An indication of the presence of air in the brake system is an increased travel and "softness" of the brake pedal.
Before bleeding the brake system, inspect it to ensure it is tight.
1. Clean the air release valve on the brake mechanism from dirt and dust.
2. Check the level and, if necessary, add brake fluid to the reservoir up to the "MAX" mark.
3. Remove the protective cap from the air release valve.
4. Place a rubber hose over the valve head and submerge the end of the hose in a clean, clear container partially filled with brake fluid.
5. The assistant should press the brake pedal sharply 4-5 times (with an interval of 1-2 seconds between presses). After the last pumping, the pedal should be kept pressed.
6. Loosen the air release valve by ½-¾ turn. Air bubbles will be visible in the fluid flowing out of the hose. When the fluid stops flowing out of the hose, close the release valve completely, after which the assistant should release the brake pedal.
7. Repeat steps 5–6 until the fluid stops bubbling. When bleeding, check the brake fluid level and add more to the reservoir if necessary, not allowing the level to drop below the "MIN" mark.
8. Remove the hose, wipe the valve nipple dry and put the cap on it.
9. Bleed the brakes on the remaining wheels if necessary.