My honda civic is running hot but not all the time. I have changed the radiator, the thermostat and also flushed the engine. After driving the interstate for one hour it is fine and then when I get to the City the temp gauge will start to rise. The cooling fan is running. This does not happen all the time. I can drive in the City I live and it does not run hot. Only after a long drive and then stopping and restarting does it occur. It seems to have started after a new compressor was installed on a/c but it will run hot without a/c on. Could the water pump be causing this? Its about all left to change but may thinking is a water pump is either bad or good with no in betweens. Thanks, jm.

Water pumps are normally replaced on Hondas, when the timing belt is replaced. A bad water pump is about all that's left, if you bled the air from the system properly.