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Altenator SCREEMS every time on cold start up's.. For about 15-20 seconds. Took it out, and took it to napa they tested it and said it was fine.. i dont know why its doing this??

Are you sure it's the alternator?
Make sure your belts have the right tension, if they do and they're still screaming, get a can of belt dressing, and spray your belts.

If its the belt, would it need to be tighter or looser? And would the altenator even make that noise?

When the belt starts getting old, it loosens up a little. The first symptom is normally that kind of screech for the first few seconds when you start the car. The belt needs to be at the proper tension. If you try to solve the problem only by tightening the belt, chances are it will break.
Just push on the belt with your finger, between both pulleys. Applying about 5Lbs of pressure you should have about 1/8" to 3'16" deflection.
Either way, apply the belt dressing first, and if it solves it, get ready to buy new belts.

EDIT: I'm assuming you took the alternator off the car, and took it to napa for testing. If you tested the alty inside the car, the test done means nothing. The alty can be working perfectly, but its bearings may be starting to fail, and making noise when it's cold. You need to take the alty off the car, let it cool down completely, and then take it for testing.

If this were a betting game, I'd put all my money on the belt. Get a good quality one too. On my SOHC, the belts went in this fashion. First, I tightened the crap out of them, but it wasn't solved until I replaced them.

On my BP, I had used a sketchy 90A alternator. I think it was shorting, because the charge light came on periodically when the RPM's were low (idle) and the thing didn't squeal, but a few days later my engine bay was covered in belt dust, and the belt was polished shiny (V belt alty). I replaced it with a good quality belt, and the proper alternator, set it to the proper tension, and life went smoothly.

These belts have a habit of screeming. I've found if you get any coolant on them it just makes things worse. Believe it or not most garages just use WD40. I used it liberally and it's fixed this problem for me a few times. Power steering pump can whine too in cold wheather if there's any moisture in the fluid.

The alternator belt issue is well documented on the RS model. When I had an RS I replaced my belts with the highest quality ones I could get and they squeeled like stuck pigs and then quickly failed. LOTS of other guys reported the same thing and told me to go get factory replacements from Mazda. Problem was solved.

For the record...belt dressing is not recommeded by any belt manufacturer and my personal opinion is that it is a shadetree mechanic's shortcut for a problem like this. No offense intended to those who use such a product.

To pinpoint the solution, not as a fix, belt dressing is a good idea. Even a mist of water does it.

wytbishop wrote: For the record...belt dressing is not recommeded by any belt manufacturer and my personal opinion is that it is a shadetree mechanic's shortcut for a problem like this. No offense intended to those who use such a product.

I agree. That's why I told him to get ready to buy new belts. But belt dressing is a good diagnostic tool for belt slipping problems, and a good temporary fix if you're in a bind. Of course it will NOT solve the problem. Once the belt starts to stretch, the only real solution is a new belt.
Bottom line, belt dressing, like everything else, is good if you use it properly.

About aftermarket belts screaming, I disagree. I've had 2 RS's, a '92 with gatorback belts, and a '94 (with a '95 engine) with dayco belts. Neither one ever gave me any belt trouble.

Inodoro Pereyra wrote:

wytbishop wrote: About aftermarket belts screaming, I disagree. I've had 2 RS's, a '92 with gatorback belts, and a '94 (with a '95 engine) with dayco belts. Neither one ever gave me any belt trouble.

I'm sure not every user of Goodyear or Dayco would have this problem...but many have and factory belts were the solution.