BMW VANOS System-Service and Rebuild
What's a Vanos?
Vanos is BMW's name for its engine variable valve timing unit. Variable valve timing is a way of modifying the engine intake and /or exhaust valve opening/closing timing dynamically to provide improved engine performance.
What are the symptoms of a failing Vanos?
Overall loss of torque and power, particularly in the lower RPM range,<3k. Bogging then surging at 3K RPM. Uneven power distribution and RPM transition. Engine hesitations in the lower RPM range, <3k. Louder idle and intermittent idle RPM hiccups. Difficult takeoffs. Loss of power and bogging when AC on. Increased fuel composition. Double Vanos cars with the M52TU engine (98/99-00) experience cold weather cold start idle jolts and possible stall.
What are the benefits of repairing the Vanos?
Overall increase in torque and power, particularly in the lower RPM range <3k. Resolution of bogging then surging at 3k RPM. Smooth even distribution of power and RPM transition. Resolution of engine hesitations in the lower RPM. Smooth even distribution of power and RPM transition. Resolution of engine hesitations in the lower RPM range, <3k. Quiet stable idle. Smooth easy takeoffs. Improved performance when AC on. Reduced fuel consumption, by ~10%. Resolution of double Vanos M52TU engine (98/99-00) cold weather cold start idle jolts and possible stall.
Is there a good solution to the Vanos problem?
To correctly address the Vanos problem the piston O-rings need to be replaced with O-rings need to be replaced with O-rings made from higher grade material. We do need the car for a good part of the day, but will provide you with a complimentary loaner car. It's prudent to change the valve cover gaskets during this repair since no added labor time is needed. You'll be returned a BMW which has it's "Vroooom" back, and is a joy to drive again.