10.9. Removal of air from the hydraulic drive of brakes

Air in the hydraulic drive of brakes considerably reduces efficiency of braking. It can get to the hydraulic drive owing to depressurization of system at repair, replacement of separate knots or brake fluid. Point the increased course of a pedal of a brake and its "softness" to availability of air in the drive. Before removal of air check tightness of all knots of the drive of brakes and their connections.
Pumping of hydraulic system of all four brake mechanisms can be required if air got to system owing to the low level of brake fluid or brake tubes were disconnected from the main brake cylinder.
If the brake tube was disconnected only on one wheel, then removal of air only from this working brake cylinder is required (or a support).
If the brake tube was disconnected on the site between the main brake cylinder and any of wheel brake mechanisms, it is necessary to remove air from that part of the brake system to which brake fluid on the disconnected tube arrived.
If removed the main brake cylinder from the car, remove air before its installation.
If the main brake cylinder is installed on the car, but it is known that in it there is an air, it needs to be pumped over before pumping of the working brake cylinder (or a support). Carry out removal of air from the main brake cylinder installed on the car as follows.
Several times press a brake pedal at the stopped engine for removal of vacuum in the vacuum amplifier of brakes.
Uncover a tank and fill it with brake fluid, then in the course of removal of air control liquid level in a tank, adding liquid as required. Establish into place a cover.
Disconnect the forward highway of the brake system from the main brake cylinder.
Let's brake fluid fill the main brake cylinder until it begins to arrive from connection for the forward highway.
Connect the forward highway of the brake system to the main brake cylinder.
Ask the assistant to press very slowly a pedal of a brake and to hold it in this situation.
Weaken a nut of fastening of the forward highway of the brake system on the main brake cylinder, then delay connection and slowly release a brake pedal.
Wait 15 with (it very important).
Repeat operations, including a pause 15 with until all air goes out of the main brake cylinder.
After forward connection is completely cleared of air, remove with a similar way air from back connection.
Before removal of air execute the following operations from separate working brake cylinders or supports.
Several times press a brake pedal at the stopped engine for removal of depression in the vacuum amplifier of brakes.
Uncover a tank of the main brake cylinder and fill it with brake fluid, then in the course of removal of air check liquid level in a tank, adding it as required. Establish into place a cover.
Further perform work with the assistant. You will need the container with fresh brake fluid, an empty transparent plastic container, a set of tubes 500 mm long of plastic, rubber or vinyl for connection to the union of removal of air and a wrench for an otvorachivaniye and a wraparound of the union of removal of air. It is better to lift and fix the car on supports.
Since the right back wheel weaken the union of removal of air a little, then tighten until dense, but quickly and easily weakened inhaling.
Put on one end of a tube the union of removal of air, lower other end in the container with brake fluid.
The assistant has to press several times a brake pedal for creation of pressure in system, then hold a pedal in the pressed situation.
At the pressed pedal release the union of removal of air that brake fluid began to go out of the union. Watch the vials of air leaving through the end of a tube shipped in a container. When the stream of liquid weakens, close the union of removal of air and ask the assistant to release a brake pedal.
Repeat these actions until the tube does not come out brake fluid without vials of air, then tighten the union of pumping and pass to the left back wheel, the right forward wheel and the left forward wheel. Surely check liquid level in a tank. Never use old brake fluid as it contains excessive moisture which will worsen a condition of elements of the brake system.
After removal of air fill up a tank with brake fluid.
If there are any difficulties during removal of air from hydraulic system or not the assistant, it is possible to get a set for pumping under pressure. After its connection according to the instruction each of unions of removal of air can be open serially for removal of liquid under pressure before its release from vials of air, at the same time during pumping it is not required to fill a tank.