I have saildrives (Yam SD20s on 3GM30
One of them runs hot because I cant shut the Yanmar
gate valve from the leg and thus fill the saltwater strainers . Thus the engine
can never get enough water
to stop a degree of steam out of the engine exhaust
Guess what I am going to do next time boat is out of the water
Isolate the SD20 leg pickups and fit new marelon through hulls and gate valves!