Guys,
Take a look at this clip and listen carefully a bit into it and tell me what you think it can be.
http://www.youtube.com/watch?v=QM3Z1txcqBg
It is from a 2000 328i , but I have the exact same sound in my X5.
It happen only on cold start and last for a couple of seconds (2-3seconds), and when we shift from P to D or P to R same sound and that's it. Further into the clip. Only after the car has been resting for several hours. After that it's gone until next morning.
This is not the typical belt/tensioner problem. Not the vanos rattle, not likely to be the alternator. It is not the secondary air pump because in Europe we do not have pumps on our cars. It is maybe related to the not OEM transmission filter starving the torque converter, but why then only during cold start after resting for hours. I also have a non OEM filter after a ATF fluid change some weeks ago,
Anyone with experience around this strange sound.