Tandem pump models 67, 167 - RA46C97650730X (C.)
| Vent cap (35c) and end cover (35d) | Follow note for models 129 and 140. remove, install (numbers 1 and 43). |
| Self-locking nut (35e) | remove, replace, screw on (numbers 2 and 43). |
| Plastic sleeve (35f), spring (35g) and filter set (35h) | remove, install (numbers 2 and 43). |
| Reservoir (35) | disassemble, assemble. Unscrew, screw on reservoir, 8 Nm. Replace O-ring (2g) (numbers 3 and 42). |
| screws M8 (4b) | 4 unscrew, screw on, 25 Nm. Detach, attach pump housing (2), numbers 4 and 39). |
| O-ring (4h) in bearing flange | check, replace if required (numbers 5 and 38). |
| Pressure plate (8) | remove, install, check O-ring (8a) and shaped wedge (8b), replace if required (numbers 5 and 38). |
| Cam insert (6) and straight pins (6a) | remove, check, install, note installed position (numbers 6 and 37). |
| Locking ring (11a) | remove, replace, install (numbers 7 and 34). |
| Rotor (7) and vanes (7a) | remove, check, install and repair if required. Note installed position (numbers 7 and 33). |
| Drive shaft (11) | withdraw from bearing flange, check for wear, replace if required, install (numbers 8-10 and 30-32, note version). |
| 8 screws M6 (4c) | unscrew, screw in 10 Nm. Remove, install bearing flange cap (4a). Check radial seal ring (4d), replace if required (numbers 10 and 32). |
| Bearing sleeve (5f) and bearing shell (5g) | remove, check, replace O-ring (5a), install (numbers 11 and 29). |
| Piston (5c) and piston springs (5d) | remove, check for wear and damage, install. Follow note (numbers 12 and 27). |
| Spacer washer (5h) | remove, install (numbers 13 and 26). |
| Piston support ring (5) | remove from, press into bearing flange housing (4) (number 14). Note manufacturer-related (number 25). Replace O-rings (5b). |
| O-ring (4f) and shaped wedge (4g) | replace in bearing flange housing (4) (numbers 16 and 24). |
| Radial seal ring (4e) | check, replace if required (17 and 23). |
| Flow control valve (2c) | disassemble, check, assemble, replace tandem pump if required (numbers 18, 19 and 21, 22). When removing the locking ring, ensure that the housing bore is not damaged. Check the ground surfaces of the flow control valve (2c) and the bore in the pump housing for wear and damage. If scores are found on the sliding surfaces, the tandem pump must be replaced . |
| After installing the tandem pump | fill or bleed systems (Filling and bleeding the power steering pump/tandem pump ) and check for operation and leaks. |
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.
A strict standard should be applied when examining steering parts.
Special tools
Disassembling
Note models 129.066/067, 140.04/050/051
On the above models the oil reservoir (35) is attached to a support (1a) which is screwed to the tandem pump (1).
Loosen hose clamp, disconnect hose (arrow) and set aside. Unscrew bolts (46) and remove tandem pump (1) from support (1a).
Unscrew bolts (arrow, 4 bolts). Remove end cover (2k), check O-ring (2g), replace if required. Work steps numbers 1-3 are omitted.
Note - models 129.076, 140.056/057
The tandem pump (1) for engine 120 has an expansion reservoir for equalizing the oil reservoir (35) on the pump housing which is located between the coolant thermostat and the intake pipe.
An oil dipstick (36a) with min. and max. markings for the oil level check is located on the end cover of the expansion reservoir (36).
Unscrew the four bolts (35a) from the oil reservoir (35) and remove reservoir. Check O-ring (2g), replace if required. Work steps numbers 1-3 are omitted.
- Screw down vent cap (35c), remove end cover (35d).
- Unscrew self-locking nut (35e) down from the stud bolt (35i). Remove plastic sleeve (35f), spring (35g) and filter set (35h).
- Unscrew bolts (35a, 4 bolts) in oil reservoir. Remove oil reservoir (35) and check O-ring (2g), replace if required.
- Unscrew bolts (4b) in bearing flange (4) and remove pump housing (2).
- Remove O-ring (4h) in bearing flange (4), check, replace if required.
Remove pressure plate (8).
Check seal (8a) and shaped wedge (8b), replace if required.
- Remove cam insert (6) and straight pins (6a). Check ground surface of pressure plate as well as the sliding surface of the vanes on the cam insert for scores and wear.
There must be no detectable scores on the sliding surface of the cam insert.
- Remove locking ring (11a) from drive shaft (11). Replace locking ring. Detach rotor (7) from drive shaft (11) using a plastic hammer and remove all vanes (7a, 10 vanes).
Check the vanes (7a) in the grooves of the rotor (7); they must slide easily in the rotor. Check sliding surface of vanes on cam insert for wear. If required, repair power steering pump using the "pump insert" repair kit.
- ZF
: Withdraw drive shaft (11) from bearing flange (4).
Vickers/LUK : First carry out item 10 and remove drive shaft with bearing flange cap.
- Check drive shaft for scores and wear at the bearing points (arrow), replace if required.
- Unscrew bolts, 8 pieces M6, (4c) and remove bearing flange cap (4a).
Check radial seal ring (4d), replace if required.
- Replace O-ring (5a).
ZF : Remove bearing sleeve (5f) and bearing shell (5g), check, replace if required.
Vickers/LUK : Detach snap ring from drive shaft, remove the additional built-in washer and bearing sleeve (5f) with bearing shell (5g).
- Withdraw piston (5c) and piston springs (5d). Check piston and piston track for wear and damage, replace if required.NOTE: The piston must slide easily and without high spots in the housing. If this is not the case, the piston, piston springs and piston support ring (5) must be replaced.
- Remove spacer washer (5h) in the case of the ZF tandem pump.
- Tap bearing flange housing (4) between two blocks of wood until the piston support ring (5) can be removed.
- Replace O-rings (5b).
- Replace O-ring (4f) and shaped wedge (4g) in housing.
Check radial seal ring (4e), replace if required.
NOTE: If oil escapes from the servo circuit to the level circuit or vice versa, the cause is in the radial seal ring (4e). - Withdraw radial seal ring (4e) with internal extractor 000 589 33 33 00. Check bronze bush in housing (4) for damage and wear, replace if required.
- Remove flow control valve (2c) and compression spring (2j) from pump housing (2).
When removing the locking ring (2a), ensure that the housing bore is not damaged.
- Clamp flow control valve (2c) in the vise at an unground section and unscrew the valve screw (2e) of the pressure relief valve.
Remove sealing cone (2f) and sealing cone compression spring (2d).
Check the ground surfaces of the flow control valve (2c) and the bore in the pump housing for wear and damage. If scores are found on the sliding surfaces the tandem pump must be replaced .
- Check both sealing cones (high pressure expansion hose, return pipe connection). Replace deformed sealing cone. For this step, cut a thread in the sealing cones a few thread turns deep with M7 or M10. Withdraw the sealing cones from the housing with a M7 or M10 screw.
Insert new sealing cones in housing and press into the housing by screwing the high pressure expansion hose or the return pipe into the housing.
Fig 25: Identifying Flow Control Valve (2c), Valve Screw (2e), Sealing Cone (2f) And Compression Spring (2d)Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Assembly
NOTE: Before assembly, lubricate all parts with oil.Replace all O-rings.
With a new flow control valve, ensure that the pressure relief valve is at the correct opening pressure..
- Clamp flow control valve (2c) in the vise at an unground section.
Insert sealing cone compression spring (2d) and sealing cone (2f) and screw on valve screw (2e). The valve must slide easily in the housing bore.
- Insert compression spring (2j) and flow control valve (2c) in pump housing (2).
- Press radial seal ring (4e) up to the stop using a suitable mandrel (arrow).
- Insert O-ring (4f) and shaped wedge (g) in bearing flange.
- Place O-ring (5b) around piston support ring (5).
Mounting ZF piston support ring :
Press piston support ring (5) into bearing flange housing (2).
Ensure that centering pin (5e) is exactly above the centering bore (arrow).
Mounting Vickers/LUK piston support ring :
Before inserting the piston support ring with the drive shaft, pre-assemble as follows:
- Insert piston spring (5d) and piston (5c) in piston support ring (refer to number 27).
- Insert bearing shell (5g) (refer to number 28).
- Insert bearing sleeve (5f).
- Insert drive shaft (11) in bearing flange cover (refer to number 30).
- Push drive shaft into the bearing sleeve/bearing shell (5g, 5f). Mount locking ring.
- Insert piston support ring with drive shaft in the pump housing (refer to number 31).
- ZF: Insert spacer washer (5h).
- Insert piston spring (5d) and piston (5c) in piston support ring.
- Place bearing shell (5g) diagonally in front of two pistons.
Carefully press remaining pistons together in the piston support ring using an Allen wrench or similar tool, whilst pressing the bearing shells using the fingers.
Mount O-ring (5a).
- Insert bearing sleeve (5f) in bearing shell (5g).
Insert side milled on both sides upwards.
- Push drive shaft (11) through radial seal ring (4d) in bearing flange cap (4a).
- Insert drive shaft (11) with bearing flange cap (4a) into pump housing (2a). At the same time turn shaft carefully until the eccentric (arrow) of the drive shaft can be pushed into the bearing sleeve (5f).
- Fasten bearing flange cap (4a) with 8 screws M6 (4c).
Tightening torque: 10 Nm.
- Push rotor onto the drive shaft so that the chamfer on the inside diameter (arrow) points towards bearing flange cap (4a).
- Mount new locking ring (11a). The locking ring must seat correctly in the groove (arrow) of the drive shaft.
- Insert vanes (7a, 10 vanes) in the rotor (7). Insert vanes with the rounded, metallic glossy sides towards the cam insert in the rotor.
- Insert straight pins (6a) with the punched end (arrow) in the bores of the cam insert (6) so that they project on both sides of the cam insert.
- Insert cam insert (6) with direction of rotation arrow upwards on the bearing flange (4). At the same time the straight pins (6a) must be above the centering bores (arrow).
- Insert seal (8a) and shaped wedge (8b) in pressure plate (8).
Mount pressure plate (8) with the ground surface towards the cam insert.
Insert O-ring (4h) in bearing flange (4).
- Insert bearing flange (4) in pump housing (2) and fasten with 4 bolts M8 (4b).
Tightening torque 25 Nm.
Note models 129.066/067, 140.04/050/051
Insert O-ring (2g) mount end cover (2k) and tighten with four bolts (arrow).
Tightening torque: 8 Nm
Screw tandem pump (1) onto support (1a) with bolts (46). Screw on oil hose (arrow).
Work step number 40 is omitted.
Note models 129.076, 140.056/057
Insert O-ring (2g), screw on oil reservoir (35) with bolts (35a).
Tightening torque: 8 Nm
Work step number 40 is omitted.
- Insert O-ring (2g), mount reservoir (35) on pump housing and screw on with bolts (35a, 4 bolts).
Tightening torque: 8 Nm
Insert filter package (35h) and spring (35g), compress slightly and tighten with new selflocking nut (35e).
Mount end cover (35d) and screw on bleed cap (35c).
After installing the tandem pump (operation no. 46-0710), fill or bleed systems (40-0715).
Check tandem pump for operation and leaks, connect pressure gauge if required and check pump pressure (operation no. 46-3070).