New brake fluid will be required for bleeding. Company "Volkswagen" recommends using brake fluid of the brand "FMVSS 116 DOT 4".
Before bleeding the brake system, make sure that all brake drive units and their connections are tight, clean the cover and the surface around the reservoir cover, and thoroughly clean the bleeding nipples. Bleeding the brake system is necessary after each repair of the brake system if the hydraulic brake drive system was opened.
It is recommended to start bleeding from the caliper that was replaced or repaired. Observe the following sequence of brake mechanisms to be bled:
- rear right brake caliper;
- rear left brake caliper;
- front right brake caliper;
- front left brake caliper.
Attention! During bleeding, constantly monitor the brake fluid level in the reservoir and maintain it at the "Max" mark.
Note: It is not recommended to use the fluid drained from the system to fill the reservoir, as it is saturated with air, contains a lot of moisture and may be contaminated.
Bleed the brake mechanisms in the following order:
- remove the dust cap, clean the bleed nipple and put a rubber hose on it to drain the fluid, and lower its free end into a transparent container partially filled with brake fluid;
- ask an assistant to press the brake pedal sharply several times until it feels a sharp resistance;
- unscrew the nipple by 1/2-1/4 turn with the pedal pressed. Continuing to press the brake pedal, force out the liquid in the system together with the air through the hose into the container. The brake pedal will "go" to the floor, hold it in this position, screw in the bleed nipple;
Note: Make sure the end of the hose is always immersed in the liquid.
- repeat these operations until air bubbles stop coming out of the hose;
- add brake fluid to the reservoir, keeping the level around the "Max" mark;
- keeping the brake pedal depressed, tighten the nipple until it stops and put on the protective cap;
- repeat the operations for other wheels;
- check the rubber seal of the tank lid;
- after bleeding, add brake fluid to the reservoir up to the "Max" mark;
- check the tightness of all system connections;
- take a test drive, and exercise caution during this.
Replacing brake fluid
Replace the brake fluid every two years. At the service station, the brake fluid is replaced using a special device for filling and bleeding the brake system. The device cylinder is filled with compressed air under a pressure of approximately 400 kPa. To replace the fluid and bleed, the device's operating pressure is set to 100 kPa.
However, you can replace the brake fluid yourself. This will require approximately 2 liters of fresh brake fluid of the specified brand.
To prevent air from getting into the hydraulic drive system when replacing the brake fluid and to spend a minimum amount of time on this operation, adhere to the following rules:
- follow the same procedure as when bleeding the brakes, but use a hose with a glass tube at the end, which you lower into a container with brake fluid;
- press the brake pedal and pump out the old brake fluid until new fluid appears in the tube, then perform two full strokes of the brake pedal and, holding it in the pressed position, tighten the nipple;
- constantly monitor the brake fluid level in the reservoir and top up the fluid to the "Max" level in a timely manner;
- repeat this operation on each brake cylinder in the same order as when bleeding;
- after replacing the brake fluid, fill the reservoir to the maximum level and check the operation of the brakes while driving the car, being careful.
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