Had a growling/knocking noise int he engine compartment, also a slight vibration, especially at around 2000 RPM. Pulled the belt off and spun some pulleys, couldn't believe how rough and gritty feeling the water pump was, with slop in the shaft ta boot. All that without leaking, and no cooling system problems!! Replaced the water pump and oh what a difference in how quiet the Blazer sounds now, and it is vibration free. Just about like getting a new car.

 

Glad you got her fixed.