I have a 1998 civic lx and it is overheating. I changed the thermostat, timing belt and water pump and still having the same problem. When it starts to get close to hot, I turn the heat on full blast and the temperature automatically goes to normal. It does not get hot in idle or park, only at driving speeds. I was thinking about flushing the radiator or getting a new radiator. The fan is hooked up to automatically come on when ignition is turned on. The fan is blowing the correct way. I could really use some help from someone knowledgeable in the area. Thank you

Did you follow the correct procedure for purging the air from the cooling system?

What would be the proper procedure?

Replace the radiator and refill it with a 50/50 mixture of the proper antifreeze and distilled water. Precisely follow the draining and refilling procedures in your Owner's Manual to purge the system of air. Failure to do this can cause the engine to seriously overheat, resulting in a warped aluminum head and a blown head gasket. I suspect passages in your radiator are partially blocked by phosphate scale (mineral build-up), due to using tap water.