My 02 chrysler is over heating, my mechanic put a new water pump and time belt in it and it is still over heating, now he thinks it needs a new head gasket, what do you think it could be, and if its the gasket how much will that cost me?

Replace your thermostat.. its a lot cheaper and i dont think you have a clogged radiator..just look at your radiator and your water lines to see if you even have a leak..and as for the mechanic a blown head gasket. easy way to check it.. look in side your radiator and see if it has a milky tan colored oil coming out if not your head gasket is still good.

I have the same problem my mechanic just replaced the radiator cap and the over heating is already gone. He said the cap spring can no longer contain the water even if its still at low temperature causing the disappearance of water inside the radiator which later on increases the temperature rapidly that causes the overheating.

If it is the head gasket there will be coolant in the oil or oil in the coolant, I would check to make sure the electric fan is operating, could also be a stuck thermostat or clogged radiator (both of which are MUCH cheaper to check and repair than a head gasket change.