11 37... Fault patterns, valve gear (N20/26/N55)
The eccentric shaft may only be twisted on the mounting flats for protection.
Risk of damage to the eccentric shaft gearing and to the servomotor worm drive.
The eccentric shaft must not spring back to the minimum stroke stop. Risk of damage!
Necessary preliminary tasks:
- Remove cylinder head cover. See 11 12 000 REMOVING AND INSTALLING/SEALING CYLINDER HEAD COVER (N55) .
- Remove ignition coil and injector shafts. See 11 12 040 REMOVING AND INSTALLING ALL IGNITION COILS AND INJECTOR WELLS (N55) .
The eccentric shaft on the mounting flats (2) must only be turned with an open-end spanner (1) for support.
The eccentric shaft has mounting flats on both sides ; if the engine is installed, the front mounting flat must be used.
Heed the following work instructions.
After the engine stops, the eccentric shaft is in the maximum stroke position.
If the actuator drive is defective, the eccentric shaft is located in an undetermined position.
Check throttle return spring (2) for breakage and correct installation position on intermediate lever (1).
Check roller cam follower (3) for correct installation position.
Check that intermediate lever (1) is correctly seated.
Check wear at stop (1) - minimum lift and maximum lift.
Check that stops are securely seated.
Tightening torque: 11 37 5AZ .
Stiff movement in eccentric shaft bearing is excluded.
Stiff movement can occur in worm gear.
Assemble engine.