Coolant change
The anti corrosive properties of ethyl glycol (anti freeze) have a usable life of five years. So anti freeze should be change every five years. I recently did mine and I am glad I did. I have a 1989 Hunter 30 I purchased last year and when I drained the anti freeze it was dark and thick. Remove the coolant over flow tank - empty and clean. Remember this anti freeze is poison and you will have to dispose of it properly. I brought along a couple of gallon jugs. One to put the used anti freeze in and one to mix the new anti freeze. The pet cocks on my 2gm20 were located on the starboard side of the engine. Take the "radiator" type cap off of the heat exhange tank. I used a soda bottle to collect the used anti freeze and transferred it to the empty gallon jug. The upper pet cock is for the fresh water drain for the heat exchange. Once you have drained the coolant from the heat exchanger and the block, add a 50/50 mix of water and anti freeze. I was advised that a stronger mixture will actually coat the heat exchanger and caused the engine to run hotter. I am in the automotive field and automotive engines also cool best with a 50/50 mix. Good luck - if you want to e mail me feel free to - brendagail@mindspring.com -Doug
