Brake Bleeding: Service and Repair

The bleeding the brake system is described for brake charge and bleed units VAS 5234 and VAG 1869.
^ 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 standard FMVSS 116 DOT 4.
^ Genuine VWI Audi brake fluid conforms to this specification.
^ Brake fluid is poisonous. Due to its corrosive nature brake fluid must not come into contact with paint.
^ Brake fluid is hydroscopic, which means it absorbs moisture from the ambient air and must therefore always be stored in airtight containers.
^ Rinse off spillages, by using plenty of water.

Bleeding with brake charge and bleed unit VAS 5234 or VAG 1869

Special tools and workshop equipment required





^ VAS 5234 Brake charge and bleed unit

or





^ VAG 1869 Brake filling and bleeder unit
Follow work sequence when bleeding brake system exactly.

Pre-bleeding
^ Connect brake charge and bleed unit VAS 5234 or VAG 1869.
^ Open bleed screws in the specified order and bleed brake calipers.
Bleeding sequence

Use suitable bleeder hose. It must fit tightly on bleeder screw so that no air can enter brake system.
^ With bleeder hoses still installed leave brake caliper bleed screws open until brake fluid discharges free of air bubbles.

Subsequent bleeding
Then bleed, with filler and bleeder unit connected. To do this a second mechanic is required:
^ Depress brake pedal forcefully and hold.
^ Open bleed screw on right-rear brake caliper.
^ Press brake pedal down until stop.
^ Close bleed screw with pedal held down.
^ Release brake pedal slowly.

This bleed sequence must be carried out 5 times per brake caliper.

Bleeding sequence
1 - Right-rear brake caliper
2 - Left rear brake caliper
3 - Right front brake caliper
4 - Left front brake caliper

Vehicles with ABS, ABS/EDL, ABS/EDL with ASR or ABS/EDL with ASR.
With these vehicles a test drive must be carried out after bleeding brakes. When doing this, an ABS regulation must be performed at least once!

Brake system, bleeding without brake filling and bleeding appliance
^ Build-up brake pressure in brake system by pumping the brake pedal.
^ Attach bleeder bottle hose and open bleed screw.
^ With brake pedal held down, close bleed screw.
^ Repeat operation until no air is present.
Bleeding sequence