Brake Bleeding: Service and Repair
Brake System, Bleeding
=> [ Bleeding Procedure ]
=> [ Brake system, bleeding without brake filler and bleeder tool ]
• Do not, under any circumstances, allow brake fluid to come into contact with any fluids containing mineral oil (oil, gasoline, cleaning solvents). Mineral oil damages the plugs and rubber grommets in the brake system.
• Brake fluid is poisonous. NEVER siphon brake fluid with your mouth! Also due to its corrosive effect, brake fluid must not come into contact with paintwork.
• Brake fluid is hygroscopic, meaning that it absorbs moisture from the surrounding air, and must therefore be stored in air-tight containers.
• When bleeding, brake fluid that has been flushed through must not be reused and must be disposed of properly.
• Observe disposal regulations. Refer to => [ Brake Fluid ] Description and Operation.
• Only use new brake fluid conforming to US-Norm FMVSS 116 DOT 4.
• Genuine VW/Audi brake fluid conforms to this specification.
• Do not use any silicone-based fluid.
• Avoid contaminating brake fluid with particles or lint (e.g. from cleaning cloths).
• Rinse off any spilled brake fluid using plenty of water.
• Do not work with compressed air and do not move vehicle while the system is open.
• During the final road test, ensure that a ABS-controlled brake test is performed at least once (pulsation must be felt at the brake pedal).
Bleeding Procedure
Special tools, testers and auxiliary items required
• Brake filler/bleeder unit (VAS 5234)
• Brake bleeding wrench (VAS 5519)
• Brake bleed tool (VAS 6564)
• Vehicle Diagnosis, Testing and Information System (VAS 505 x)
• Container
Procedure
- Fill the brake fluid reservoir up to the "MAX" mark.
- Connect the (VAS 5234) with the adapter (VAS 5234/1).
- Attach the adapter - 1 - to the brake fluid reservoir.
- Adjust the pressure on (VAS 5234).
- Follow the (VAS 5234) operating instructions.
• Use suitable bleeder hose. It must fit tightly on bleeder valve so that no air gets into brake system.
- Remove the left and right front caps - 1 -.
- Remove the left and right rear caps - 1 -.
- Attach the bleed hose from the bleeder bottle to the bleed screw.
Bleeding Sequence
1 Left front brake caliper
2 Right front brake caliper
3 Left rear brake caliper
4 Right rear brake caliper
- Leave the bleeder screw open, with brake fluid hose connected, until brake fluid flows out clear and free of air bubbles.
- Press brake pedal 5 times to assist bleeding procedure.
- Tighten bleeder screw to 10 Nm, pull off bleeder hose and place protective cap onto bleeder screw.
- Repeat the bleeding procedure in the specified sequence on the remaining brake calipers.
- Install the left and right front caps - 1 -.
- Install the left and right rear caps - 1 -.
- Fill the brake fluid reservoir up to the "MAX" mark.
• Do not add more brake fluid above the "MAX" mark - 1 - otherwise it will leak out of the reservoir.
- Start the engine and check the brake pedal travel and pressure.
- If the brake pedal travel is too far, check the brake system for leaks and/or repeat the bleeding procedure.
After bleeding brake system, perform zero adjustment on Brake Pressure Sensor 1 (G201) using (VAS 505 x) in Guided Fault Finding.
• A road test must be performed after bleeding. During this, at least one ABS regulation must be performed at all four wheels!
Make sure the brakes are working correctly before driving the vehicle for the first time.
Brake system, bleeding without brake filler and bleeder tool
Special tools, testers and auxiliary items required
• Container
• Brake bleeding wrench (VAS 5519)
• Brake bleed tool (VAS 6564)
• Make sure that the brake fluid reservoir is always filled.
Procedure
- Fill the brake fluid reservoir up to the "MAX" mark.
- Remove the left and right front caps - 1 -.
- Remove the left and right rear caps - 1 -.
• Use suitable bleeder hose. It must fit tightly on bleeder valve so that no air gets into brake system.
- Attach the bleed hose from the bleeder bottle to the bleed screw.
Bleeding sequence
1 Left front brake caliper
2 Right front brake caliper
3 Left rear brake caliper
4 Right rear brake caliper
- Build pressure up in brake system by pumping brake pedal.
• Slowly depress the brake pedal to prevent the formation of bubbles.
- As soon as pressure is built up, hold brake pedal in depressed position.
- Open the bleeder screw, with bleeder bottle hose connected, until the pressure is relieved (pedal drops).
- Hold pedal in completely depressed position and close the bleeder screw.
- Release brake pedal and wait approximately 2 seconds so that brake fluid can flow out of the brake fluid reservoir.
- Repeat the procedure until the brake fluid flows out clear and free of bubbles.
- Tighten bleeder screw to 10 Nm, pull off bleeder hose and place protective cap onto bleeder screw.
- Repeat the bleeding procedure in the specified sequence on the remaining brake calipers.
- Install the left and right front caps - 1 -.
- Install the left and right rear caps - 1 -.
- Fill the brake fluid reservoir up to the "MAX" mark.
• Do not add more brake fluid above the "MAX" mark - 1 - otherwise it will leak out of the reservoir.
- Start the engine and test the brake pedal travel and brake pedal pressure.
- If the brake pedal travel is too far, check the brake system for leaks and/or repeat the bleeding procedure.
Brake Fluid, Changing
=> 808
Make sure the brakes are working correctly before driving the vehicle for the first time.