I'm trying to do a coolant change on my 1999 (I think, SN OL258272) Mercruiser.I've had the boat since it was new and I missed the part in the maintenance schedule about changing it every two years, so I want to do a good job. My Service manual, which covers 1996 and 1997 models says there are drain valves on the side of the block. So far I've been in there by feel, and with a mirror and flashlight and I can't find them. My engine is almost totally below the deck, so it's a bear to work on. My fall back has been to disconnect the cooling hose between the heat exchanger and the water pump. I get a couple of gallons out this way. I then refill the system, run it until the engine is up to temp and do it again. After five cycles, the coolant is still green. I know if I keep this up, I'll eventually get the antifreeze out, but that is only half of my problem. My tap water is loaded with calcium and other minerals. I don't want any of it remaining in my cooling system. If I repeat the flushing process with distilled water, it will take 50 gallons and I won't really know when I'm done. Is there any way to totally drain this system? Could I blow it out with air? Does the dealer have a magic machine that would make it worth my time and money to have this done?
See item numbers 4, 5, 6. 