was unable to use my breaker bar for the aforementioned reasons. Thus I used my Kielder rattle gun. Going by the car wheel nuts it can tighten to around 100-120Nm on a 17mm bolt if it's rattle for long enough. I am aware that the torque does up up for socket sizes and being 27mm I'm hoping it went up quite a bit. Using my torque wrench I know the bolt is done up to at least 150Nm, but again the engine/car turns after that despite having it in gear with the handbrake on. I'm also worried about having 300NM of force going through the clutch and drivetrain damaging things ; I've heard about this before with tightening things, but is it valid? One way around it is to get a flywheel lock. But they are hard to come by and tend to be £50-60. These use two bolts from the sump and slot into the flywheel via a small aperture in the bottom of the sump.   I've debated a screwdriver being used but I'm worried with that amount of torque it will snap, leaving me with a bigger problem (swarf in the bellhousing). I've never heard of a crank bolt being that tight previously; normally figures of 90-100Nm seem more normal. My question to you is bar buying the tool what else do you suggest? Am I right to be worried about damage to the drivetrain if I get a friend to stamp on the brake pedal as I tighten the crank bolt? I've previously used a screwdriver but never for things this tight. Part of me wants to think it is fine now (it's been fine in the workshop) but taking it to France has me wanting to eliminate potential issues for the trip. That and the oil pump is driven off the crank. |
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Last Edit: May 8, 2018 10:08:09 GMT by ChasR
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stealthstylz
Club Retro Rides Member
Posts: 14,829
Club RR Member Number: 174
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Get the tool.
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I was about to suggest a flywheel locking tool, but you've already mentioned it, just buy it, when my engine was out i just used a crowbar braced between the floor and a tooth to lock it in place, but I'm basically a massive traveller lol.
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^^ not traveller, damn PC spellcheck lol
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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Well, I've looked around for the tool. Laser wanted £120 for their tool (No. is 4706 for those wondering) and I found a BMBC/Satra version on eBay DE for £45 delivered.
I am telling myself that the two M6 x 90mm bolts will be enough to not break under 300Nm! We'll see if I am right! But then again it is the factory tool.
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I had similar issues with the crank bolt on my Audi i5. At the time I managed to borrow the proper tools from the local dealer - a crank locking tool, and a torque multiplier. Unfortunately I neglected to keep in touch with them, and wasn't anywhere near when they disposed of them some years back.
Similar warnings applied though - the transmission isn't up to the job of dealing with that level of torque, so sticking it in gear and having someone press the brake isn't recommended. I suspect the chap who'd done my water pump the previous year had just done something like that, or done it up with a rattle gun, although it ran fine it came apart quite easily when it was time to remove the engine.
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fulvia1436
Club Retro Rides Member
Finally started a thread for my Fulvia life
Posts: 341 
Club RR Member Number: 63
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Red Loctite. Don't put 300nm through your crank journals, let alone your transmission.
I have no experience of these engines, but it does seem absurd to torque a crank bolt to that figure. It only holds the pulley on, no?
Interested to hear other views.
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'59 Austin A40, '59 VW Beetle, '63 Mk1 Cortina, '57 Austin Gypsy, '68 Fiat 850 Coupe, '68 Alfa Duetto Spider, '72 Lancia Fulvia 1.3S, '73 Lancia 2000 Sedan ie., '72 Lancia 2000 Sedan, '67 Lancia Fulvia 1.3, '83 VW Passat GL5 Estate, '81 Volvo 245 Estate, '85 Lancia Thema 8V Turbo Estate, '99 Lancia Kappa 20V Turbo Estate, '00 VW Sharan VR6, '06 Fiat Multipla 1.9 JTD, '10 Fiat Multipla 1.9 JTD, '66 Lancia Fulvia 1.3
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On the Audi i5, the front crank pulley also has a heavy harmonic damper, presumably to smooth out the effect of the odd number of cylinders. I am no expert but that seemed to be the main reason that quattro gurus used to emphasise the need for the high torque.
I've got a bottle of a very strong Loctite (220? something like that) which I bought in error and now has "No! No! Not this bottle!" written across it in big letters, as I might like to undo the crank bolt at some point in the future. Quite why I've kept it is another matter.
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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Last Edit: May 9, 2018 18:03:03 GMT by ChasR
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One of the reasons the bolt torque is so high (on the Audi I5 at least) is that they don't have proper keys/keyways and rely on the clamping force produced by the very tight bolt to hold everything exactly where it should be. Not doing the bolt up tight enough can cause serious mayhem.
The Audi I5 (TDI anyway) requires a 200Nm "seating torque" (!!) and then turn through a further 270º. That is tight.....
The Audi locking tool engages in a spline in the centre of the harmonic damper and has a plate that picks up on threaded bosses on the block. It's not unknown for the bosses to snap off - though usually because someone has though 1 or two bolts (of a possible 3 IIRC) is enough.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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May 10, 2018 10:10:23 GMT
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That locking tool sounds a little different - the one I borrowed seemed to push against the front engine mounting, but it's a long time ago. Has to be done with the engine in the car (in my coupe, anyway) because with the damper in place, the engine won't clear the front panel.
Mine's an '86 KV engine, though, which is before they had the good sense to make it possible to change the water pump and cam belt without removing the damper. On mine, the water pump is behind the timing belt rear cover which won't come off unless the pulley is removed, and the bottom section of the cover is the casting on the front of the oil pump. I am thinking that lopping 10mm or so off that casting won't affect anything and will let me get the belt off, and I'll get the dremel on the rear cover plate for access to the pump. I had a later engine in an Audi 100 which certainly had a mod like that for water pump access.
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Last Edit: May 10, 2018 10:13:55 GMT by droopsnoot
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May 10, 2018 18:49:54 GMT
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I would try to find a way to achieve that torque as the factory would not specify this just for fun. Do not worry about the 2 bolts of the locking tool. Torque = force x arm.
300Nm on a 17mm bolt means that when the flywheel has a diameter of 300mm, the bolts each face a force of 500N which roughly equals a weight of 50kg so not a problem at all. you could try to make this tool yourself
Peter
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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May 12, 2018 20:31:06 GMT
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Well, it's time for an update. I would try to find a way to achieve that torque as the factory would not specify this just for fun. Do not worry about the 2 bolts of the locking tool. Torque = force x arm. 300Nm on a 17mm bolt means that when the flywheel has a diameter of 300mm, the bolts each face a force of 500N which roughly equals a weight of 50kg so not a problem at all. you could try to make this tool yourself Peter You'll be glad to know that did. As I alluded to previously I did order a tool from eBay DE. I had to keep telling myself that 300Nm on two M6 bolts (abeit hardened) would be fine and that the tool itself would hold up! Today, the tool arrived.  Mercedes Laon Prepartions v2 (7 of 8) by Charlieboy, on Flickr Yup, those bolts are tiny! I couldn't get a crow bar in there and unlike the auto owners (mine's a manual) I had nothing to jam in flywheel as it isn't holed like the flexplates are. With that in mind I carefully removed the two lower sump bolts; they weren't in very tight at all! With that in mind I fitted in the tool, nipped them up to a similar torque (I think they are metric fine and I have stripped these in PSA cars previously for the same application) and carefully went to work, hoping not to break anything! Note the removed bolts; the replacement bolts in the kit are larger to accomodate the addition of the flywheel lock.  Mercedes Laon Prepartions v2 (6 of 8) by Charlieboy, on Flickr  Mercedes Laon Prepartions v2 (5 of 8) by Charlieboy, on Flickr With that done I then went to tighten it. As suspected it was done to 150Nm. I then set it to 220Nm. The bolt moved but not much to get to 20Nm. I then went to 320Nm, as per the manual. The bolt did turn a bit more, probably another 40 degrees or so. Finally the wrench clicked! I was awaiting the wrench to go freely as I snapped something! However, I needn't have worried for obvious reasons! I don't know why but to my mind the engine *may* actually be running a little quieter/smoother at idle since I torqued it correctly, and ever since I have owned the car! It used to have a slight vibration at idle after doing the engine mounts (it shook horribly prior to that!). That mild vibration has now gone! Cheers for the encouragement folks and the wise words! On the other hand at least I have a tool that seems to be a rarity over in the UK! Should an RRer want to borrow it let me know! |
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May 12, 2018 20:55:24 GMT
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good to hear its done and went well. It should give you a relaxed feeling when driving the car and knowing its done well.
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