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Audi Workshop Service and Repair Manuals

High-pressure and low-pressure tests > < Leak test
Leak test performed by operating brake
Leak test performed by operating brake
–  Switch off engine.
–  Press brake pedal repeatedly („pump the brake servo dry“) until there is no more servo assistance and the brake pedal is heavy.
–  Press the brake pedal down approx. 20 mm out of the rest position.
–  Keep the force on the pedal constant for about 20 seconds.
The brake pedal travel should not become longer.
–  Release brake pedal.
–  Press pedal with substantial foot pressure.
–  Keep the force on the pedal constant for about 20 seconds.
The brake pedal travel should not become longer.
The visual inspection of the brake system must be repeated if the brake pedal resistance collapses during any of the tests.
If no leaks are then found during the test, the brake master cylinder probably has a leak and must be renewed.
  Caution
Ensure that no brake fluid enters the brake servo when renewing the brake master cylinder.
   

High-pressure and low-pressure tests > < Leak test