Oil Pump: Service and Repair

WM 172019 Removing and installing oil pump on 4.8-litre DFI engines

Technical values





Preliminary work

Information

If vehicles have fault entries relating to oil pressure, oil pump activation, oil pressure monitoring, etc. in the DME control unit (and a warning light comes "on" on the instrument cluster), proceed as follows:

- Check the oil level.

- Delete related faults.

- Do not replace components, such as the oil pump, oil pressure sensor or oil pressure control valve if you suspect that they are faulty.

If the vehicle has not been driven for a long time (months), the control mechanism in the oil pump can become stiff ("stick").

Very short trips and a lot of loading/manoeuvring can cause the oil to become very diluted => Oil pressure very low. For example, 20 cold starts in quick succession can reduce the viscosity of the engine oil by 30%.

- Change the engine oil. Test-drive the vehicle.

- If error messages/warnings are displayed again, proceed in accordance with the instructions under Guided Fault Finding in the PIWIS Tester.

1. Remove oil pan and oil guide housing. -> 175019 Removing and installing oil pan and oil guide housing on 4.8-litre DFI engines - section on "Removing" Service and Repair

Information

Component overview

Information

- The oil pump must not be disassembled and reassembled.

- When carrying out work on the oil circuit, it must be ensured that no dirt gets into the engine.

Information

- The oil pump can be replaced while installed.





Oil lines, intake manifold on turbo engine M48/51









Oil lines, intake manifold on naturally aspirated engine M48/01









Oil pump on turbo engine M48/51 with oil extraction stage









Oil pump on naturally aspirated engine M48/01






Removing oil pump

1. Disconnect lines at the oil pump.
1.1. Remove screw on oil return line (vent line). -1-





Oil return

1.2. Remove the two screws on the intake manifold and take the intake manifold off the oil pump. -3-
2. Remove the sprocket cover for the oil pump
2.1. Loosen the top screw -1- using an open-ended wrench until the sprocket cover is released. Remove the two remaining screws. -2 and 3-





Sprocket cover mounting

2.2. Pull the sprocket cover down and off. The top hole is open. => Top threaded joint on sprocket cover





Top threaded joint on sprocket cover

3. Remove the oil pump drive sprocket.
3.1. Position vibration balancer with screw tightened hand-tight on the crankshaft stub. Push on change-over ratchet. => Screw on sprocket





Screw on sprocket

3.2. Loosen screw on sprocket. Use an extension if necessary because the screw is very tight -1-. Counter at the vibration balancer using the change-over ratchet. The loosened screw must not be re-used.
4. Press off small tensioning rail on the chain -arrow- using a screwdriver => Oil pump drive chain and remove the sprocket from the pump. Loosen the tensioning rail slowly. The chain remains fitted.





Oil pump drive chain

5. Remove oil pump
5.1. Unscrew screws on the oil pump -2-. Hold the oil pump securely.





Oil pump screws

5.2. Carefully loosen the locking hook on the joining socket using a screwdriver => Disconnecting pipe and carefully remove the oil pump under the vent line.





Disconnecting pipe

Installing oil pump

1. Fit the oil pump
1.1. Lubricate sealing rings on joining socket -5- with lubricant 000 043 204 68 (status 05/07)





Oil guide (oil plate)

1.2. Carefully guide oil pump under the oil return line (vent line) and move into installation position.
1.3. Connect oil pump and joining socket together. The locking mechanism must clip in (on socket fitted in the oil pump).
1.4. Fit three screws on the oil pump -2-.





Oil pump screws

1.5. Screw oil return line (vent line) to the oil pump. -1- => Tightening torque: 10 Nm (7.5 ftlb.)
1.6. Screw intake pipe to the oil pump. -3- => Tightening torque: 12 Nm (9 ftlb.)
1.7. Tighten three screws on the oil pump. -2- => Tightening torque: 13 Nm (9.5 ftlb.)
2. Press off small tensioning rail on chain -arrow- using a screwdriver => Oil pump drive chain , insert sprocket and fit it on the pump. Insert new screw and screw it in hand-tight.





Oil pump drive chain

3. Fit the oil pump drive sprocket.
3.1. Position vibration balancer with screw tightened hand-tight on the crankshaft stub => Sprocket screw. Push on change-over ratchet.





Sprocket screw

3.2. Fit screw on sprocket. Use an extension if necessary due to the very high tightening torque -1-. Counter at the vibration balancer using the change-over ratchet. Tighten the screw in two stages. => Initial tightening: 20 Nm (15 ftlb.) ; final tightening (torque angle) => Torque angle: 90°
4. Fit oil pump sprocket cover.
4.1. Slide in sprocket cover in an upward direction. The top hole is open. Screw is still fitted, but loosened. => Top threaded joint on sprocket cover





Top threaded joint on sprocket cover

4.2. Tighten the top screw -1- using an open-ended wrench (tighten slightly by hand). Fit the two remaining screws. -2 and 3-





Sprocket cover mounting

5. Check that the tensioning rail and drive chain are positioned correctly.

Subsequent work

1. Install oil pan and oil guide housing. -> 175019 Removing and installing oil pan and oil guide housing on 4.8-litre DFI engines - section on "Installing" Service and Repair