34 00 519 Checking service brake: high- and lowpressure tests
IMPORTANT:
The high/low-pressure test (leakage test) must be carried out with the engine switched off. 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 34 00 TESTING AND BLEEDING BRAKES E38 .
After 2 minutes, pressure is permitted to drop by max. 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.