Checking Service Brake (High and Low Pressure Leak Tests)

High Pressure Leak Test

CAUTION: Engine must be stopped for the high pressure leak test.

- Discharge the hydraulic reservoir by operating the brake pedal 20 times with the engine stopped and a force equal to full stop braking.
- Test both brake circuits.
1st circuit = front right and rear left
2nd circult = front left and rear right
- Unscrew bleeder screw of the 2nd brake circuit.
- Connect and bleed a pressure tester.





- Apply a force of 675 N (149 lbs) on the brake pedal.
In so doing the hydraulic line pressure of the service brakes must show specified pressure of 50 bar (710 lbs). Pressure may drop by max. 8% after 2 minutes.
- Perform same test on the 1st brake circuit





Low Pressure Leak Test
- Test both brake circuits.
- Take back the pedal prop until testing pressure in the brake system is 2 to 5 bar (28 to 71 psi). Car and tester must remain still, since any motion would produce wrong readings.

Pressure must remain constant during the 5 minute test.

- Check rubber parts, if the pressure drop is considerable.
- Bleed calipers after finishing the test.