Pressure regulator — removal and installation (BMW 3 Series E21)

Removal

Remove the brake fluid from the hydraulic reservoir using a syringe.

Disconnect the lines from the pressure regulator.

Loosen the bolts securing the pressure regulator to the front left wing mudguard bracket and remove the regulator.

Installation

Replace and secure the pressure regulator.

Connect the lines to the pressure regulator and bleed the brake system to remove air from it.

Checking the performance of the pressure regulator

Attach a high pressure gauge to the brake bleed nipple of one of the front wheel brake mechanisms.

Loosen the bolt securing the telescopic strut to the front suspension arm.

Attach another high pressure gauge to the brake bleed nipple of one of the rear wheel brake mechanisms.

Remove air from the pressure gauges.

Press the brake pedal fully at least five times.

Move the brake pedal to a position where the pressure in the line is 25 kg/cm², and both pressure gauges should show the same pressure. As the brake pedal is moved further, the pressure in the wheel cylinder of the rear wheel brake mechanism should increase more slowly than in the wheel cylinder of the front wheel brake mechanism.

When installing a new pressure regulator, pay attention to its digital marking, for example, 25/8, where the number "25" is the digital index of the regulator, and the number "8" indicates that the diameter of the regulator piston is 18 mm.