Disassembly - Components: Valvetronic: Notes

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The Valvetronic system simultaneously varies the valve opening time and the intake valve opening lift between 0.3 mm and 9.85 mm, according to engine speed and load. This means that the air volume is controlled according to engine requirements. The valve gear is essentially the same as the N62 engine and has been adapted to the geometry of the N73 (with two more cylinders).

* Modifications have been made to these components making them different from the N62.

NOTE: To remove the cylinder head, it is necessary to remove the variable valve gear and eccentric shaft in order to gain access to the cylinder head bolts.

Fig 1: Identifying Valvetronic Components

Courtesy of BMW OF NORTH AMERICA, INC.

The Valvetronic motor is rubber mounted at the rear (1 lower left) to isolate it from the cylinder head cover. The Valvetronic motor is secured to the bridge support by the intermediate flange and has a hexagon drive (2 lower left), which engages into the intermediate shaft (7 lower right).

The intermediate shaft is mounted in the bridge support and is engaged by its spindle in the eccentric shaft teeth. This design provides ease of removal if the motor/gear fails.

Fig 2: Identifying Intermediate Shaft (7)

Courtesy of BMW OF NORTH AMERICA, INC.

To remove the intermediate shaft, use the spanner tool #90 88 6 11 7 270 to unthread the locking collar (lower left). If you remove the outer snap ring (as shown lower right), the tensioning drive washer can be removed along with the tensioning ring behind it.

Fig 3: Removing Outer Snap Ring

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: When reinstalling the tension ring and tensioning drive washer, the ring eyelet must engage with the pin:

On the drive washer (1)
and
In the intermediate shaft (2)
Test fit (insert) the Valvetronic motor hex shaft.

If it does not insert easily, remove the drive washer and flip the tension ring over to reassemble.

Fig 4: Identifying Intermediate Shaft And Drive Washer
Courtesy of BMW OF NORTH AMERICA, INC.
Remove torque compensation spring and Valvetronic bridge support assembly as per the Repair Instructions (N62 section can be used) .
Remove bank 1 - 6 cylinder head.