100 degrees will not damage the engine , 115-120 will though. If you didnt replace thermostate when you did the water pump then that is one of the first things.Make sure to fill the upper radiator hose with water to before reconnecting. Make sure to warm the car up until you can watch by the needle on your temp gauge drop when the thermostate opens and then run the heater for a few minutes. You can also run your hand (with car off) down the front of the radiator and feel for cool spots. That would be clogged radiator. If it is half cold half warm then it could be thermostate or radiator (flow problem). Thermostate is cheap enough for the first thing.