34 00 519 Checking Service Brake: High- And Low-Pressure Tests

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IMPORTANT: The high/low-pressure test (leakage test) must be carried out with the engine switched off.

Observe safety instructions on raising the vehicle. Refer to 00..... LIFTING VEHICLE WITH A LIFTING PLATFORM .

High-pressure test (leakage test):

Perform test on both brake circuits.

1st brake circuit, front axle.

2nd brake circuit, rear axle.

Remove bleeder screw, connect pressure tester and bleed.

Fig 1: Connecting Pressure Tester

Courtesy of BMW OF NORTH AMERICA, INC.

Load brake pedal with a force and block brake pedal with pedal support.

After 2 minutes, pressure is permitted to drop by max. 8 %.

Fig 2: Blocking Brake Pedal With Pedal Support

Courtesy of BMW OF NORTH AMERICA, INC.

Low-pressure test:

Perform test on both brake circuits.

Reset pedal support until test pressure in braking system is 2-5 bar.

Vehicle and measuring apparatus must remain steady as vibrations will distort the result.

Pressure must remain constant for a test period of 5 minutes.

Check all rubber parts in case of excessive pressure drop.

Bleed brake calipers and wheel brake cylinders after finishing test.

Fig 3: Identifying Pressure Tester

Courtesy of BMW OF NORTH AMERICA, INC.