Disassemble

Disassemble

NOTE:
- When repairing the tandem pump, always use the repair kit of the respective manufacturer. Scrupulous cleanliness should be observed when performing any work on the tandem pump. The work should be performed on a plastic base, if possible; chamois leathers are particularly suitable for this kind of work.
- A strict standard should be applied when examining steering parts.

NOTE:
For application identification refer to "Steering : Power Steering Pump : Service and Repair : Overhaul Procedures : Application and ID" Application and ID







1. Screw down breather cap (47), take off end cover (45).
2. Screw down self-locking nut (61) of the stud bolt (46). Take off plastic sleeve (60), spring (43) and filter set (41).




3. Unscrew bolts (36) from the pump housing (2).
Take off fluid reservoir (35) and replace 0-ring (21).




4. Unscrew bolts (25) and take off bearing flange.
Examine ground face of bearing flange signs of damage.




5. Take off pressure plate (3).




6. Take off cam insert (6).
Examine ground face of pressure plate as well as sliding face of vanes on cam insert (6) for signs of scoring and wear.
There must not be any perceptible scoring present on the sliding surface of the cam insert.




7. Take locking ring (18) off the drive shaft. Replace locking ring.




8. Detach rotor (7) from the drive shaft (11) with a plastic-headed hammer and take off together with the vanes (10 off). Check the vanes (16) in the grooves of the rotor (7); they must slide easily in the rotor.
Check sliding face of vanes at cam insert for signs of wear. If necessary, repair steering pump by using the "Pump insert" repair kit.




9. Take off thrust washer (5).

NOTE: On tandem pumps (1st version) no thrust washer (5) is fitted. If, on these tandem pumps, it is found that the drive shaft does not move freely,is seized or fractured, the tandem pump must be replaced.




10. Number screw cartridges (40) consecutively from 1-4, then unscrew all 4 screw cartridges (40) from the housing with the pin wrench (010) part no. 129 589 02 07 00.




11. Check seals (39), replace if necessary. Take piston (37) and spring (38) out of the screw cartridge (40). Examine piston and piston track for signs of damage and wear. It must be possible to move the piston in the screw cartridge (40) easily and without it jamming. If this is not the case. replace the screw cartridge.




12. Knock roll pin (19) out of the housing with a suitable mandrel.




13. Take drive shaft (11) together with sleeve (15b) and bearing flange (14) out of the housing.




14. Take off sleeve (15b), check.




15. Knock out pin (17) with mandrel and take off eccentric (15a).
16. Take off thrust washer (12). check.
17. Pull bearing flange (14) off the drive shaft (11).





18. Use a screwdriver to press radial seal ring (13) out of the bearing flange.

Examine bronze bush in bearing flange for signs of damage and wear. If scoring and signs of rubbing are detectable, the bearing flange should be replaced completely.
Replace O-ring (39a).




19. Examine bearing points (arrows) of drive shaft for signs of scoring and wear.




20. Check radial seal ring (27) in the housing. If oil from the high-pressure system is found in the servo circuit or vice versa, the cause may be the radial seal ring (27).




21. Pull out radial seal ring and washer (28) with internal extractor 000 589 33 33 00. Examine bronze bush in housing (4) for signs of damage and wear, replace housing if necessary.




22. Remove locking ring (34a).

CAUTION: When removing locking ring, ensure that the housing bore is not damaged.




23. Take flow control valve (32) and compression spring (30) out of the pump housing (2).




24. Clamp flow control valve (32) in a vise at a part which is not ground and unscrew valve screw (53) of the overpressure valve. Take out sealing cone (51) and compression spring (50).
Examine the ground faces of the flow Control valve (32) and the bore in the pump housing for signs of wear and damage. If scoring is found on the sliding surfaces, the tandem pump must be replaced.

25. Check both sealing cones (high-pressure expansion hose return pipe connection). Replace misshapen seal ring cones. This is done by cutting a thread with M7 or M10 a few thread turns deep into the sealing cone. Withdraw the sealing cone from the housing with an M7 or M10 bolt.
Fit on new sealing cone in housing and press into the housing by screwing in the high-pressure expansion hose or the return pipe.