I just resently purchased a 1986 4 Winns with a 470 Mercruiser. It has a closed cooling system which I'm not familiar with. I live in Michigan so I have to winterize the engine. I can't seam to find a article that tells which plugs to remove to insure all sea water is out of the engine. If you could direct me to a article or put me in contact with someone to asked that would be great before the freeze comes.Also I just read one of the postings that says if the out drive is in a vertical position all the water will come out of it. Is that true!
Drain the sea water side of your heat exchanger , & the hose that connects to it from the transom.....If you have a power steering cooler then remove the hose from the transom at that spot instead. Make sure that your anti-freeze is the right concentration for how cold it really gets there....Look in the 'search' function under "winterizing" for more info......JK