Brake Fluid Accumulator: Service and Repair

REMOVING AND INSTALLING THE PRESSURE RESERVOIR

Removal

1. Pull off plug on the pump motor with the ignition key in position 0.




2. Completely depressurize the system. For this purpose, slowly open the bleeder valve on the lock solenoid valve and drain the brake fluid into a collection bottle.

Important: The system is under a pressure of up to 180 bar. Wear goggles and protective gloves




3. Undo the pressure reservoir (No.5). Use a universal filter wrench - e.g. Hazet 2171-2 - for this purpose.

Important: Never loosen at the filler screw X, as the gas pressure will escape abruptly in this case.


Installation

1. Screw in the pressure reservoir (No.5) with new 0-Ring (No.4) and carefully tighten it using a universal filter wrench (tightening torque 40...46 Nm; damage is possible above a torque of approx. 70 Nm).
Never turn the filler screw when installing the pressure reservoir.
Hold the pump assembly in position when tightening the pressure reservoir.

Note: Wet the seal ring with brake fluid only. Never use brake-cylinder paste. Absolute cleanliness is essential. Use only lint-free cleaning cloths.

2. Bleed the pressure reservoir and lock solenoid valve as follows:
- Open the bleeder valve on the lock solenoid valve. Push the electrical plug onto the pump with the ignition switched on. Pull off the electrical plug and close the bleeder valve as soon as the brake fluid emerges without air bubbles (use a collection bottle).
Now fully charge the pressure reservoir.
- Push on the electrical plug. As soon as the pump is heard to switch off, pull oft the electrical plug and reduce the pressure at the bleeder valve of the lock solenoid valve to zero (slowly open the bleeder valve / use a collection bottle).

Important: The system is under a pressure of up to 180 bar. Wear goggles and protective gloves.

Note: If a filling and bleeding unit is not connected, always check the level in the fluid reservoir between bleeding processes and top up with brake fluid if necessary.

3. Repeat the last process (fully charging the pressure reservoir and then reducing the reservoir pressure to zero) approx. 1-2 times (brake fluid must be free from air bubbles).




4. Bleed lock cylinder and pressure lines. For this purpose, the lock solenoid valve is pulsed with system tester 9288. The high pressure present at the solenoid valve thereby enters the pressure lines in pulses and reaches the lock cylinder via the non-return valve.

Drain oft brake fluid at the bleeder valve of the lock cylinder until no more air bubbles appear.

5. After completing the assembly and bleeding work, correct the brake fluid level - with the pressure reservoir fully charged.