Brake Master Cylinder: Service and Repair

CAUTION:
Bleeding the ABS is not a routine maintenance operation and should only be necessary when part of the system has been disconnected or the fluid is contaminated.

During the bleed procedure, it is important that the level of fluid in the reservoir is maintained at approximately 2 mm below the bottom of the filler neck.

Do not allow the pump motor to run continuously for more than two minutes. If, for any reason the motor does overrun the two minute time limit, switch the ignition OFF and allow the motor to cool for at least ten minutes before continuing with the bleed procedure.

1. Discharge the hydraulic accumulator by operating the brake pedal until the pedal goes hard (approximately 20 times).
2. Place suitable absorbent material around the reservoir area to catch any spilled fluid.





3. Remove the low pressure hose to pump securing clip, disconnect the hose, route the end of the hose into a container, and drain the fluid.





4. Disconnect the reservoir multi plug, remove the reservoir retaining clip bolt (1). Remove the reservoir taking care not to spill any fluid that may not be fully drained.
5. Remove the retaining clip and low pressure hose from the reservoir. Place the reservoir safely to one side.
6. Remove and discard the '0' ring/sleeve seals from the actuation unit. Clean the actuation unit.
7. Reassembly of the new reservoir is a reversal of the removal procedure.

Bleed Procedure--Front
1. Ensure that the vehicle is standing level. Switch the ignition off.





2. Top up the reservoir to approximately 2mm below the bottom of the filler neck.
3. Bleed the caliper furthest away from the actuation unit first (right front).

NOTE; The following procedure must be done at a rate not faster than 3 seconds per cycle.





4. Open the bleed nipple (1), fully depress the brake pedal, and hold down.
5. Close the bleed nipple after a minimum of one second. Release the pedal slowly. Repeat until the fluid flows freely with no air bubbles visible.

NOTE: If more than 20 cycles are required, the reservoir must be topped up.

6. Tighten the bleed nipple to 7-13 Nm (5-9.5 ft lb).
8. Bleed the remaining caliper using the same procedure.

Bleed Procedure--Rear





1. Top up the reservoir to approximately 2mm below the bottom of the filler neck.





2. Open one bleed nipple (1), fully depress the brake pedal, and hold down.
3. Switch on the ignition and wait (a minimum of 15 seconds) until the fluid flows freely with no air bubbles visible.
4. Close the bleed nipple, release the pedal slowly, switch off the ignition, and tighten the bleed nipple to 7-13 Nm (5-9.5 ft lb).
5. Bleed the remaining caliper using the same procedure.

NOTE: Ensure that the fluid level does not drop more than 10mm below the maximum mark during the above procedure.





6. After completion of the bleed process, switch on the ignition, wait until the accumulator is charged to the upper cut-out point, and top up the reservoir to the maximum level.
7. Install and tighten the filler cap.

NOTE: If the fluid level is too high, any excess fluid must be removed. This can be done by using the procedure for bleeding the rear brakes.