Even their carburetors were strange with a little balloon for a fuel pump. The one thing I recall is that the little motors ran well when they ran, but when they stopped, it was easier to take them to the scrap yard than it was to repair them. I had the opportunity to work on a number of these motors in the late 1990’s when I was laid off and needed some income to stay afloat (pun not intended). I actually am guilty of having an 'ESKA Toss' many years ago at a Lake Catherine wet meet because it was the only motor that would not anger one of our members when we threw one into the lake (not to worry, we had a rope on each motor and did not leave them in the lake). This forum is probably not the best source for information on the ESKA outboard because nobody that I know collects the Tecumseh powered air-cooled motors from ESKA. The last company that I dealt with that had manuals and parts for the ESKA outboard was Certified Parts Corporation in Janesville, Wisconsin.
Rated at 5hp, it is an air-cooled motor however, if it is similar to some I have worked on in the past, there is still a water pump impeller in the lower end that pushes water to the bottom of the powerhead to condense gases and to keep heat from building up under the top cowlings. I am not an expert on your outboard, but I am fairly certain that it is an ESKA outboard manufactured in 1974 for Sears in Canada.