Jeff, Yup, it's the ERA I just got. The car has not been well maintained over the last few years and needs a lot of TLC, which it is getting! Sounds plausible the seal is letting air on the cool down. I recently installed a temporary overflow catchment (old 1 gallon
antifreeze jug). The water pushed out into the jug when hot is not fully returned to the engine when cold. Maybe, 40 to 60% is returned, resulting in a net loss.
For now I'm not adding watere to see if at some point it STOPS pushing water out and thats the new "level" it likes. Which would be LOWER than I had before!
Bigdog, air flow isn't your problem, must be circulation or something.