Bleeding the hydraulic drive of the brake system

The hydraulic brake drive is pumped to remove air that got there when filling with liquid after replacing it or after repairing the hydraulic drive units associated with its depressurization.

Signs of the presence of air in the hydraulic drive:

• increase in pedal travel «softness» with a single press on the pedal;
• a gradual decrease in pedal travel with a simultaneous increase in its «rigidity» when you press the pedal again.

Before pumping the hydraulic drive, it is necessary to find and eliminate the cause of depressurization.

Note. If the pumping of the hydraulic drive is associated with the repair of any one circuit and the serviceability of the other circuit is known, then only the repaired circuit can be pumped.

The steps for bleeding the hydraulic drive are the same as for replacing the brake fluid described in Sec. 4 «Replacement of brake fluid in hydraulic brakes and clutch release»). The only difference is that the criterion for completing the pumping of the working cylinder is the cessation of the release of air bubbles from the hose, and not the appearance of fresh brake fluid.