Rodney wrote:
I may be misunderstanding you here. There is no difficulty telling
visually whether a yanmar is raw cooled or fresh. the heat exchanger
in the fresh-water-cooled engines is a rectangular tank above and to
the right of the cylinder head with a radiator cap in it. It has four
hoses, in and out for both raw and fresh water.

A raw cooled engine does not have this at all.

Yes, it's raw. I always leave the door open to be enlightened when I know I
am not an expert.