this won;t be of much help, but my 9yr old M50 motor in our 520i auto which used to be really creamy smooth (still is, though a but coarser now) hs become rather noisy in action....there's this very apparent mechanical purr and something like a high pitched whistle to accompany it...but then again it could be age and neglect....it sometimes has trouble firing on the first attempt too....any ideas? Cheers Kenneth