This car has been having overheating problems since I got it about 3 weeks ago. We have changed the thermostat. Talked to the mechanic that the car was brought to and he says it's unsolved mystery with this car. He changed the water pump 3 times and has pressure checked the car leaks and tested for head damage. Everything is fine. Changed the thermostat numerous times. He has even aked advice from like 3 other mechanics and they can't figure it out. Well this is the problem. The car doenst run hot till after about an hour of running it constantly. The water I guess boils out of it when it runs hot and we put more water in it and runs fine for another hour. Or so. Checked the fans also. They come on when you turn the ac on. We have even tried to connect a toggle switch thinking maybe it don't come on sometimes. Dindn't fix the problem. Checked the purge line and it's fine. And the hoses aren't collapsing. Can anyone suggest anything or give any answers to what seems to be the problem. Also when he takes the radiator top hose off and puts it in a bucket no water comes out until it heats up which I guess the thermostat is opening up and just a little comes out. When he accelerates the car more comes out and then it just stops. Could the radiator be plugged or is it something else.