Valve timing drive (engine N42) — description and replacement of parts (BMW 3 Series E46)

Description

1. The N42 engine is equipped with a variable intake valve timing system known as Valvetronic. The purpose of the system is to increase engine power and efficiency, as well as reduce harmful emissions in the exhaust gases. In this system, the stroke and duration of the open state of the intake valves are regulated by an electronic device. The range of adjustment of the valve opening is quite sufficient to eliminate the need for a traditional throttle valve. In the Valvetronic system, there is an intermediate lever between the camshaft cam and the valve rocker arm, one end of which transmits movement from the cam to the rocker arm, and the other end rests on the eccentric. The eccentric shaft can be turned using a special electric motor, which is controlled by the Valvetronic electronic unit (Fig. 10.1).

Replacement of parts

Control electric motor

2. Remove the cylinder head cover (see paragraph 4).

3. Unscrew the two nuts securing the control electric motor (Fig. 10.3).





4. Rotate the motor shaft clockwise by hand and pull it back at the same time. After removing the electric motor, remove the rubber seal - replace it with a new one when installing.

5. When installing the motor, replace the seal and, rotating the motor shaft counterclockwise, push it into place until the motor housing rests against the support bracket. Secure the motor with nuts and tighten them securely.

6. Reinstall the cylinder head cover (see paragraph 4).

Eccentric shaft

7. Remove the intake camshaft as described in paragraph 11.

8. Unscrew the three bolts securing the eccentric shaft position sensor and remove the sensor (Fig. 10.8).



9. Remove the screws and remove the position sensor rotor from the end of the shaft (Fig. 10.9). The rotor is highly magnetized, so store it in a plastic bag to prevent it from attracting any metal objects.





10. Unscrew the bolt of the oil supply line nipple, unscrew the nuts securing the covers of shaft supports No.2 and 4 and remove the oil supply pipe (fig. 10.10). The covers are numbered from 1 to 4, starting from the timing chain side.



11. Unscrew the nuts of the remaining covers and remove the eccentric shaft from the supports.

12. Carefully separate and remove the needle bearing separators from the shaft journals (fig. 10.12). Do not spread the separators too wide - they can easily break.



13. If necessary, remove the liners from the supports and covers.



14. When assembling, insert new liners into the bearings and covers. Make sure that the lubrication holes in the liners and covers match (fig. 10.14).



15. Carefully separate the needle bearing separators and place them on the shaft journals.

16. Lubricate the bearings and liners with clean engine oil. Insert the eccentric shaft into the supports and install the covers in their original places. Secure the covers of supports No.1 and 3 by hand with nuts.

17. Install the oil supply pipe in place and secure the covers of supports No.2 and 4 by hand with nuts.

18. Screw in and tighten the oil inlet fitting bolt securely.

19. Make sure the support caps are installed correctly and aligned, but do not tighten them completely yet.

20. Install the sensor rotor on the end of the shaft, aligning the rotor protrusions with the slots on the end of the shaft (fig. 10.20). Insert the non-magnetic screw and tighten it to the specified torque.



21. Install the shaft position sensor and tighten it securely with the bolt.



22. Otherwise, installation is carried out in the reverse order of removal.

Intermediate levers

23. Removal and installation of intermediate levers is described in paragraph 11 as part of the procedure for removing and installing the intake camshaft. When installing the levers that worked, they must take their previous places.

Electronic control module of the system

24. On left-hand drive models, remove the battery as described in Chapter 5A. Under the battery, remove the four screws and remove the plate.

25. On right-hand drive models, the module is located in the left corner of the engine compartment, next to the electrical assembly unit. To remove the module from the bracket, pull its base away from the wing, then lift it up.

26. Disconnect the electrical connectors from the module and remove the module (fig. 10.26).



27. Installation is performed in the reverse order of removal. Please note that if a new module has been installed, it must be coded using a special BMW device. Contact your dealer or specialist.

Eccentric shaft position sensor

28. Remove the cylinder head cover (see paragraph 4).



29. Remove the three screws and remove the sensor (see fig. 10.8).

30. Installation is performed in reverse order. Securely tighten the sensor screw.