Pressure Reservoir Check & Replacement Information

Checking Charging Pressure of Pressure Reservoirs

The loss of gas in the pressure reservoirs would cause a reduction in suspension volume and consequent impairment of the total spring rate. If customers file this type of complaint, the charging pressure of the pressure reservoirs must be checked.

Testing Procedures

- Bridge the two wires on the low pressure switch (located on the junction block). Turn on ignition.

- Disconnect regulating rod and operate lever on regulating switch in "discharging" direction. The oil will flow out of the pressure reservoirs into the tank in approximately 20 seconds. (The system is no longer under pressure.) If the pressure is not discharged, check regulating switch or lowering solenoid valve.

FIGURE 1:

FIGURE 2:

- Remove plug on junction block 1 and connect pressure tester (88 88 6 324 000), adapter 2 (88 88 6 343 160), and connector with hose 3 (88 88 6 372 010) (see page 9).
- Operate lever on regulating switch in "charging" direction until gauge 5 of the pressure tester displays a pressure of about 30 bar.

- Connect vent hose 3 on shut-off cock 4 of the pressure tester with a suitable container.

- Open shut-off cock slowly and observe needle of pressure tester gauge 5. The point at which the pressure suddenly drops to 0 is the gas charging pressure of the pressure reservoir.

- Recheck by repeating the test. If the charging pressure is less than 16 bar, one or both pressure reservoirs must be replaced.

To test one pressure reservoir it is necessary to clamp the flexible hose going to the other reservoir and to repeat the above mentioned pressure test.

- Remove pressure tester. Screw plug into junction block and reconnect the wires to the low pressure switch.

- Operate lever on regulating switch in "charging" direction until the high pressure switch interrupts the pump operation.

- Connect regulating rod.

Note: Discharging the system is not necessary, since it will be bled automatically with suspension movement.
Replacing Pressure Reservoirs or Spring Struts

By checking the charging pressure, it can be determined which pressure reservoir has to be replaced.

If the car has been operated more than 40,000 miles and a pressure reservoir is defective, it is recommended to replace both pressure reservoirs. This also applies to the replacement of the spring struts.

Procedure

a) Discharge pressure in line system.

b) Remove and install pressure reservoir or spring strut.

c) Charge line system to minimum pressure.

Note:
The system does not have to be bled after completion of repairs.