Or maybe installation failure on my part… But I did install it with an impact gun and hand torqued to spec.

I was on my way back to the office after a trip up to Shaw Industries in Dalton, GA yesterday. During a stop at an exit ramp I heard a very noticeable rattling sound from the engine bay. I got out and looked; the sound was coming from around the alternator but I thought it might be the tensioner failing.

So I decided to go back to my house, drop off the CL and pick up the BMW before heading into the office. I was going to check it out later and then get into the dealer if it was the tensioner. On my way to the house I hit some road work and had to re-route. About ten miles from home my battery light and brake lights come on in the dash. I now knew what was up.

So I turned off the radio and heat and made it home without incident. When I popped the hood I found the alternator pulley laying against the PS reservoir bottle still slightly on the shaft. But the pulley locknut and the belt were no where to be found. The nut came off and the belt too; lost somewhere near Canton, GA.

I had planned on pulling the AEM pulley off soon anyway as a certain SC will be purchased in the future but I didn't plan on it this way. I called the dealer to find out about purchasing a new nut and they wanted $7 for it along with a two day wait; it would be in on Tuesday. So I went to the hardware store and picked up various sizes of metric bolts; it turns out to be an M14 fine thread. So the stock pulley is back on and everything is running as it should.

But that AEM pulley sure took a beating as shown in the pic below. There were plenty of metal shavings on the bottom cowl.

 

strange indeed.

 

ill offer a theory...can the bbelts get tighter with engine flex? if a motor mount or multiple pounts were bad could flexing of the engine under WOT put alot more tension on the belt causing the pulleys to warp and vibration rip it apart?

 

I need to tighten the PS Belt a bit cause the UR Pulley is bit noisy on cold morning. I did the hand tension test and it seems tight but still there is noise... What to do?

 

Hope everything is all right...

 

maybe a little dab of thread lock will help from further faluire.

 

Good point... Although it was never required, it did go onto the stock pulley's threads. I would reccomend it for anyone doing a swap.

 

wow thats crazy, i aint gonna mess w/ pully's

 

Are there bearings on the alternator... might want to take a look or just play with it. Sometimes odd torque on these things can cause minor irregularities... might cause headaches later on!

 

The runout with the stock pulley is fine. I will keep an eye on it just in case though. But I don't forsee any problems.

 

you also have to remember that the pulley is aluminum. I will shrink and expand with heat and cold. That why they don't really use aluminum wire in houses. Terminals would get loose after time because of the expanding and contracting of the wire. Then it would cause fires because of the loose connection causing an Arc. They use copper pretty much in all installations now a days. I'm a local 3 electrican