Mitsubishi Repair: 1998 Mitsubishi Mirage 1.5L Overheating, blown head gasket, mitsubishi mirage

Question
I have a 1998 Mitsubishi Mirage 1.5L and it's overheating. I've done all to it
that I've thought of with a couple exceptions. I replaced the water pump and
the thermostat and flushed the radiator and replaced the on/off switch thing
for the radiator fan. I checked the radiator fan and it works. What else is
there to do? It begins to overheat then it just drops back down to normal
temperature (right beneath midway on the gauge). I turn on the heater... and
It doesn't blow hot air into my car it seems to not work either. Could I have
blown a gasket and that causing it to overheat? I haven't replaced the
radiator cap... could that be a problem also? But would it be able to cause
this make to overheat?  

Answer
Mike: The way to tell if your car has a weak or blown head gasket is this way, does it blow white smoke out of the exhaust, have you seen drops of water in the oil when you check the oil in the engine, have you done a pressure check on the engine? How about something as easy as enough coolant in the water mix for the engine. Then yes I would replace that radiator cap. What about the radiator its self, how old is it? Could something had fallen down in behind the radiator so it is not getting air pushed through it as it needs to work? My repair manual also talks about incorrect ignition timing too. It could be that the heater core is bad in your car and so there is no way for the heat to even get inside the car. You should have that checked. You could have a vacuum leak as there is hoses that control the opening and closing of vents that move the heat into the car. Or you could have vent that is stuck closed inside the heater. You might have to just replace the radiator, as it is maybe not doing its job. They do get gummed up inside, there are shops that will flush the whole system and that might be something else you might try. Hope this helps and God bless: Linda