My car recently started overheating a lot. Even when i went to a friends house about 3 blocks from my place it overheated. The radiator and thermostat where replaced about a year ago. so i don't know what it might be. if i fill it up with coolant, the next day it will be empty or close to empty, but i don't see coolant leaking anywhere. I don't really know much about cars! Please help! :]