Winterizing 3GMD

[sailstoo]

I have a raw water cooled Yanmar 3GM and want to assure that the anti-freeze gets circulated throughout the block. Even though I run it to warm it up before I introduce the anti-freeze, how do I know it's getting past the thermostat? How do I assure there's no water left?

[djmarchand]

I would add antifreeze (straight or 50/50 depending on what is in there now), start it up, put it in gear and run it 1000 rpm for 10 minutes. That will be enough to open the thermostat, circulate and mix the new stuff.

If you want to be absolutely, absolutely sure, I think there is an antifreeze drain cock on the back port side of the engine. Drain a sample and test, either in your freezer or with an antifreeze tester.

David

[Vasco]

Originally Posted by djmarchand

I would add antifreeze (straight or 50/50 depending on what is in there now), start it up, put it in gear and run it 1000 rpm for 10 minutes. That will be enough to open the thermostat, circulate and mix the new stuff.

If you want to be absolutely, absolutely sure, I think there is an antifreeze drain cock on the back port side of the engine. Drain a sample and test, either in your freezer or with an antifreeze tester.

David

Do you know how many gallons of anti freeze you'd go through running the engine for ten minutes? Well over ten gallons!! Just take the thermostat out, run the anti freeze through, less than one minute. Clean and test the thermostat while you've got it out. Replace. David, this is a raw water cooled engine.