11:11. Removal of air from the brake system

Cars without ASR traction control system


The control electronic device of Mercedes is necessary for removal of air from the brake system of the car with ASR. The device is connected to the diagnostic plug on the right in a motor compartment. When pressing a key air from ASR system automatically is removed.

After each repair of brakes at which the brake system opened air which surely has to be removed from there can get into pressure head pipelines. A sign of availability of air in pipelines of system is lowering of a pedal of brakes when pressing it a leg without notable resistance. In this case it is necessary to eliminate leakage and to remove air from system.

Air is given by pressing a brake pedal, at the same time still the assistant is necessary. If it is necessary to remove air from all brake system, then it should be deleted from each brake cylinder separately. At regular replacement of brake fluid within maintenance it is necessary to delete air from all four brake cylinders that it did not get into the brake system.

Sequence of removal of air:

1. Right back support.

2. Left back support.

3. Forward right support.

4. Forward left support.

If the support was replaced or under repair, as a rule, enough removal of air from the corresponding cylinder. If repair was made at an empty tank for brake fluid, then removal of air from all brake system is necessary.

Before removal of air unscrew a cover of a tank of brake fluid and fill in brake fluid to the mark "max".


During removal of air watch a tank of brake fluid. Level of brake fluid should not fall too low, otherwise through a tank air will be soaked up. Always add only fresh brake fluid!

1. Take off a dustproof cap from the valve of a sapun of a support. Clean the valve, put on a pure hose, and lower other end of a hose in the vessel half filled with brake fluid.
2. Charge to the assistant to press a brake pedal ("to swing") until in the brake system there is pressure that is felt on increase of resistance when pressing a pedal.
3. When sufficient pressure is created, completely press a brake pedal and you keep it in such situation.
4. Open the valve of a sapun on a support turn of a wrench approximately half way. Collect the pouring-out liquid in a vessel, you watch that the end of a hose constantly was lower than the level of liquid in a vessel.
5. As soon as pressure of liquid decreases, at once close the valve of a sapun.
6. Repeat inflating process, pressure will not increase yet. Press a brake pedal down to refusal, you hold a leg on a pedal, open the screw of the valve of a sapun, pressure will not fall down yet, and twirl the valve screw.
7. Repeat this operation on one brake cylinder until emergence of vials of air in the brake fluid which is flowing down in a vessel stops. About 80 ml of brake fluid from one brake cylinder have to flow out.
8. After the end of pumping remove a hose from the air valve of a sapun, put on a dustproof cap. The valve screw easily tighten with the moment 7 N. of m.
9. Also remove air from other brake cylinders.

During removal of air you watch a leveling tank. Level of brake fluid should not fall too low, otherwise through a tank air will be soaked up. Add only fresh brake fluid.

10. After the end of removal of air add in a tank of brake fluid to the mark "max". Screw up a cover.

Carry out safety control:

      – whether pumping screws are tightened;
      – whether as it should be level of brake fluid;
      – at the working engine make tightness control. For this purpose press a brake pedal with effort from 200 to 300 N (20–30 kg) within about 10 seconds. The pedal should not move. Check tightness of all connections.

11. In conclusion make several braking on the quiet street.