Member
This is horrible, I was driving down the road and I hear a crunching sound, pull over n My freaking harmonic balancer/crank pulley was loose, it destroyed my belts and my water pump pulley, I took the 8 13mm bolts and removed the crank pulley entirely, what to do now? Is my engine out of time, I know I’m gonna need another belt but the harmonic balancer looks undamaged, what should my next move be, I never would have thought that pulley would have came loose. It’s an m52 so I don’t think I need to worry about the crank sensor.
Member
Relax.
Engine cam timing does not rely on the balancer, that is all done internally and since you have a OBD2 engine the crank sensor is in the rear.
Check your balancer and pulleys for any damage, replace as needed and get new belts. Torque it all correctly and reinstall.
Jbird
second that
Member
The biggest danger is that you have damaged the crankshaft. This happened to me on a Z32. It was obvious by visual inspection that the loosened pulley had eaten up the end of the crankshaft. If I ever take one off again, I'll safety-wire it back on. I had to get another engine. I hope yours is okay.
Member
This is negated by the keyway. From what I have heard anecdotally the s52 has a higher probability of this due to crankshaft harmonics. In my first hand experience, the end of the s52/m54b30 crankshaft is ever so slightly smaller than the m52 crankshaft and the damper fits on looser as a result (same damper). I put a m54 damper on my stroker and it was a snugger fit.Originally Posted by spyderg0d
Member
Inspect the pulleys for any dents or dings, it will be off balance if there are any. You will need two new woodruf keys for the crank and a special wrench to properly torque the crank bolt.
https://www.ebay.com/itm/BMW-M20-M40...L/143203476386
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2 woodruf keys
https://www.rmeuropean.com/Products/...MFG9-V260.aspx
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You didn't say if the 6 smaller 8mm pulley bolts came loose or the big 18mm center bolt into the crankshaft came loose.
See ya later,
tony
'98 M3, '92 Dinan3, '05 R1100S BCR, '07 R1200S, Aprilia T
Member
The only effect of the engine's rotation to tighten that bolt is working against the inertia of the bolt, which is small. When a bolt is threaded in a specific direction to keep it tight (like bicycle pedals) it is so so any motion of the object being secured will be in the direction to tighten the fastener, what I was implying is the woodruff key will prevent the damper from starting to spin. These engine rely a tremendous amount of clamping force of the "Jesus Bolt" to prevent the damper from wobbling rather than having any taper.
Member
Might need to rethink that logic. Consider that the big bolt on the front pulley and the oil pump nut are both spinning in the same direction. The front pulley bolt is right-hand threaded and the oil pump nut is left-hand threaded. One would have the loosening issue with RPM deceleration and the other with RPM acceleration. I think we know which is which.
I don't think the original issue was with the big bolt, anyway, so it really doesn't matter even if I do drill and safety wire the all the oil pump nuts.
See ya later,
tony
'98 M3, '92 Dinan3, '05 R1100S BCR, '07 R1200S, Aprilia T
Member
Your logic is faulty and your understanding of simple physics is lacking. If what you profess is true and the 18mm bolt that BMW would like to have replaced and torqued to 410 lb.ft. each time it's removed then that bolt could then be installed finger tight and it would torque itself up to 410. Not gonna happen.
Member
That makes sense there is no force acting on the bolt. The key locks the pulley from rotating. The rotating engine does not act on the bolt because that pulley is not able to move. If the pulley could move then the mass of the pulley and crank could act on the bolt. There is no torque applied to the bolt other than what the installer performed on the bolt.
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Zohaibrose, we need pics!
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The fact that the damper interface with the crankshaft is non-tapered means the clamping force of the crank bolt is the only means that secures the damper. There are several accounts of the damper coming loose on track driven s52 engines, from what I surmise, it is a result of tunes increasing the rev limits and the s52 crank harmonics. The harmonic factor would mean the bolts are vibrating loose and for this reason serious racers is a $1k aftermarket mti damper. On tapered crankshafts, the circumference of the diameter is stretched as it is clamped onto the crankshaft by the bolt. This provides an additional layer of protection from the damper coming loose.
Member
no what happen to me is the 6 8mm bolts came loose, prob from being not torqued, the big Jesus bolt is still on there but the crank pulley is not. I will post pics now
Member
So, you might want to work on how you word things. The crank pulley is the main pulley not the secondary pulley bolted to it.
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