One problem related to timing tensioner has been reported for the 2008 BMW X5. The most recently reported issues are listed below.
I was driving about 20 mph and all of the sudden I heard a snap noise and steering wheel became hard to move, I managed to park the car safely and turns out the bolt that holds the tensioner pulley broke off. The repair is thousands of dollars, I almost had an accident and because I was only doing 20 mph I managed to avoid an accident and others safety. Imagine if I was on the highway doing 70 mph. I would like BMW to pay for my repair and make it doesn't happen anymore to me or anyone else.