Caution: Contact with brake fluid is hazardous to health. Do not suck it out with your mouth through a hose. Store brake fluid only in a container that is out of the reach of children.
1. Brake fluid has the ability to absorb moisture, as a result of which its boiling point decreases over time. Under significant load on the brakes, this can lead to the formation of vapor bubbles in the brake lines and reduce the effectiveness of the brakes.
2. To change the brake fluid you will need the help of an assistant, but this procedure can be carried out without assistance using a special device (for example, the branded VAS5234), - see the instructions supplied with such a device. When using the device, the brake system pressure should not exceed 2 bar. When bleeding the brake system, the vehicle should be level to ensure proper monitoring of the brake fluid level in the reservoir.
3. Turn off the ignition and disconnect the negative battery cable (see Chapter 5).
4. Remove the cap from the brake fluid reservoir (5 in the illustration at the beginning of the chapter). To access the brake fluid reservoir, remove the right air intake chamber cover (see section 19).
5. Mark the current brake fluid level on the wall of the reservoir with a felt-tip pen to prevent it from being exceeded when replacing the brake pads. With the filter installed, pump out as much brake fluid as possible from the reservoir, leaving a layer of fluid approximately 10 mm deep at the bottom. Tighten the service plug.
Note: Do not remove all the fluid from the reservoir, otherwise air will enter the hydraulic drive of the brake system.
6. Fill the reservoir with fresh brake fluid up to the "MAX" mark.
7. Jack up the car. Thoroughly clean and remove the protective caps from the bleed nipples (see illustrations).
9.7a. Front brake mechanism bleeder nipple boot.
9.7b. Rear brake bleeder nipple boot.
Attach one end of a clean, clear hose to the front left brake bleeder nipple (see Chapter 8), and insert the other end into a container to collect the brake fluid. Pour a small amount of brake fluid into the container and ensure the end of the hose remains submerged. Raise the container at least 30 cm above the bleeder nipple to maintain pressure and prevent air from entering.
8. Ask an assistant to sharply press the brake pedal 3-5 times at intervals of 2-3 seconds and release the nipple half a turn with the pedal depressed. Once the brake pedal hits the floor, tighten the bleed nipple. Take your foot off the pedal. Repeat this process to pump out the old brake fluid (until a new one appears, which can be recognized by its light color) Approximately 0.2 liters of brake fluid should be pumped out of each front bleed nipple.
Note: If the liquid layer at the bottom of the tank is less than 10 mm, the system will have to be pumped.
9. Tighten the bleed screw, close its protective cap and add new brake fluid to the reservoir.
10. In the same way, pump out the old brake fluid sequentially from the front left, rear right and rear left brake mechanisms. Approximately 0.3 liters of brake fluid should be pumped out of each rear bleed nipple.
Caution: The drained brake fluid must in any case be clean and free of air bubbles.
11. Adjust the brake fluid level according to the previously applied mark. Press the brake pedal and check its free play. Make sure that the brake pedal does not "sink" when you press it - the free travel of the pedal should be no more than 1/3 of its full travel.
12. Connect the negative cable to the battery and test the brakes on a lightly trafficked road. To do this, you should perform at least one strong braking, while checking the operation of the ABS (with appropriate configuration). A sign that the ABS is working properly is a pulsation in the brake pedal when braking.
Note: The ABS effect is best seen on unpaved roads.