Basic Function BMW VANOS System

VANOS for timing was used beginning in 1994 with a single VANOS. 

The VANOS has the ability to adjust the valve timing which improves the engine power dynamics and reduces the tailpipe emissions. It optimizes the camshaft angle for all ranges of the engine operation, as both intake camshafts, and exhaust camshafts are continuously adjusted to the optimum.

Here are just some of the benefits of the VANOS.

• It increases torque at lower to mid range engine speeds with no loss of power in the upper range engine speeds.
• It allows for increased fuel economy due to optimized valve timing angles, and reduced emissions.
• You enjoy a smoother idle quality due to optimized valve overlap. (Who could have guessed)!

The engine control module activates the VANOS solenoid valve based on the particular DME program mapping. Then hydraulics kick in and directs the flow of the engine oil. The controlled oil flow acts on the mechanical component of the VANOS to position the camshafts.

You may wonder why we showed the internal parts of a VANOS; note the small seals or o-rings in that photo. When one or more of those become fatigued with age, they begin leaking oil. So, if someone tells you that you have a leak in the VANOS, and you cannot begin to understand what that is all about, (because it looks like just one big heavy hunk of steel), now you know! It will be an internal leak that will affect the engine’s performance. You will probably not see any oil at the VANOS or drips as expected.