Bleeding the brakes and changing the brake fluid using the filling and bleeding appliance VW 1238/1 — VW

A -
Switch
B -
Fluid capacity gauge
C -
Pressure gauge
D -
Bleeder bottle
E -
Brake pedal operating device

Preparing the appliance:

Fill with brake fluid as required.

Caution!
Only use new, unused brake fluid as per U.S. Standard FMVSS 116 DOT 4. Original VW/Audi brake fluid complies with this specification.
Brake fluid is poisonous. In addition to this, brake fluid should not be allowed to come into contact with paintwork due to its corrosive effect.
Brake fluid is hygroscopic, i.e. it absorbs moisture from the surrounding air and should therfore always be stored in air-tight containers.
Connect appliance to mains. Warning lamp should light up.
Set the operating switch to I. Gauge should indicate a pressure of 2 - 2.5 bar.
Set operating switch to 0.

Bleeding the brake system and checking for leaks

Set up the brake pedal operating device between driver's seat and brake pedal and pretension it.

Take cap off reservoir and remove strainer. Attach the appropriate connector to the thread on the brake fluid container.
Pull out the connecting hose from appliance, and attach to connector.
Align red finger of fluid capacity gauge with black finger so that amount of fluid used can be checked.
Set operating lever to I. The pump then applies pressure to the brake fluid in the vehicle.

Open the bleeder screws in brake calipers, brake pressure regulators and wheel brake cylinders in the prescribed sequence. The used fluid which is bled from the system should be collected in the bleeder bottle.

Bleeding sequence is as follows:

1 -
Rear right wheel cylinder
2 -
Rear left wheel cylinder
3 -
Front right caliper (Upper screw)
4 -
Front left caliper (Upper screw)

Check the brake system for leaks. Set operating switch to 2 and watch gauge. The pressure gauge must not show a drop in pressure.
Remove brake pedal operating device.
Set operating switch to 0.

Then when no pressure is indicated on gauge, detach hose

Check fluid level in brake fluid container and if necessary siphon off surplus using a suction bottle.

Charging brake fluid

Prepare appliance as for bleeding

Using the special suction bottle draw off as much brake fluid as possible from the brake fluid container. (This ensures that the used fluid in the container is not pumped through the brake system).
Set up the brake pedal operating device between driver's seat and brake pedal and pretension.

Attach suitable connector to the thread of brake fluid container.
Pull the connecting hose from appliance and attach to connector.
Set operating switch to I. Open the bleeder screws in the sequence shown in the following table, and allow the appropriate quantities of fluid to flow out. This ensures that the used brake fluid is pushed out of the system as new fluid is pumped in.

Sequence Wheel cylinder · Amount of fluid which must flow from cylinders and calipers
rear right · 500 cm3
rear left · 500 cm3
front right lower · 500 cm3
front right upper · 100 cm3
front left lower · 500 cm3
front left upper · 100 cm3

Check the brake system for leaks. Set operating switch to 2 and watch gauge. The gauge must not show a drop in pressure.
Remove brake pedal depresser.

Set operating switch to 0.

Then when the pressure gauge shows no pressure, detach hose.

Check fluid level in the brake fluid container and if necessary draw off surplus using a suction bottle.

Bleeding the brake system and changing the fluid without using brake filling and bleeding appliance

This method should only be employed when a suitable appliance is not available.

Bleeding

Build up pressure in the brake system by pumping the pedal. With the bleeder bottle tube attached open the bleeder screw. With the brake pedal held down close bleeder screw. Repeat procedure until no more air is present in system. For bleeding sequence see => page
47-33

Changing brake fluid

Using the special suction bottle draw off as much brake fluid as possible from brake fluid container. By opening the bleeder screws and pumping the brake pedal, pump the fluid from all brake cylinders. Fill system with new fluid and bleed as described above