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

WARNING: The preloading on the throttle return springs increases as the rotation on the worm gear increases. Danger of injury! 
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: 

WARNING: Heed stop installation instructions.

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.

Fig 1: Installing Eccentric Shaft On Mounting Flats
G10043392Courtesy of BMW OF NORTH AMERICA, INC.

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: Checking Throttle Return Spring For Breakage
G10043393Courtesy of BMW OF NORTH AMERICA, INC.

Check that intermediate lever (1) is correctly seated.

NOTE: Illustration does not show sliding block.
Fig 3: Identifying Intermediate Lever
G10043394Courtesy of BMW OF NORTH AMERICA, INC.

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

Check that stops are securely seated.

Tightening torque: 11 37 5AZ .

Fig 4: Identifying Stop
G10043395Courtesy of BMW OF NORTH AMERICA, INC.

Stiff movement in eccentric shaft bearing is excluded.

Stiff movement can occur in worm gear.

Fig 5: Checking Eccentric Shaft Movement
G10043396Courtesy of BMW OF NORTH AMERICA, INC.

Assemble engine.