Brake System, Bleeding

Brake System, Bleeding

Procedure covers bleeding of the brake system using the brake charger/bleeder unit (VAS 5234) and (VAG 1869).

• Bleeding the braking system on vehicles with Anti-lock Brake System (ABS) is carried out the same 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.

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

Special tools, testers and auxiliary items required

• Brake charger/bleeder unit (VAS 5234)

• or

• Brake filler/bleeder unit (V.A.G 1869)

• Brake filler/bleeder unit suction adapter (V.A.G 1869/4)

Commercially available tool





• If one chamber of brake fluid reservoir has been run completely empty on vehicles with ABS/ Anti-Slip Regulation (ASR) or ABS/Electronic Differential Lock (EDL)/ASR/Electronic Stabilization Program (ESP) (e.g. leaks in brake system), a pre-bleeding of the brake system must be performed first.

- Remove the rear wheels.

Pre-Bleeding

- Connect the (VAS 5234) or the (VAG 1869).

Bleeding sequence:

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

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

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

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

Initiate basic setting (to bleed brake system):

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

- Then, brake system must be bled normally.

Normal Bleeding

Adhere strictly to work sequence when bleeding brake system.

- Connect the (VAS 5234) or the (VAG 1869).

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

1- Left front caliper

2 - Right front caliper

3 - Left rear caliper

4 - Right rear caliper

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

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

Post-Bleeding

A second mechanic is required to assist:

- Press the brake pedal forcefully and hold.

- Open the bleeder valve at the brake caliper.

- Press the brake pedal down to the floor.

- Close the bleeder screw with the pedal pressed.

- Release the brake pedal slowly.

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

Bleeding sequence:

1- Left front caliper

2 - Right front caliper

3 - Left rear caliper

4 - Right rear caliper

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

- Install the rear wheels.

Brake Fluid, Changing Every 2 Years

Changing brake fluid.