[C320-list] Help with Perkins M-30

[Dave Hupe]

 Rick-
To lose that much coolant in 45 minutes and not see it in the boat (under the engine?) would make me suspicious that you are blowing the coolant out the exhaust while motoring. The engine coolant level in the heat exchanger tank would drop significantly by losing 45-50 ounces. 
Are your clamps around the front and rear boots on the heat exchanger tube tight so that there is no leakage between the seawater cooling system and the engine antifreeze system?  Another possibility is that the heat exchanger tube itself is leaking (allowing engine coolant to migrate into the small heat exchanger tubes and then out the exhaust).
I don't mention these ideas from experience, but replaced my heat exchanger tank and have a  good experience with the system. 
Dave Hupe
1994 C320 (#32)