Hey was this the timing belt and tensioner in the end?This is a chronic problem with the 825i I believe. I tightened my belt and the startup squeal stopped, but a separate chirping started after it warmed up. I took it to the dealer and they replaced the water pump, alternator and belt. The same thing has started happening again. I am going to let the new belt break in for about 20 hours and then tighten it. If that doesn't work, back to the dealer again.