How do you change the alternator on a 1997 STS?
You can get by without removing the radiator or ac condenser;
all you need to do is remove the passenger cooling fan and
disconnect the upper radiator hose and move it out of your way.
(Coolant will leak if you don't drain out about half a gallon) That
will get you access to the front bolt by the exhaust manifold
(doesn't completely remove just loosen it and leave it in the
hole). From the under side you can get to the rear bolt. I have
seen a lot of people's responses to this saying you have to take of
tons of stuff that is not necessary; so here is the list:
Remove passenger tire, inner fender and splashguard (gives
access to the lower bolts on the alternator)
Goes without saying but… disconnect your battery and remove
Under the car, remove the plastic dust cover running between the
frame rails (three 10mm bolts)
Directly under the alternator there is a small access cover
(metal) with 4 bolts; remove it.
Take the serpentine loose from the tensioner and slip it off the
Remove the passenger side motor mount from the core support.
Remove the ground from the bracket the motor mount attaches
Remove the bracket that the motor mount attaches to.
Remove the remaining bolts from the alternator on the passenger
Remove the remaining bolts form the alternator on the driver's
side (from under the car)
Slip the alternator down through the small access cover you
removed earlier. Having the pulley orientated toward the driver's
side works easiest so just rotate it till the pulley is facing the
drivers tire. (It is still a tight squeeze but it will come down;
be careful not to dent up the radiator.)
After you complete those steps just reverse them and you should
be done in about an hour and forty-five min. The first time it took
me two and a half hours to complete the entire job. Hope this helps
because there aren't many good how-to's on this make and model.