Well, I'm having trouble hearing it from here, so I'm going to have to guess. The radiator fan is electric, and only runs when needed. They usually howl, but only when it runs, or possibly at highway speeds because the wind makes it spin. There are bearings in the water pump, alternator, power steering pump, and belt tensioner pulleys.
Your mechanic will start by listening with a stethoscope. He might also remove the serpentine belt, then spin the various pulleys by hand. If none seem noisy, he will run the engine with the belt removed. If the whine is still there, suspect the water pump, depending on which engine you have, (you didn't say). On some engines, the water pump is driven by the back of the timing belt, and is not easily accessible for inspection.
The most common culprits of a whine that changes pitch with engine speed are the bearings in the idler pulleys for the serpentine belt. They often don't feel bad when spinning them by hand, so the stethoscope is the best way to tell.
caradiodoc
Dec 6, 2009 at 2:36 AM
