Squeaking sound on slight inclines?..water pump?

[tbcaddy18]

I have a 1986 FWB (RWD) 307 with 153,000 miles, and I have noticed that as of lately when the engine reaches operating temperature and I start climbing slight inclines I hear a squeaking noise when pressing the accelerator. I haven't ever changed the water pump in my time owning it which is a little over 6 years.

This only happens when increasing mileage/speeding up...once I reach my desired speed and stay at it, the noise stops....and only after the engine temperature is up, say around 20 minutes worth of driving until the noise comes.

Also, when pulling on the water pump pulley it slightly moves, as in that it's not rock solid in place....Reason why I say this is because I heard that one way to test your water pump to see if it is starting to go bad is to try and move the pulley that's connected to it...good pumps will not move at all.

Any suggestions? Thanks.