In the process of checking out the cooling/heating system of my 1987 190DT I discovered that both electric aux fans in front of the radiator did not run. In fact they were difficult to turn by hand. I pulled them apart partly and blew out the accumulated sand/gravel from the motors. I repacked the front bearing on one and hooked it up to 12vdc. It ran! The second fan was not quite as simple or cheap...but faced with spending $150-200 on a replacment I took it to my local auto electric shop. $40 to replace the brushes and repack the bearings and I had 2 good fans!
I am constantly amazed at the rebuildability of these cars components!
Now if I could just get the rear windows to work.
Dana