I used pulley to describe the noise but this is not a pulley problem.
I narrowed it down a bit but not enough. I went under the car today and it seems like the noise is there when rev-ing in certain condition but not need to drive it. It seems to be in the transfer case or trasmission or transmits from the back of the engine. I rev it and release it and it happens but not necessary at a certain RPMs. I have to keep changing the RPMs rapidly to get that thing to wobble and touch the metal something to get the metallic noise.
Since it is reproduceable while parked I assume it must be the torque converter or the transmission. The transfer case doesn't get any parts in motion until the transmission put something on the output shaft.
I might need to take the tranny oil pan down and see if I find something in the pan.
The noise can also come from the back of the engine, it's so hard to narrow it down. Could it be a chain? Where is the chain tensioner on n62?

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4.8is 2004 imola red
4.8is 2005 Black on Black - DINAN/2 sold
4.4 2004 X5
2003 330xi
2008 328xi - sold
4.4 2000 X5 - sold