Before removing air from the brake system, make sure that all brake drive units and their connections are tight, check and, if necessary, fill the tank to a normal level with liquid «Neva» or «Tom». Then carefully clean the bleeder fittings from dirt and dust and remove the protective caps from them. Remove air first from one circuit, then from the other, starting each time with the wheel furthest from the master cylinder.
The pumping of the hydraulic drive is carried out in the following order:
- remove the front wheels, put on the fitting head 1 (pic. 200) rubber hose, and lower the other end of the hose into a transparent vessel partially filled with brake fluid;
- sharply pressing the brake pedal 3-5 times with intervals between pressing 2-3 s, unscrew fitting 1 by 1/2-3/4 turn with the pedal depressed. Continuing to press the pedal, force the liquid in the system together with air through the hose into the vessel;
- when the brake pedal reaches the extreme forward position and the outflow of fluid through the hose stops, tighten the fitting until it stops. Repeat these operations until the exit of bubbles from the hose stops;
- while holding the pedal down, tighten the fitting to failure and remove the hose, wipe the fitting dry and put on the protective cap;
- repeat the operations for other wheels, first on the second wheel of the same circuit, and then sequentially on both wheels of the second circuit.
When removing air, maintain a normal fluid level in the brake fluid reservoir. After complete removal of air, the brake pedal should not pass more than 1/2-3/4 of its travel.
To eliminate the influence of the vacuum booster and pressure regulator on the bleeding of the hydraulic drive of the brakes, carry out the removal of air with the engine off and the rear wheels loaded (hanging the rear of the car is not allowed).
If the liquid was drained completely, then before removing air from the system: unscrew the fittings on the cylinders of all wheels by 1.5-2 turns; sharply pressing the brake pedal and slowly lowering it, wrap the fittings as fluid flows out of them. Then bleed the drive as above.
If, even after prolonged removal, air continues to exit the hose 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 master or wheel cylinders.
If bleeding is performed on a vehicle whose brake system has worked for a long time, then replace the fluid in the system with a new one.