Coolant flows from the radiator to the water pump via the lower hose, then from the engine to the radiator via the upper hose.
As for your cooling issue, it could either be that your thermostat is stuck open, or that your new sending unit isn't reading right, or that the heater hose where it's mounted isn't getting the flow of the hot coolant. One other thing that came to mind when you installed the new sender was did you run a ground wire to it?
As for your cooling issue, it could either be that your thermostat is stuck open, or that your new sending unit isn't reading right, or that the heater hose where it's mounted isn't getting the flow of the hot coolant. One other thing that came to mind when you installed the new sender was did you run a ground wire to it?