OK still learning the I/O thing i have been learning alot from this forum. i have posted previous on winterizing my 1983 470 merc i think i now the answer but i want to hear from the experts i have been following the advise on winterizing your alpha 1 and the motor. they talk about closed cooling system and open cooling system now i think i got a closed because at the top near back of motor there is a tank full of antifreeze is this a closed system and i only need to drain heat exchanger or do i need to drain more?
One last question i have read it's better to convert to a 4 inch heat exchanger, when i bought the boat i looked at motor the exchanger looks fairly new. is there some markings to determine what size i got or can i measure the out side diameter
One last question i have read it's better to convert to a 4 inch heat exchanger, when i bought the boat i looked at motor the exchanger looks fairly new. is there some markings to determine what size i got or can i measure the out side diameter
(aft plug is seawater), just a couple of additional things. Make sure that your antifreeze is up to spec, about 50% will protect to -34F. You can get a cheap tester for less than 10 bucks. If you have a power steering cooler, make sure that it drains when you drain the exchanger. After you drain the exchanger, pull the water hose off, if nothing comes out that means it drained through the exchanger and you never have to worry about it again (I have not drained my ps cooler in 17 years). With the 3" exchnger, you have to make sure that you have a reasonably accurate temperature gauge, and keep an eye on it. Try to change out your impeller at least every other year. Good luck and have fun with the old 470. BTW the appropriate pages for winterization are here (thanks to Eric):