Originally Posted by WearyTraveler

There has to be a leak somewhere.

Check all of your hoses and your radiator. Check the hose to the coolant overflow for cracks. Could only leak under pressure.

Should really do a pressure check for the cooling system. Most radiators are pressurized between 10-14 psi or something like that. So you need a pressure tester. Some parts stores let you loan/borrow specialized tools.

http://www.autozone.com/autozone/ino...tingAndCooling

How to do a pressure test. http://www.autozone.com/autozone/rep...&subtitle=test