11 37... Fault patterns, valve gear (N20/N55)

Necessary preliminary tasks: 

• Remove CYLINDER HEAD COVER .
• Remove IGNITION COIL AND INJECTOR SHAFTS .

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.

Fig 1: Turning Eccentric Shaft Using Open-End Spanner

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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.

Fig 2: Identifying Throttle Return Spring, Intermediate Lever, And Roller Cam Follower

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Check that intermediate lever (1) is correctly seated.

Fig 3: Identifying Intermediate Lever

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Check wear at stop (1) - minimum lift and maximum lift.

Check that stops are securely seated.

Tightening torque: 11 37 5AZ .

Fig 4: Identifying Intermediate Lever Stop

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Stiff movement in eccentric shaft bearing is excluded.

Stiff movement can occur in worm gear.

Fig 5: Identifying Worm Gear

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Assemble engine.