Bill:
As I suggested in my other post, I would guess that you had/have the belt that
drives the alternator slipping. Once the battery is fully charged, it doesn't
take much current to keep the battery charged and the alternator is not required
to put out much current. As more and more electricity is demanded from the
alternator, the harder it is for the engine to spin it and the more likely it is
for the belt to start slipping. As an experiment, leave the engine at an idle
and start turning on every electrical device you can. Sometimes, if everything
is turned on, the belt will start slipping as the alternator needs to put out
more current, and when it does, you will get this metalic squeal. What you would
most likely be hearing is the belt slipping against the stamped metal pulley of
the alternator. It is reminisant of the fingernails on the chalkboard, but more
metalic in sound. If that should happen, you know that the belt is glazed and
either needs cleaning, a belt dressing, or replacement.
Blake
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