We replaced that hot water tank that I'm sure everyone was tired of reading about, in the process I lost coolant from the closed fresh water cooling system on the Yanmar 2GM. Although we have not had a chance to get out, I have made an effort to test the connections to the tank, engine heat exchanger, etc. I made sure that every hose clamp was tight, filled the expansion tank to almost the "full" level and filled the engine heat exchanger. I figured there would be air in the lines and would have to fill the hoses and heat exchanger in the hot water tank. I ran the diesel to warm-up, shut it off and let everything cool down. Once cool I pulled the cap off the engine heat exchanger and put about 2 cups of coolant in. I have since done this same thing two more times, adding about the same amount of coolant each time. I'm thinking now that is a lot of coolant. I checked the hoses at the engine and water tank, no leaks I can see. Checked the exhaust, not water vapor like a leaking head gasket. Am I being too concerned? Am I missing something? There is a green sheen down in the bilge sump which was where the coolant leaked to when I had the original issue. Not enough to pump out and the bottom of the sump is about 5-6' below deck level so too far to sponge out.