Re: Is it hard to convert inboard engine to antifreeze?
It's a little more involved than that, The heat exchangers as they are known are make of copper with a tube bundle and both a raw water side and an antifreeze side. The thermostat housings are also different.
What type engine are you wanting to convert to a closed cooling system?
You do realize, after an engine has over a 125 hours or basically 1 years use, converting to a closed cooling system is not recommended.