first I'd solve why the coolant ain't being drawn back into the rad: bad recovery cap or leak in the hose or container (above coolant level being burped out) that is keeping vacuum from drawing the coolant back to the rad when the system cools off. IF (I ain't sure) recovery tanks are vented (very well might be as the hose comes in thru the bottom) then the hot coolant could simply be evaporating out of it as it sits.
New cap. I checked the tank and hose... no leaks. Indeed, the tank is vented. I closed off vent and applied air pressure with my mouth, finger over end of hose. It held air tight. I feel like I've covered all the bases, but no dice.
