Belt squeal 4500 rpm
 

Be tried various belts, sanded pulleys with no success. Between shifts, right at 4500 rpm the belts squeal. The alt spins freely and the clutch fan works correctly. Once at highway speed well above that no issues. No a/c and air pump intact. What gives?? Thanks

Without the airpump belt, the water pump/fan pulley does not have enough grip with just the alternator belt. Assuming you have stock pulleys.

Has the belt got any fluid on it ?
Are you 100% sure the belt?

Your water pump cannot keep up with your belts acceleration.

Double belt pulley from Racing Beat!
9600 rpms no squeal ever again.
Also, you won't have to over tighten the belt. This will cause less tension and
result in longer bearing life in your alternator.
Plus your water pump will be operating at squeal speeds.
Aluminum Alternator Pulley -Double Sheave for 74-92 Rotary Engines (All) - Racing Beat

name the brand of belt that you are using.
Not all are the same,trust me.
I went through this on a couple cars.

They seem to make the belts differently and some don't actually fit into the groove correctly to run smoothly..there fore when you rev up the belt is not at 100% contact.

Not 100%, it's the belts, guess I could run it without. Misspoke earlier, meant to say no ac, but working air pump.

Ok, so with belts off, no squeal, so narrowed it down. Feels like the air pump might be it, will run without alt belt tomorrow.

It's the air pump belt, not sure I can do a dual pully. I'll try and do a new belt this weekend, thoughts on types?

have you try to tighten the belt some more? maybe it not tight enough?

I've had good luck with Gates belts.
the Gatorback belts not so much.

It may not be a belt or pulley issue, but an air pump issue. Bearings or some additional drag causing the squeal.

Picked up a new belt today and the squeal is gone. Ordered the dual pulley set up. Hope it relieves some stress on the system.

dual pulley..for what?

The double sheave from above. Not going to help air pump. But takes pressure off the water pump and alt.