Twice in about a month, my engine alternator/water pump belt has squealed
on start up...ceasing to make the noise after just a slight blip of the
throttle.   I think this  happened  both times when I've forgotten and left
on the headlight, then started the van from there.  I could be wrong on this
though.

  This van is inline four powered.  It has a single V-belt driving the
alternator, the WP...no power accessories at all.   The belt tension seems
just right and the belt is fairly new and is not contaminated by spilled
fluids.  The alternator and the Water Pump bearings feel normal...I can
detect no play or bearing problems.  I'm reluctant to simply add some
tension to the belt...too tight is hard on the bearings.

  So, is it somehow related to a larger electrical load, due to the
headlights being left turned on,  that causes this squealing at
startup?...This morning when this happened it was cool.  I jumped out and
went round to the pulleys behind the license plate door and confirmed that
all seemed to be turning normally, even though this squeal was
happening....Then, a short blip on the throttle and all went quiet.

  I am getting set to take a 1500 mile commute into the back country of the
west, so I am trying to do my pre-trip stuff.  I have a spare belt and a
spare water pump...no spare alternator, but this one is rebuilt and has a
recent Voltage Regulator replacement.   Should I just slightly tighten the
belt...

  Any opinions?

  Don Hanson