So I just changed the water pump on my 350. It ran nicely for a couple of minutes, then the new pump started squeaking. I shut down and checked things and started up and it ran then started squeaking. I shut down again, and rechecked everything I could think of, then started up, and it squeaked for a few more seconds, then quieted down. Monitored temperature, watched thermostat open, then fan come on. No squeaking. Then cooled it down for a few hours and started up again...no squeaks. Not sure why a new pump would do this, but thought I would share the experience...... If the shaft falls off I will be sure to re post!