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Discussion Starter #1
I have a 1991Yanmar 2gm20f on a 1971 Pearson and am trying to winterize the raw water part. Seloc manual worthless for this. I think I can fill a bucket with freshwater to flush, and then antifreeze mix to stay in by turning engine with intake hose in the bucket. Is this all there is though? How do I know if it cleaned out the mixing elbow, or do I just go by ear? Anything else I should be doing for this (am doing the other winterizing things the manual says)?
Any help appreciated.
 

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You've pretty much got it. I've never flushed first, actually. I just fill a bucket with plenty of non-toxic antifreeze, put an intake hose in the bucket and let the pump pull it through the engine. I judge by the color or the exhaust. Don't stop the moment you see some pink or purple come out the exhaust--play it safe and let the engine keep pulling for a bit. You'll have some dilution of the anti-freeze, but the more the engine pulls in the better.
 

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On my 3GM30F I will run it for some time with fresh water from a hose keeping the bucket full. That flushes the system of an salt water and more importantly, warms the engine oil to make the oil change MUCH easier. Then shut down, fill the bucket with antifreeze, and restart and run until the stuff coming out is nice and pink.
 

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Jims got the right of it - run the engine a bit to warm it up, then close the seacock pop the hose and put it in a bucket of antifreeze.
Have someone standby to refill the bucket if needed, restart the engine and pull AF through the system.
Shut off the engine and drain the oil/change the filter.
Refill the oil.
Take a rag, wipe up the old oil spills then use that rag and stuff it in the air intake.
Stuff another rag in the exhaust.

Take your engine key and wire it to the seacock handle with a note that says 'rag in intake' as a reminder.
It's impossible to remember to open the seacock if you have to get the key off the handle.
 

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Discussion Starter #6
Thanks Chuckles and Jim, I actually ran it all summer in the Hudson river, mostly fresh water, so will pull through some water first maybe or just do the AF. Will plug the air intake and exhaust also. I had previously drained the SW intake hoses all the way into the engine and when I checked today there was ice there, so poured some hot water into the one going into the engine and was ready to try to start, but the yardmaster suggested I wait for the warmer weather coming this weekend (mid Hudson valley). I was a little concerned about icing in the mixing elbow or somewhere so took his advice.
 

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On my boat, I don't bother pulling the intake hose...way too much trouble. All I do is close the seacock, open up the strainer and pour water, then AF into the strainer. Just as I'm running out of AF, yell to my wife to cut the engine. Couldn't be easier.
 

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Just a quick thought on your statement of adding "antifreeze mix". I don't think you should use straight, undiluted, anti-freeze, not premixed to 50-50, etc. The reason is that it is going to mix to some extent within the block/muffler, etc. as it pushes the water out. After say 3 gallons being pushed through, you should be down to nearly straight anti-freeze, and that raises another possible concern. The freezing point of straight anti-freeze is higher than properly mixed anti-freeze. I don't rely on using pre-mixed due to the inability of controlling how much water is in the final mix, and don't want anything to freeze either. Solution I use is to run the 100 degree anti-freeze in motor, not the much weaker 50 degree stuff that i use in water system, bilge, etc.. Costs a bit more, but don't need a ton of it and the undiluted freeze point drops quite low. Note that I store the boat in Maine, so low temperatures are often lower than most need worry about.

One other thing I do is remove the engine raw water thermostat to insure that all of the passages get flushed. Even if you warm up the motor before flush, as soon as the cold flush passes the thermostat, the thermostat starts closing pretty fast, blocking off parts of the internal passages. Since you should leave the system full over the winter to reduce internal corrosion from air, I just leave the thermostat out until spring, with a note on the ignition key to replace it.
 

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mbsl, don't confuse polypropylene glycol with ethelene glycol. The first is for winterizing water systems and should not be diluted. The second is used in engine cooling systems and is diluted 50/50.

Also your discussion applies to raw water cooled engines, but not to fresh water cooled engines.
 

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mbsl, don't confuse polypropylene glycol with ethelene glycol. The first is for winterizing water systems and should not be diluted. The second is used in engine cooling systems and is diluted 50/50.

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Not if you buy pre-diluted AF. Just make sure you read the label before buying...concentrated vs. pre-diluted.
 
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