One of the biggest underhood changes that's been made over the past 20 years has been the move away from V-belts to serpentine, or multi-groove belts. It's no different with your BMW Belts. V-belts had a nasty tendency to wear quickly, and mechanics would frequently tighten them down to tightly. The result was that bearings and seals in things like the alternator and water pump wore quickly due to belt overtensioning. The serpentine belt fixed all that, though. Since they have multiple grooves, very little tension on a serpentine belt produces a great deal of friction. Accessories are easily driven by a serpentine belt with minimal wear on seals and bearings.

Your BMW belts probably consist of two or three serpentine, grooved belts running a variety of accessory functions. As long as you don't have any unusual noises coming from the belts themselves, a simple visual check of your BMW belts is all that's necessary to keep things running smoothly. If any of your BMW belts have hairline cracks or hard, glazed spots, a new belt is in order. That's all there is to it. Modern BMW belts are simple, reliable, and easy to replace, making them one of those advancements we're pleased to see on today's cars.