Air is bled from the brakes by depressing the brake pedal, so an assistant is needed for this operation.
In workshops, the air is removed, as a rule, with the help of a special device. This device pumps brake fluid through the brake circuits at a pressure of not more than 2.0 bar.
If you need to remove air from the entire brake system, then the air is removed from the brakes of each wheel individually. This procedure is performed when air has entered through the reservoir or into each brake cylinder. If only one caliper was replaced or repaired, then it is quite enough to remove air only from it.
Air removal sequence:
- 1 — a support of a back right wheel;
- 2 — a support of a back left wheel;
- 3 — a support of a forward right wheel;
- 4 - support of the front left wheels.
Remove the cap from the bleed valve on the caliper. Clean the valve, put a clean transparent hose on it, lower the other end into a container half filled with brake fluid.
Have an assistant move the brake pedal to pressurize the brake system. This will be felt by the increased resistance when you press the pedal.
When pressure is built up, fully depress the brake pedal and hold it in that position.
Loosen the bleed valve on the caliper with a spanner wrench about half a turn. The brake fluid flowing from the hose must be collected in a container, and the end of the hose must be constantly immersed in the brake fluid. As soon as the liquid stops coming out, tighten the valve.
Repeat the inflation process until pressure builds up and keep the brake pedal depressed. Unscrew the valve to remove air, and when the brake fluid stops coming out of the hose, tighten the valve.
Continue the bleeding process on each caliper until no more air bubbles appear in the brake fluid flowing out of the hose.
After the air has been bled, remove the hose from the bleed valve and put on the protective cap.
Attention: When removing air, it is necessary to periodically check the liquid level in the tank. It should not fall too much, otherwise air will enter the system through the tank. Always top up with fresh brake fluid.
Bleed the remaining calipers in the same way.
After bleeding is complete, add brake fluid to the reservoir to the MAX level.
Check the condition of the rubber gasket (1) in the tank lid.
Do a security check.
After bleeding, when you press the brake pedal, it should be stiff and should not spring. If not, repeat the bleed operation.