11 37 020 Removing and installing/replacing servomotor for eccentric shaft (N20)

Special tools required: 

• 11 7 170 .

Necessary preliminary work: 

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

The eccentric shaft on the mounting flats (1) must only be turned with an open-end spanner (2) 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 On Mounting Flats

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If the actuator drive is defective, the eccentric shaft is located in an undetermined position.

Release screw (1) at oil spray nozzle (2).

Tightening torque: 11 37 4AZ .

Unclip oil spray nozzle (2) from the bracket on the actuator drive (3) in direction of arrow.

Fig 2: Identifying Oil Spray Nozzle, Bolt, And Bracket

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Turn 4-mm hexagon socket wrench (2) clockwise (maximum stroke).

Secure eccentric shaft (1) with open-end spanner (3) for support.

Fix eccentric shaft with an open-end spanner (3) (kickback danger)

Fig 3: Securing Eccentric Shaft And Adjusting Via Servomotor Using 4mm Hexagon Socket Wrench

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Position eccentric shaft in the middle between maximum stroke and minimum stroke.

Secure eccentric shaft (1) with special tool 11 7 170 .

The open-end spanner can now be removed.

Fig 4: Identifying Worm Gear

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Remove minimum stroke stop (1).

Stop (2) of maximum stroke must remain in place for support of the intermediate shaft.

Tightening torque: 11 37 5AZ .

Fig 5: Identifying Minimum Stroke Stop And Maximum Stroke Stop

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Slowly adjust eccentric shaft to minimum stroke via servomotor using 4-mm hexagon socket wrench (2) and open-end spanner (3).

Release gearing of the eccentric shaft from worm drive.

Fig 6: Securing Eccentric Shaft And Adjusting Via Servomotor Using 4mm Hexagon Socket Wrench

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Turn eccentric shaft (2) approximately 90° further with an open-end spanner (1).

Secure eccentric shaft (2) against kickback with the assistance of a second person.

Graphic N55.

Fig 7: Turning Eccentric Shaft Using Open-End Spanner

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Position stop (1) of eccentric shaft at stop of maximum stroke.

Fig 8: Positioning Stop Of Eccentric Shaft At Stop Of Maximum Stroke

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Screw in stop (1) for minimum stroke.

Tightening torque: 11 37 5AZ .

Installation note: 

The eccentric shaft is now secured and can no longer kick back.

Fig 9: Identifying Stop For Minimum Stroke

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Release screws (1).

Fig 10: Identifying Screws

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Turn servomotor (1) in direction of arrow and remove upwards.

Installation note: 

Clean blind holes with compressed air.

The gearing of the worm gear and the eccentric shaft must be greased with LONGTIME PD 1 (4.1) .

Fig 11: Turning And Removing Servomotor

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Insert bolts (1).

Tightening torque: 11 37 3AZ .

Installation note: 

Eccentric shaft and worm drive must now be joined.

Fig 12: Identifying Screws

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Release stop (1) of minimum stroke of eccentric shaft.

Tightening torque: 11 37 5AZ .

Fig 13: Identifying Stop For Minimum Stroke

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Installation note: 

Carefully mate eccentric shaft gear in the worm shaft of the servomotor by turning the actuator drive.

Fix eccentric shaft with an open-end spanner (3) for support and secure (kickback danger).

Fig 14: Securing Eccentric Shaft And Adjusting Via Servomotor Using 4mm Hexagon Socket Wrench

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Centrally clamp the eccentric shaft with a 4-mm hexagon socket wrench (2) at the servomotor.

Secure eccentric shaft (1) with special tool 11 7 170 .

Fig 15: Identifying Worm Gear

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Screw in stop (1) for minimum stroke.

Tightening torque: 11 37 5AZ .

Fig 16: Identifying Minimum Stroke Stop And Maximum Stroke Stop

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Slowly adjust eccentric shaft (1) to maximum stroke via servomotor using 4- mm hexagon socket wrench (2) and open-end spanner (3).

Fig 17: Securing Eccentric Shaft And Adjusting Via Servomotor Using 4mm Hexagon Socket Wrench

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Retract oil spray nozzle (2) on actuator drive (3).

Engage bolt (1) and release back to 90°.

For exact positioning of the oil spray nozzle (2) audibly clip it in at the top.

Secure oil spray nozzle (2) with screw (1).

Tightening torque: 11 37 4AZ .

Fig 18: Identifying Oil Spray Nozzle, Bolt, And Bracket

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Remove all special tools.

Assemble engine.

Check function of DME.

• Service function.
• Drive.
• Digital Motor Electronics
• Valvetronic run-in procedure.