Posted on April 18th, 2012
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 consumption. 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 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 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.