Brake Master Cylinder — Removal and Installation (BMW 3 Series E21)

Removal

Use a syringe to remove some of the brake fluid from the hydraulic reservoir.

Disconnect the flexible hose of the clutch hydraulic drive from the reservoir and plug the holes of the hose and the reservoir.

On the 323i model, remove the fuel injection system mixture regulator.

Loosen the nuts securing the master cylinder to the vacuum booster, as well as the nuts securing the cylinder bracket to the wing splash guard.

Remove the cylinder bracket. Disconnect the lines from the cylinder and cover the holes at the lines and at the master cylinder to prevent fluid leakage and dust and dirt from getting in.

Remove the master cylinder.

Installation

Check the condition of the rubber ring that ensures the tightness of the connection between the master cylinder and the vacuum booster, and replace it if necessary.

Install the master cylinder and its mounting bracket to the wing splash guard.

Connect the lines to the master cylinder and tighten the cylinder mounting nuts.

Connect the flexible clutch hydraulic hose to the reservoir.

Bleed the brake system to remove air from it.

(The text is based on materials from the website «BMWman»)