W210 Aux Water Pump Brushes Replacement

[Southern]

I posted this on Benzworld and will post it here to help anyone with a W210n aux water pump save some $.

I had a b1416 code that was related to the aux water pump. I decided to clear the last remaining code on my 98 E320.

I started by entering the REST mode and checked the voltage at the pump. It measured 12VDC so I tapped on the pump and it would randomly start. I then decided to remove the pump and take it apart to have a look. After removing the rear of the motor I saw that it was gunked-up with debris from the brushes. After looking closer it was evident that the brushes were almost completely worn. After doing some searching a new aux pump cost over $200 and I could not locate just the brushes.

I recall that my local ACE hardware sold brushes for small electric motors so I head down to have a look. I figured that I could not locate an exact match for brushes so I selected some that were a little larger. The ACE number for the brushes I purchased is 58310-F and cost $3.70 each. After bringing them home it was obvious that I need to sand them down to fit. I not only needed to sand the edges but the length was too long and need to be sanded to about 1/2" long. I also needed to clip the end cap and remove the spring.

After the necessary sanding I installed the new brushes and need to solder the wires in place. In order to reinstall the end cap assembly back into the motor it was necessary to pre-load the brushes back in the holder and have the spring hold the very end of the brushes so that it would allow me to slip the end cap over the motor shaft and clear the commutator. This was the most difficult part because if the springs allowed the brushes to move inward before they cleared the commutator it would prevent the end cap from going in all the way.

After carefully placing the end cap over the motor assembly I tapped the side of the motor to release the springs so that the brushes were in contact with the commutator. After reconnecting the aux water pump back in the car I activated the REST mode and the motor started up. I checked for the dreaded b1416 fault and it was gone. I was able to spend under $8.00 and save a $200 aux. water pump from the landfill.

I will attempt to attached some photos that I took during the process.