Component Tests and General Diagnostics

Checking Function of Power Steering Pump

Note: Before checking all hose connections, check pump an steering gear for leaks.

Caution: All parts must be absolutely clean! No dirt is allowed to enter the system.






(1) Pump connection
(2) Steering gear connection

Leak checking
- Disconnect pressure line from pump and connect to special tool 32 4 000 connection (2)
- Connect Special Tool 32 4 004 with banjo bolt and 2 sealing rings to special tool 32 4 000 connection (1).
- Tightening torque, refer to Specifications






Checking vane pump
1. Close valve (A).
2. Open valve (B).
3. Start engine.
4. Correct hydraulic oil level in tank. Refer to "System Bleed" at Service and Repair.
5. Heat hydraulic fluid to approx 50° C by moving the steering wheel at increased engine speed.
6. Close valve (B) for max. 10 seconds and read pressure.

If nominal pump pressure (refer to Specifications) rises to more than 10% above nominal - replace vane pump.

If pump pressure (refer to Specifications) falls to more than 10% below nominal - check Vee-belt tension. If drive-belt tension is OK, replace power steering pump.





Power-steering test
1. Open valve (B).
2. Close valve (A).
3. Start engine.
4. Pull steering wheel with force of 100 N (force meter) against left lock for about 5 seconds and read pressure.
5. Perform same step against right lock.

If pressure values are less than previously measured pump pressure, steering gear has to be replaced.

Note:
- After removal of special tool, replace seals on banjo bolts.
- Tightening torque, refer to Specifications.
- Bleed hydraulic system, refer to "Bleeding Power Steering Unit".