Removal of air from pipelines of system of a hydraulic drive of brakes of the left forward wheel
1 - hose for pumping brakes; 2 - vessel for brake fluid
The air that got into the brake hydraulic drive when replacing the pipeline, hoses, sealing rings or system leaks causes an increase in the brake pedal stroke, its "softness" and significantly reduces the effectiveness of the brakes.
When removing air, maintain a normal fluid level in the brake fluid reservoir.
If there is no air in the brake drive, the brake pedal should not travel more than 1/2–3/4 of its travel.
To eliminate the influence of the vacuum booster and the pressure regulator on the pumping of the brake drive, bleed the air with the engine off and the rear wheels loaded (hanging the rear of the car is not allowed).
1. 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".
2. Thoroughly clean the bleeder fittings of dirt and dust and remove the protective caps from them.
3. Air is removed first from one circuit, then from another, starting each time with the wheel furthest from the master cylinder.
4. Having removed the front wheel, put rubber hose 1 on the fitting head, and lower the other end of the hose into a transparent vessel 2, partially filled with liquid.
5. Having sharply pressed the brake pedal 3-5 times, with intervals between pressing 2-3 s, unscrew the fitting by 1/2-3/4 turn with the pedal pressed.
6. Continuing to press the pedal, force the liquid in the system together with air through the hose into the vessel.
7. 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. These operations must be repeated until bubbles exit the hose.
8. While holding the pedal down, tighten the air outlet fitting until it stops and remove the hose.
9. Wipe dry the fitting and put on the protective cap.
10. 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.
11. If the brake fluid has been completely drained from the system, before bleeding the system:
- unscrew the air removal fittings on the cylinders of all wheels by 1.5–2 turns;
– sharply pressing a brake pedal and slowly releasing it, wrap unions in process of liquid effluence from them. Then bleed the drive, as indicated in paragraphs. 4–10.
12. If, even after prolonged removal, air continues to exit the hose in the form of bubbles, then it enters the system through damage in the pipelines due to insufficient tightness of the connection or due to a malfunction of the master or wheel cylinders.
13. 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. Liquid suitable for further use must be carefully filtered and then settled in a hermetically sealed vessel.