tru dat son, now u be rollin in da civ fo sho'

 

I bought a 94 honda civic, when the car is in park it does not overheat at all but when i start driving the temperature gauge starts going all the way up within a few minutes, in order to go down i have to turn on the heater on max then the temperature gauge goes down again. I HAVE REPLACED THE WATER PUMP, THERMOSTAT AND TEMPERATURE SENSOR. The fan works ok. i don't understant why does the temperature gauge goes all the way up. When i open the hood i don't see any sign of overheating, it seens like it have right temperature, coolant is not boiling, i bleeded the coolant system. What else can i do? What seens to be the problem? Why do i have to turn on the heater in order for the temp gauge to go down?.....someone told me that the head gasket could have a leak, but no smoke comes out the muffler nor i see any leaks coming from headgasket......i have also put in one of those block seals liquid into the radiator with water, i followed the instructions......