Losing water

[thegr81]

I hope I'm not repeating history but I'm losing about a gallon of water every couple days. Those of you that know me no I've blown up a couple of these but the car runs flawlessly no smoke coming out the exhaust but I think the cap on the reservoir definitely leaks everytime I turn off the car. I'm thinking of replacing the cap atanyway. I don't have a thermostat in but I've done that two other cars before and didn't have an issue. Anybody got any ideas? And the temperature gauge is reading fine and there's no destination or overheating unless the water level get low. That's how I first noticed it the reservoir was completely empty. Could the water be evaporating out the cap? What a bad radiator do that? I don't know