Island Hopper

The 496 Merc. has a drain system that uses the air pump mounted on the front of the heat exchanger. This drains the seawater side of the system. Engine has antifreeze, and should be ok, but you may want to check it to be sure. There are also drain plugs in the waterpump 2 each, and one or 2 more. One I believe is in the oil cooler. Most are accessable on single engine set ups. Mine is twins, and not accessable, so I end up running antifreeze through it, then drain the plugs I can get to. Just before I am almost done with running the A/F through, I will shut it down, pull the fuel filter, replace about 1/4 of the fuel with 2 cycle oil. Then reinstall and run the remaining A/F through. This is an alternate way to fog the cylinders. Then change the oils and filters while it is still warm.

saubouin

Thanks again guys for your help. Island Hopper, I made sure to do the 2 stroke oil / fuel filter trick. Thanks guys! I can't wait for spring!

BryanTuvell

Most of these answers are correct but the manual says ensure the freshwater system is completely drained, unhook heat exchanger hoses etc. that's it.
Closed Cooling motor.
I ran Anti Freeze through the exhaust to help fight any corrosion. I then pumped the air valve and let some drain out.
VA? My location too, we have freezes but none long enough to sustain damage, it is always above freezing during the day.
My 2 Cents. I have the manuals, PM me if you need any data.
Bryan

Mustangous

Just curious, is there a better, more precise way? lol
How about dumping all of it and putting a certain mixture in it? if so what would that mixture be?

Island Hopper

The purpose is to get a light coating of oil on the pistons, and cylinder walls. In the old days we had fogging sprays to be used directly in the carburator intake. Fuel injected engines use this method. I do not recall a specific ratio, but if you have a fuel shut off valve, the ratios would be different. In my case I do not have shut off valves, and the mixture will be diluting while running, so I tend to use more oil. Enough to see a slight oil fog coming out of the exhaust. If you have shut off valves, the oil required should be some what less. I would guess half the amount, or 1/8 would be enough.