PeachParts Mercedes-Benz Forum - View Single Post

JimSmith · #2 03-22-2002, 01:51 AM

Peter,

I am not absolutely sure about the alternator in your vehicle, but the engine was the same as the later w123 300D Turbo, so I will assume the alternator was the same as the alternator that came with that car.

To answer your question, yes, the brushes are part of the voltage regulator assembly. The plug you disconnected on the back of the alternator is plugged into the voltage regulator assembly. It should have had a little wire spring clip holding the plug in place.

Anyway, the voltage regulator comes out by pushing the spring clip off the plug, unplugging the plug, and then unscrewing two screws on the "ears" of the flange on the voltage regulator. The unit then kind of rolls down and to rear, out of its openning, in the back of the alternator.

If the brushes are really small nibs, like a quarter inch long or so, they are shot. They are about an inch or more long when new.

If they are evenly worn, you only need brushes.

If they are unevenly worn you have either an electrical or mechanical imbalance in the machine and the alternator needs to be rebuilt. I would get one from FastLane that is rebuilt by Bosch. If the brushes are evenly worn, but the wear surfaces look rough and gouged, there is a problem on the copper contacts on the rotor, like a burr or other form of raised metal that is causing the gouges. Replacing the brushes in these instances will likely work for a few days, weeks or months, but once you have a mechanism that causes increased wear, changing the soft part of the wear couple will not solve the problem.

Hope this helps, Jim