Before i changed my coolent, the car ran perfect. Now after using that Prestone Radiator Cleaner, my car overheats.

According to the directions, im suppose to leave this solution in my system and run the car for a period of 2 days or have it running for 3 hrs. During those 2 days, it overheated a few times, then i decided to flush out the system completely and refilled with 50/50 coolent. After a few days, things seemed to be fine, but just now, it overheated. Does this sound like what Hoonta is going through?

Is my water pump going bad? If coolent circulates from viewing down in the radiator cap, then the pump/thermostat SHOULD be fine.

Just list the items that is associated with overheating: Bad water pump, thermostat....what else?