Hi All,
I have 98 ML 320 with 58K miles that has recently developed a bad whining noise from the drivetrain somewhere. I ruled out engine related issues because it is independent of engine speed (rev in park, it aint there!). I "hope" and think it is not the tranny because the shifts are still crisp, no delays, no clunks.

The whine seems to be in tune with the speed of the truck/wheels and increases/decreases in pitch and frequency with my speed. The odd part is, after a certain speed or revolutions of whatever is down there in the nether regions it abruptly stops. My guess (I am trying, so bear with me) is that the diff fluid is either low or thick due to the fact that it has not been above freezing in over a week. Hence after a certain number of revolutions it finally warms up and is thrown all over the diff case thus silencing the whine?

Any thoughts SURE would be appreciated as I am out of warranty and SHUTTER to think of potential damage.

TIA!

Joe Hahn, Cleveland Ohio

(by the way, I did search but either used the wrong terms or this is not covered prior)