To fill the system, use glycol brake fluids with parameters according to FMVSS 116 not lower than DOT-3.
Before replacing the brake fluid, check the hydraulic drive for leaks (see "Checking the tightness of the brake hydraulic drive") and troubleshoot.
You will need: an 8 mm spanner, brake fluid, a flexible tube, a container for collecting brake fluid, and a clean rag.
Warning! 1. Take precautions when working with brake fluid: it is toxic. If brake fluid gets on wires, plastic or painted body parts, it may cause damage. Therefore, always place clean rags underneath when pouring. If liquid gets on parts, wipe them off immediately with a clean cloth.
Caution! 2. Use only brake fluid recommended by the manufacturer.
Attention! 3. Do not reuse the fluid drained from the system: it is contaminated, saturated with air and moisture. Always add only new fluid of the same brand that was previously added to the system.
Attention! 4. Brake fluid is hygroscopic (absorbs moisture from the surrounding air), therefore it cannot be stored in an open container.
1. Unscrew the cap of the master cylinder reservoir and wipe the float with a clean cloth. Be careful: brake fluid may drip from the float.
2. If the rear wheels are raised, first unlock the rear brake pressure regulator by inserting a screwdriver between the plate and the piston. Don't forget to take it out when you're done.
3. Clean the right rear brake release valve from dirt. Remove the rubber protective cap from the valve.
4. Put on the rubber hose (it is recommended to use a transparent hose to see the state of the flowing liquid) onto the valve nipple and immerse the end of the hose in a clean transparent container.
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.
Material was taken from the website LadaMan
6. Loosen the air release valve 1/2–3/4 of a turn. Old (dirty) brake fluid will start to flow out of the hose. In this case, the brake pedal should smoothly reach the stop. Once the liquid stops flowing, close the air release valve.
7. Constantly monitor the fluid level in the reservoir, not allowing it to fall below the "MIN" mark, and add new brake fluid if necessary. Repeat steps 5 and 6 until new (clean) brake fluid begins to flow out of the hose.
8. In the same way, replace the brake fluid in the left front brake mechanism, and then in the second circuit (first in the left rear brake mechanism, then in the right front).
9. Press the brake pedal several times. The pedal travel and resistance should be constant with each press. If these conditions are not met, then air has entered the brake system and it needs to be bled (see "Bleeding the hydraulic brake system").
10. After replacing the brake fluid, be sure to put the protective caps on the air release valves.
11. Add brake fluid to the reservoir up to the "MAX" mark and tighten the cap.