Hi I have a 2001 Ford Explorer that is over heating. I don't know what is causing it. I just replaced the radiator, water pump and the thermostat. It was fine for a few months then my girlfriend was driving it to McDonald's one night, which is only 1 mile from we're we live, and it started to overheat. When she pulled over and opened the hood the reservoir cap blew off. She said the engine was hot but not where it was smoking or anything. She said it wasn't even bubbling out the radiator cap or anything. When we got it home and it sat over night we tried driving it again and it did it again. We let it sit a few days and then tried it again, this time it didn't do it.

Long story but I'm on house arrest so can't really check it out but I don't really know much about cars, so if anyone could please give me some advice it would be great. Thanks for any help.