Before removing air from the brake system, make sure that all brake drive units and their connections are tight, check, fix the fluid level in the reservoir and, if necessary, fill the reservoir to the level «MAX» brake fluid. After pumping, the liquid should be at the same level. If necessary, add liquid or drain excess with a pear. Then carefully clean the bleeder fittings from dirt and dust and remove the protective caps from them.
Put a rubber hose on the head of the fitting (pic. 6-7) to drain the liquid, and lower its free end into a transparent vessel partially filled with liquid.
Pic. 6-7. Removing air from the hydraulic brake drive.
While depressing the brake pedal, loosen the union ½-3/4 turn. Continuing to press the pedal, force the liquid along with the air through the hose into the vessel. After the brake pedal has reached its full forward position and fluid has stopped flowing through the hose, tighten the air outlet fitting until it stops. Repeat these operations until the air bubbles are completely out of the hose. Then, while holding the brake pedal down, tighten the air outlet fitting until it stops and remove the hose. Wipe dry the fitting and put on the protective cap.
Perform all the above operations first on the right rear wheel, then on the left front wheel. This will remove air from one circuit. To pump another circuit, repeat pumping in the sequence: left rear - right front wheel.
When removing air, maintain a normal fluid level in the brake fluid reservoir. If there is no air in the drive, the brake pedal should not travel more than half of its full travel.
Perform air removal with loaded rear wheels (hanging the rear of the car is not allowed).
If the brake fluid has been completely drained from the system, before bleeding:
- unscrew the air bleed fittings on the cylinders of all wheels by 1.5-2 turns;
- sharply pressing the brake pedal and slowly releasing it, tighten the fittings as fluid flows out of them. Then bleed the hydraulic brakes as described above.
If, even after prolonged removal, air continues to escape from the hose into the vessel in the form of bubbles, it means that it enters the system through damage in the pipelines, due to insufficient tightness of the connections or due to a malfunction of the main or wheel cylinders.
When bleeding on a vehicle whose brake system has been in operation for a long time, replace the fluid in the system with a new one.