De Tension the accessory belt, grab the water pump pulley, and see if you can wobble it. Spin it also and see if there is any resistance. I would also scan the car and monitor the coolant temperature to see if it agrees with the gauge.
98 Riviera SC3800 All stock except gutted air box.
1970 Buick GS455 Stage1, TSP built 470BBB, 602HP/589TQ
Best MPH, 116.06 MPH, Best ET, 11.54