Signs of air in the hydraulic drive:
- increase in pedal travel, its "softness" when pressing the pedal once;
- gradual reduction of the pedal stroke with a simultaneous increase in its "rigidity" with repeated pressing of the pedal.
Before bleeding the hydraulic drive, it is necessary to identify and eliminate the cause of the depressurization.
USEFUL TIP: If bleeding the hydraulic drive is associated with the repair of one circuit and the serviceability of another circuit is known, then bleeding only the circuit being repaired is permissible.
The steps for bleeding the hydraulic drive are the same as for replacing the brake fluid, see below (see "Replacing brake fluid in the hydraulic brake drive"). The only difference is that the criterion for completing the bleeding of the working cylinder is the cessation of air bubbles coming out of the hose, and not the appearance of fresh brake fluid.
[The article is reprinted from the website chevyman]