Vanos

VANOS is BMW’s variable valve timing system, standing for Variable Nockenwellensteuerung (variable camshaft control). It adjusts the timing of the engine’s camshafts relative to the crankshaft to optimize valve opening across different engine speeds and loads. By advancing or retarding valve timing, VANOS can improve low‑end torque, high‑RPM power, fuel efficiency, and emissions.

Operation is based on engine oil pressure. The system uses hydraulic actuators connected to the camshaft(s) and controlled by the engine control unit (ECU) through solenoids that regulate oil flow. When commanded, oil pressure drives the actuator to rotate the camshaft slightly, changing when valves open and close. There are two main variants: single VANOS, which adjusts the timing of one camshaft (typically the intake), and double VANOS, which provides independent timing adjustment for both intake and exhaust camshafts.

In some engines, VANOS works in concert with Valvetronic, BMW’s variable valve lift system, though VANOS itself is focused on timing rather than lift. The combination can further enhance efficiency and response by optimizing intake timing and, in some configurations, lift as well.

Maintenance considerations center on clean, well‑filtered engine oil, since oil quality and pressure are critical for reliable operation. Common issues include leaks around seals, worn solenoids, or sluggish actuator response, which can manifest as reduced performance, rough idle, or abnormal engine noises. Regular oil changes help preserve VANOS performance and engine longevity.