Non-toxic antifreeze in closed loop engine/waterheater.

[rwidman]

Originally Posted by Sandero

Just curious... what would happen if he ran the engine with the seacock open and let all the water in the cooling get pumped out until there was only engine exhaust fumes coming out? Would all the water / coolant in the cooling system be pumped dry? For a few minutes it would seem that the engine would not over heat.

Or does water always manage to remain in the system which can freeze and split something?

Water would remain. And you could damage the engine.

If you want to drain the engine, get the manual for the engine to find out how to do it. There will be some drains on the engine and/or you may have to remove some hoses. You may have to remove the hoses to the water heater heat exchanger and blow the water out. Usually, this would only be done on a raw water cooled engine.

The best bet is to use the antifreeze recommended by the engine manufacturer and not try to second guess them.