Crankshaft Pulley Bolt

[nicknikolovski]

Hi guys,

Doing my timing chain shortly, just waiting on parts to arrive.

I was reading up on the Bentley service manual for the E36 (M42 section) and discovered that when they mentioned the step for refitting the M16 crank pulley bolt it should be replaced because it is a stretch bolt.

Is this true and will it make a difference?

Also has anyone actually the replaced the bolt?
Because in this procedure
http://www.esatclear.ie/~bpurcell/318istimingchain.html they don't mention this.

Any help would be appreciated, thanks

[Vladi]

The BMW Service Bulletin of the time and TIS also says that bolt _must_ be replaced, just like the flywheel bolts.
You have no difference to see. The difference between the new bolt and the old one can be a pulley and sprocket going through your radiator. The old one can last as well but there is no guarantee.
The best thing is to do what Bentley says, those bolts are meant to be like that for a calculated reason.

[b318isp]

I've never heard of anyone changing it, but it is not a bad idea. Flywheels bolts is a no brainer, but I honestly don't know why there is such high torque on the pulley bolt.

[bmwpower]

I've never heard of anyone changing it, but it is not a bad idea. Flywheels bolts is a no brainer, but I honestly don't know why there is such high torque on the pulley bolt.

That pulley has to turn both cams and a double chain setup...at high RPMs.  You think that is high, you should torque an M30...340ft-lbs.

[Jak318]

That pulley has to turn both cams and a double chain setup...at high RPMs.  You think that is high, you should torque an M30...340ft-lbs.

The only thing that bolt does is hold the pulley and balancer onto the crank shaft. The balancer is "keyed" so that it can't turn separate from the crank. All of the force from the engine turning is applied to the key not the bolt. Also the pulley turns the accessories like the A/C, PS, and the Alternator. It does not turn the cam sprockets, they are driven by the sprocket on the crank which turns the chain and that turns the cam sprockets at the equivalent RPM.

I reused my bolt only because BMA forgot to include it in my order even though I was emailed a confirmation that it would be. I have since ordered a new bolt from BMA at a cost of only $0.40 and I will replace it the next time I am working down there.

I have put over 1000 miles on it now and it has not loosened but I agree that it is a stretch bolt and should be replaced. In a pinch it should be safe to reuse for awhile, at least until you can order a new one.

I used the Bentley manual for the procedure. Here is the link for my parts list from when I did my chain a couple months ago.

http://www.r3vlimited.com/board/showthread.php?t=96062&page=2

[nicknikolovski]

thanks for all the helpful info, appreciate it.

[bmwpower]

Yea, I was referring to the crank sprocket, not pulley.  Brain fart.

So does the Bentley have all the torque values for everything?

The only thing that bolt does is hold the pulley and balancer onto the crank shaft. The balancer is "keyed" so that it can't turn separate from the crank. All of the force from the engine turning is applied to the key not the bolt. Also the pulley turns the accessories like the A/C, PS, and the Alternator. It does not turn the cam sprockets, they are driven by the sprocket on the crank which turns the chain and that turns the cam sprockets at the equivalent RPM.

I reused my bolt only because BMA forgot to include it in my order even though I was emailed a confirmation that it would be. I have since ordered a new bolt from BMA at a cost of only $0.40 and I will replace it the next time I am working down there.

I have put over 1000 miles on it now and it has not loosened but I agree that it is a stretch bolt and should be replaced. In a pinch it should be safe to reuse for awhile, at least until you can order a new one.

I used the Bentley manual for the procedure. Here is the link for my parts list from when I did my chain a couple months ago.

http://www.r3vlimited.com/board/showthread.php?t=96062&page=2