Belt tension? Snapped a Gatorback on the alternator

Kind of been a browser and not much of a poster until now

The belts in my 2000 ES were getting cracked so I replaced both with Gatorback. They were good for about 3 days and started squealing so I re-tensioned and they were good, again.

Preface: I'm not a pro but I'm not an idiot (usually)

Belts started squealing again and I re-tensioned. They were pretty tight - following the 90 degree twist rule I read about in another thread. Today, the alternator/water pump belt (Gatorback P/N 4040360) snapped clean through. Of course, this is after it squealed for a good 5 minutes straight.

Pulleys look aligned correctly. There's no excess wear on the edges of the belt, and the previous belts (no idea on the brand) had zero difficulties so I don't think it's an alignment thing.

Anybody else have this happen?

Currently, it's sporting a Goodyear non-Gatorback, 360K4, but started squealing again within ~5 minutes of real driving, after the initial bed -> retension period.

Kind of out of ideas. Both water pump and alternator spin freely without binding.

Mine did the same thing but my alternator pulley was the culprate, it felt like it spun freely when it was on the car but when i took it off and put next to my ear you could hear scraping each full turn in the same spot which means the bearing was bad. If your water pump was bad ud most likely be leaking out coolant since its bearing is also a seal. Kinda sounds like ur in the same boat.

Hmmm - good point. I take a dowel rod and use it as a stethoscope on my pickup truck for diagnosing accessory issues but haven't on the Protege yet. However, I did listen really carefully and didn't hear even a minor scraping when spinning the accessories.

Water pump looks OK, no leaking from it. How difficult are those to replace if/when they go, and are they common?

Just an update...

Been running the new non-Gatorback belt (still a Goodyear) on the alternator and water pump with less difficulty. Still get squeals but only at idle, and only with both vent fan and lights on - fine with just one or the other. Being as though the Gatorback snapped, I've been reluctant to tighten the new Goodyear belt without a tension gauge.