Checking For Leaks

Checking for Leaks

=> [ Brakes, Testing for Leaks ]

=> [ High and Low Pressure Testing ]

• Applies to steel and ceramic brakes.

• The hydraulic brake system must be bled.

• Only install genuine parts or components approved by Audi in the brake system.

• The if the brake fluid replacement interval specified by Audi is exceeded, replace the brake fluid.

• Check the system visually for leaks.

• Fix leaks and remove dirt on the hydraulic system.

Brakes, Testing for Leaks

- Switch the engine off.

- Press the brake pedal until there is no more brake assistance - " pump the brake booster empty". The brake pedal becomes hard.

- Press the brake pedal about 20 mm out of the resting position.

- Hold the force on the pedal steady for about 20 seconds.

The brake pedal travel must not increase.

- Release the brake pedal

- Press firmly on the brake.

- Hold the force on the pedal steady for about 20 seconds.

The brake pedal travel must not increase.

If the pedal sinks down during one of the tests, repeat the visual inspection on the brake system.

If no leaks are found, the brake master cylinder is probably has leaks and must be replaced.

CAUTION!
Brake fluid must not run into the brake booster when replacing the brake master cylinder.

High and Low Pressure Testing

Special tools, testers and auxiliary items required

• Brake pressure gauge 0-250 bar (V.A.G 1310/A)

• OR

• Pressure gauge (V.A.G 1310)

• Brake Pedal Actuator (VAG1869/2)

Before Beginning

Check the brake system (brake master cylinder, brake hoses, brake lines and brake calipers) function and leaks.

High Pressure Testing

- Remove bleeder screw at one of the front brake calipers. Connect (V.A.G 1310) or (V.A.G 1310A) and bleed.





- Install (VAG1869/2) between brake pedal and driver seat. Apply pressure to brake pedal until the gauge indicates a pressure of 50 bar. The pressure must not drop by more than 4 bar during the test period of 45 seconds. If pressure drop is large, replace hydraulic unit.

Low Pressure Testing

- Set the (VAG1869/2) back far enough that the pressure gauge indicates 6 bar positive pressure.

- The pressure must not drop by more than 1 bar during a test period of 3 minutes.

If the pressure drop is large, replace the ABS Hydraulic Unit (N55).