I have a Westerbeke 4-107 with fresh water cooling. For some time now it has been loosing antifreeze coolant, just a few ounces after running several hours.

I have searched diligently for an external leak and am convinced none exists. That means it must be through the exhaust manifold or heat exchanger; oil cooler is salt water cooled.

Am I missing something? Taking the heat exchanger off, way back on the engine, a real chore! Any ideas on how to detect?

Thanks, Eddie