Brake Bleeding: Service and Repair

Brake System Bleeding

Special tools, testers and auxiliary items required

• Brake Charger/Bleeder Unit (VAS 5234)

• Brake Charger/Bleeder Unit (V.A.G 1869)

• Suction Adapters (V.A.G 1869/4)

Procedure covers bleeding of the brake system using the brake charger/bleeder unit (VAS 5234) or (V.A.G 1869).

• Bleeding the brake system on vehicles with Anti-lock Brake System (ABS) is carried out the same as for vehicles with a conventional brake system.

• Only use new brake fluid conforming to US-Norm FMVSS 116 DOT 4.

• Genuine VW/Audi brake fluid conforms to this specification.

• Brake fluid is poisonous. Due to its caustic nature, it must also never be brought into contact with paint.

• Brake fluid is hygroscopic, meaning that it absorbs moisture from the surrounding air, and must therefore be stored in air tight containers.

• Rinse off any spilled brake fluid using plenty of water.

There must be a positive pressure of 2 bar to bleed the hydraulic unit.

• If one chamber in the brake fluid reservoir runs empty, for example if there is a leak in the brake system, then it is necessary to bleed the brake system.

Pre-Bleeding

• There are 2 bleeder valves installed on the Brembo brake calipers, always bleed at both the valves.

• Bleed at the outer valve first.

- Connect the (VAS 5234) or (V.A.G 1869).

Bleeding sequence:

1 - Bleed the left front and right front brake calipers simultaneously.

2 - Bleed the left rear and right rear brake caliper together simultaneously.

- With the bleeder bottle hoses attached, leave the valves open long enough that the brake fluid exits without bubbles.

Then the hydraulic unit must be bled once more via the function "Basic setting" using the (VAS 5051).

Initiate basic setting (to bleed the brake system):

(VAS 5051), connecting and selecting functions. Refer to => [ VAS 5051, Connecting and Selecting Functions ] Testing and Inspection.

- Then, the brake system must be bled normally

After bleeding the brake system, basic setting for the brake pressure sensor 1 (G201) must be performed.

Bleeding

Adhere strictly to the sequence when bleeding the brake system.

• There are 2 bleeder valves installed on the Brembo brake calipers, always bleed at both the valves.

• Bleed at the outer valve first.

- Connect the (VAS 5234) or (V.A.G 1869).

- Open the bleeder valves in the prescribed sequence and bleed the brake calipers.

1 - Right rear

2 - Left rear

3 - Right front

4- Left front

Use a suitable bleeder hose. It must fit tightly on the valve so that no air gets into the brake system.

- With the bleeder bottle hose attached, leave the valves open long enough that the brake fluid exits without bubbles.

Post-Bleeding

A second mechanic is required to assist:

- Press the brake pedal forcefully and hold.

- Open the valve at the brake caliper.

- Press the brake pedal down to the floor.

- Close the valve with the pedal pressed.

- Release the brake pedal slowly.

This bleeding procedure must be performed 5 times per brake caliper.

Bleeding sequence:

1 - Right rear

2 - Left rear

3 - Right front

4- Left front

A road test must be performed after bleeding. During this, at least one ABS regulation stop must be performed!