Replacement and testing of generator and voltage regulator carbon brushes (BMW 3 Series E30)

Carbon brushes are checked as part of the vehicle maintenance schedule every 60,000 km.

Removal

Removal of carbon brushes is possible without removing the generator.

Disconnect the ground wire from the battery.

Bosch voltage regulator

Unscrew the voltage regulator with the brush holder from the back of the generator and carefully pull it out.

Replace the carbon brushes if their length is less than 5 mm, for which purpose unsolder the current leads.

Check the wear of the contact rings, and if necessary, grind and polish them.

Clean the contact surfaces and check the elasticity of the contact springs; replace if necessary.

Installation

To prevent solder from getting into the brush braid when soldering new brushes, hold the braid with tweezers.

Caution: Solder will cause the braid to become stiff and brittle and the brushes to become unusable.

The insulation should be clamped in the lugs near the soldering point.

After installation, check the ease of movement of the brushes in the brush holder.

Place and secure the voltage regulator first with one screw, then press it down and secure it completely.

Connect the ground wire to the battery.

Motorola Voltage Regulator

Removal

Unscrew the radio interference filter capacitor from the back of the generator.

Disconnect the voltage regulator connector and remove the regulator.

Installation

Insert the voltage regulator.

Note: The colors of the wires must match the colors of the contacts.

Screw on the radio interference filter capacitor.

Check and, if necessary, adjust the electrolyte level in the battery.

On six-cylinder and diesel engines: check the exhaust gas tank and empty it if necessary.