10.5.3. Pumping of the brake system

For reliable operation of the brake system it is necessary to remove from it all air. Before pumping of system check liquid level in a tank and, if necessary, add. Make sure that terms of replacement of brake fluid did not pass.


  1. Check all connecting details of brake lines for tightness. Look whether hoses are worn-out and whether there are on them no cracks and cuts.
  2. If you doubt a brake bracket or the wheel cylinder, it is necessary to examine them on liquid leak traces.
  3. Prepare a pure vessel, a piece of a rubber tube which densely would get on the drain valve, and brake fluid.
  4. The first pump over the main cylinder (see Removal of air from the main cylinder).
  5. Weaken a nut in the place of connection of the hydraulic line to the main cylinder.
  6. Ask the assistant to drown slowly a brake pedal in a floor that will force the air which is in the main cylinder to leave through the weakened connection.
  7. At completely pressed pedal delay connection. Release a pedal. The pedal cannot be released until you do not delay connection since otherwise air can get to the cylinder.
  8. Repeat this procedure until of the cylinder does not cease to go out air.
  9. Pump over hydraulic systems separately, since the longest line (back).
  10. For pumping of the brake system clear surfaces near drain valves. Remove a rubber cap from the drain valve and put on a piece of a rubber tube the nipple.
  11. Lower other end of a tube in a vessel in which so much brake fluid that during pumping the end of a tube remained shipped in it has to be poured.
  12. Open the drain valve approximately on 3/4 turns and ask the assistant to drown slowly a brake pedal in a floor and to keep it in this situation.
  13. Close the drain valve and release a pedal.
  14. Carry out this operation until vials of air cease to leave.
  15. Pumping over system, periodically check liquid level in a tank. It has to be filled up to the top, otherwise air will get to system again. Do not add the liquid which is already extorted from system in a tank.
  16. Repeat all procedure for the second back wheel.
  17. Pumping of the forward brake system is carried out similarly.
  18. Fill the main cylinder with liquid so that its level in a tank was about 6 — 7 mm lower than the upper edge.
  19. Check operation of the indicator of level of brake fluid, having pressed a black rubber pear in the top part of a tank (at the included ignition). The bulb on the control panel has to light up.
  20. Check feeling for brake pedals: it has to be rigid and not give feeling of failures ("viscosity") which is a sign of availability of air in a hydraulic actuator.