Brake Bleeding: Service and Repair

Brake System, Bleeding

Special tools, testers and auxiliary items required

• Brake filler/bleeder unit (VAS 5234)

• Bleeding the braking system on vehicles with ABS is carried out as for vehicles with conventional braking systems.

• 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 spills, by using plenty of water.

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

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

• If one chamber of the brake fluid reservoir has run completely empty (e.g. leak in the brake system), the brake system must be pre-bled first.

Pre-Bleeding

• There are two bleeder valves installed on Brembo brake calipers Always bleed at both bleeder valves.

• Bleed at outer bleeder valve first.

- Connect (VAS 5234).

Bleeding sequence:

1 - Bleed left front and right front brake caliper together simultaneously

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

Depending on the version, each front brake caliper has two bleeder screws. To achieve optimum brake system bleeding, bleed the respective brake caliper at both bleeder screws. Always bleed the outer screw first, then the inner one.

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

- Then, brake system must be bled normally

Normal Bleeding

• Adhere strictly to work sequence when bleeding brake system.

• There are two bleeder valves installed on Brembo brake calipers. Always bleed at both bleeder valves.

• Bleed at outer bleeder valve first.

- Connect (VAS 5234).

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

Depending on the version, each front brake caliper has two bleeder screws. To achieve optimum brake system bleeding, bleed the respective brake caliper at both bleeder screws. Always bleed the outer screw first, then the inner one.

1 - Right rear brake caliper

2 - Left rear brake caliper

3 - Right front brake caliper

4 - Front left brake caliper

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

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

Post-Bleeding

A second mechanic is required to assist:

- Depress brake pedal forcefully and hold.

- Open bleeder valve at brake caliper.

- Press brake pedal down onto stop.

- Close bleeder valve with pedal depressed.

- Release brake pedal slowly.

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

Depending on the version, each front brake caliper has two bleeder screws. To achieve optimum brake system bleeding, bleed the respective brake caliper at both bleeder screws. Always bleed the outer screw first, then the inner one.

Bleeding sequence:

1 - Right rear brake caliper

2 - Left rear brake caliper

3 - Right front brake caliper

4- Front left brake caliper

• A road test must be performed after bleeding. At least one ABS regulation should be performed during this!