Water pump making chirping noise

[exbass94]

The Explorer has been making a weird squealing/chirping noise lately. At idle, it would make a small chirp every few seconds. If you step on the gas, the chirping inscreases to where it's basically a constant squeal. (This is NOT the belt squealing, I know what that sounds like) It's kind of intermittent, where it can be totally quiet for 5 minutes, and then come back for the next 5 minutes. I replaced the idler pulley, thinking/hoping that was it and it wasn't. The tensioner assembly and the belt are about 4 months old. I used a rubber hose as a stethoscope and it's definitely coming from the water pump. I didn't notice any play in the pulley.

It just seems like kind of an unusual problem. I searched a lot and couldn't find anything about water pumps making a chirping noise. I'm gonna drag my ass out of bed early tomorrow (9:00 ) and put a new water pump in...