I have very loud howling sound coming from the rear of my 1992 MB 400E. The sound doesn't begin until I have been driving for about 5 minutes, and whatever is making the sound has heated up. The sound goes away when I take left turns and when I hit the brakes. It is especially loud when I get off the highway and am traveling at slower speeds. A local mechanic told me the bearings looked fine, and the brakes were also fine. This sound is unbearable while I drive and it is very stressful to not know what is wrong. Any help would be greatly appreciated.

 

the noise you here is your sunroof motor struggling when you open it all the way to the limits it some times does not stop