Timing belt makes a bit of a whine, and it also drives the water
pump. Alternator, power steering pump, a/c compressor can make
a variety of noises, and the serpentine belt has been known to
make swishing or squealing noises. You can remove the serpentine
belt and run the engine without the external accessories as a
diagnostic. This will tell you if it is internal or external
and give you an opportunity to inspect individual devices for
loose or dry bearings, worn pulleys, etc.
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