A squeaky alternator is sometimes a sign that the fan belt or something associated with it is squeaking, not the alternator. (Possibly the belt or belt tensioner) So first I'd make sure it's actually the alternator squeaking before I proceeded. You could try some belt dressing on the belt and see if that helps or changes the squeak. If however it is the alternator, that's usually a sign the bearing's gone out and you will need to replace the alternator.
Either the belt is worn out or the tensioner is defective.
oil it or shoot a squealer
depends on where the "squeaky sounds" are coming from. something could be loose, such as a hinge or something. if it screams like a banshee, then its the alternator belt, or the alternator itself. it all just depends on where its coming from
slipping alternator/power steering/ auxillary drive belt
A squeaky belt is usually caused by a bad belt, a missaligned pulley, or something leaking on the belt.
Assuming the belt and pulleys are in good shape, put a dab of clear silicone grease on both sides of the belt. Do this with the engine off. Squeak is gone.
First, you need to inspect the belt for cracks and defects. Also make sure that the belt is still flexible. If it does not have any problems, use tension bolt to tighten the belt.
With engine off try putting a small dab of silicone grease on each side of the belt. It works for me.
alternator drive belt?
Loosen the alternator tensioner bolt. The alternator belt will become loose. Remove the alternator belt. Put the new alternator belt on and reverse the process.
I would bring it in to a car shop because my family has had problems and it has been from the motor, to the belt, to the steering axle.