Checking Service Brake: High and Low Pressure Tests

34 00 519 Checking service brake: high- and low pressure tests

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

Observe safety instructions on raising the vehicle.





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.





Load brake pedal with a force and block brake pedal with pedal support, refer to Technical Data.
After 2 minutes, pressure is permitted to drop by maximum 8%.





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.