My 91 is making an awful sound on start up. I can't determine if it's the water pump or just the accessory belt. After the car warms up, I don't hear it except when I stop at a traffic light, and then it's just a little chirping sound.

Coolant level is OK. And the temp gauge is right at 12:00 after warmup.

I replaced the thermostat a few months ago and noted the sound. At the time, I thought I splashed some coolant onto the belt/pulley...OR...the water pump was cavitating. But it went away after bleeding the radiator.

Any ideas out there?