I am unsure of the name of the belt, but it's the one on the far right side of the engine, and is located right on top.

I put wax on it and it stops sqeaking for a while, but starts again.

This happened before and I let it go, then it broke. Don't wanna let that happen again!

So what should I do, tighten or loosen?

tighten it

Does it really squeek when loose? How is that possible?

Ok, i'll do that tomorrow.

If you overtighten the belt it will squeek and fly off . Have about half inch of slack when you push on the belt on top.

Don't use the wax, replace the old belt with a new on and tighten as Racer1 stated. They also tend to sqeak when wet/after the rain or a washing.

Well, it IS a new belt! I had the old one replaced when it broke and it was fine for around 1-2 months, now it's sqeaking again. I don't know why!

I only use the wax to temp. stop the sqeaking until I can tighten it.

My new belt sqeeked until I tightened it as well. Bet they all do as they "break in". I just loosen the bottom alternator bolt and wedge my three foot crow bar behind it and pull back on it and tighten the bolt when I've brought the alternator back some. Works for me!

I've found it's almost impossible to overtighten the alternator belt on the 2.8. Maybe two people could do it, but it's hard to hold pressure on it and tighten the bolt at the same time. Don't use belt spray, wax or any kind of lube on the serpentine belt. The only quick fix without causing the noise to keep gettig worse is a shot of baby powder on it once in awhile.

I do the same also on my 84, i use a crowbar, and jam it in front of the alternator pull it back as hard as i can, and tighten the little bolt. They only squeal when its loose, slipping.

Look if you have any oil leaks near the oilpan, or timing cover, if there is, it is possible to get on the belt and decompose it, after a while, you will be driving and your belt breaks on you.