BMW X5: Valvetrain

The valvetrain on the N52 introduced in 2006, used 5 mm valve stems on both the intake and exhaust. To increase durability, the exhaust valve stems were increased to 6 mm from 6/06 production.

All of the new NG6 engine have adopted the 6 mm valve stem for the exhaust, the intake stem remains at 5 mm.

The valves are of the "solid" type design (not Sodium filled). The diameter of the valve head is engine specific.

Camshafts

The lightweight hydroformed camshaft will still be used on the NG6 engines. Be aware that some engines may use the "cast" camshaft design. This is for supply and production reasons.

Cast and hydroformed camshafts are completely interchangeable. For example, a replacement camshaft may differ from the original. This is no problem, they will fit and work properly without any modifications.

Fig. 15: Identifying Camshaft Diameter

VANOS

The infinitely variable Bi-VANOS system is still in use on all NG6 engines. The VANOS system still retains the use of the lightweight VANOS adjusting units introduced on the N52. The only change to the system is that the N54 engine uses different spread ranges for compatibility with turbocharged engine operation.

Fig. 16: Identifying Compatibility With Turbocharged Engine Operation

NOTE: Do not mix up the intake and exhaust VANOS units. They appear similar, but have different spread ranges. Improper installation can result in valvetrain damage.

Valvetronic

The N51 and N52KP engines retain the already proven Valvetronic system from the N52. The only change for 2007 is an optimized VVT motor which has already been in production from 5/06.

The N54, on the other hand, does not use the Valvetronic system. Valvetronic is designed to reduce pumping losses and improve engine efficiency. The turbocharging system on the N54 is also designed to reduce pumping losses and increase engine efficiency.

Therefore, there is no need to have both systems on one engine. In summary, the efficiency of the N54 is gained through exhaust turbocharging and direct injection rather than Valvetronic.

Fig. 17: Identifying Injection Rather Valvetronic

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