W123 whining sound under load

[Jerry_Mullen]

Does anybody have any ideas on what's going on here? The car is an '85 300D-T, mileage is 230K. When driving there is this whining (squeeling) sound that to me sounds like it's coming from the transmission. When the car is driving under load at around 2500RPM (greater than 40mph) the whining starts, it's not real loud but is annoying! It's not the engine or turbo because I can rev to any speed and not hear it when out of gear standing still. If I slip the car into neutral during the whining while driving, the sound stops. The sound mostly goes away once I have traveled 20 or so miles but not totally. The transmission is not slipping and shifts correctly. I also tried standing on the brakes (when stopped) and pressing down on the acellerator but don't hear the noise.

I'm sure that I am not the first one to have this problem but can't find anything in the archives.

Thanks

[Jerry_Mullen]

The squeeling sound is very much like a slipping V-belt.