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Re: 1983 Yanmar 3GMD REPLACEMENT
If you can afford it, check if the later 3 cylinder 20HP Yanmar (3YM20) will fit on to the same mounts and line up with your shaft.
Expensive, but compared with the old GM series, these are beautiful motors. They are fresh water cooled so other than cleaning the heat exchanger occasionally, there should be no more corrosion worries. Cold starting is far better.
I had one in my last boat and going back to a 2 cylinder GM20 in my present boat really showed how crude the older engines are. At least they are reliable but the salt water cooling system does require diligent attention to anodes etc.
Otherwise, if on a budget, maybe find a GM that is not too flogged out and overhaul it.
Replacing with another brand is always a hassle, as nothing lines up, so the labor cost to do that would be better spent on the engine itself.
Last edited by arvicola-amphibius; 04-30-2015 at 06:34 PM.