Had the identical problem with my 84 325e wich resulted in a $200 tow bill.Here's what i did.I replaced the 1 mount i had that was weak with OE wich cost a whopping $18.I then got a belt for the pulley that was exactly 1 inch shorter,and that was a whopping $11.Have run the car several times since and PRESTO! no more problems.Hope that helps. P.S Where do you run?