Cannot Figure It Out. Whirling Noise

[italiano]

VEHICLE 2000 540I 6 Speed 106,000 miles


Ok so here is the deal that 2 mechanics cannot figure out after a large time spent on the car. SO PLEASE maybe someone has ideas because I don't. When the car is cold if i let it sit for a day or so..starts up fine and sounds good. After the vehicle heats up after about 5 minutes of driving a loud whirling sound comes. This is not a quiet whirling sound, its extremely loud and causes the car to rock back and forth. The wierd thing is the sound last for about 10 minutes then will go away, but as soon as your turn the car off and start it back up the sound will immediately come back. The mechanics listened to the idler pullies and cannot pinpoint where the noise is coming from. This is so wierd. The mechanic looked for the diagram to see if the belt was on the wrong way but couldn't find one so I am going to search to possibly see if the belt is on the wrong way but it doesn't make sense, why this is happening. PLEASE GIVE YOU INPUTS.

[Trevize]

the car rocks back and forth? Front to back? or side to side?

when the car is moving? or at idle? or both?

is it a shimmy vibration type? or a rock the boat thing?

Is the rock caused by noise vibration?

Sounds like a good puzzler for the car guys!

[italiano]

it rocks side to side as a vibration type thing. Nobody can figure this out and it's driving me nuts cuz the sound is no small sounds it's a harsh squealing

[redmansioner]

Where is the noise come from?Is it under your BMW cargo liner?Check out the strut if it is okay or maybe some transmission related problems.