I wouldn't disconnect the overflow tank - that won't tell you anything. Practically every vehicle will expand coolant and port the excess to the overflow bottle. When the radiator cools, it will suck back coolant from the overflow tank. So what I'm saying is -- just about any car will lose coolant if the overflow tank is disconnected. When the coolant getsw hot, it will exit the radiator through the pressure cap, but won't be able to draw the coolant back into the radiator when the engine cools.

1977 CJ-7, fiberglass body, AMC 360 w/ headers, DUI ignition, Edelbrock intake and Holley 4150 carb, TF999, Dana 300, 4.56 gears lockers, York air comp, 4" susp lift, 2" body lift, BFG 35" M-T tires, Megashifter, AGR pump & box, REP8000 winch.