Antifreeze

thinwater · Sep 16, 2013

More details needed.

This is a glycol-cooled engine with a heat exchanger? If so, for optimum corrosion protection you should run a 50/50 (-34F freeze protection) mixture in ANY climate. The corrosion inhibitors are formulated for that mix (I create formulations--chemical engineer). Clearly, it should be an engine formulated type, preferably for diesels.

Is 7F enough? No, as it will go well below that temperature. The problem is that each time it freezes it will be a partial freeze, where the ice floats and the glycol sinks. After a few cycles the upper portion of the engine will have only water.

I don't know how well the engine drains, but it is a gamble. Why not just refill it correctly? The useful life of the extended life antifreezes is 5-10 years.

Don S/V ILLusion · Sep 16, 2013

Two comments

Just opening the drains will not ensure all liquid drains.

Antifreeze begins to freeze at temp above that which your hydrometer indicates it is good at. If it is old or, although unlikely, separated into phases, damage can result.

Worth the chance?

nolasafari · Sep 16, 2013

Thinwater, thanks for the explanation helped me.
If in doubt and you have power wrap the engine with heat strip.

thinwater · Sep 16, 2013

And then there is the matter of how the FP was measured. Most hydrometers are +/- 10F on a good day. A refractometer is much better. And you need to know whether it is EG or PG (it takes considerably more PG).

Read this link on AF and boats.

http://www.practical-sailor.com/blog/-11059-1.html

Claude L.-Auger · Sep 16, 2013

Being also in a cold climate i understand your predicament now that the boat is on the hard. 7 degrees is definitely not enough. Here's what I would do. I would drain as much out as possible, and refill with a mix around -40 so that when the new antifreeze is mixed with what left of the old one it will probably result in the recommended -34. Your problem is to run this through the engine so that it does go everywhere.

I have done it this way in the past: Remove the thermostat and reinstall the housing. You will need a new gasket. Disconnect water intake hose from the through-hull and put it a a 5-gallon bucket. Run a fresh water hose through the 5-Gallon bucket to keep it filled. You will need someone to help. Start the engine and run it a minute or two. The antifreeze will run though the engine without having to wait for it to reach operating temp because thermostat is removed. Shut engine and re-install thermostat. Shut and remove freshwater hose from bucket. You might be lucky and be able to re-use the gasket, but I would have another one just in case.

Once thermostat re-installed, after having emptied water off the bucket, re-fill it with antifreeze mix, then re-start engine and run the few seconds it takes for the mix to come out of the exhaust outlet. You entire engine, heat exchanger and exhaust system will now be winterized ! This operation is best done with 3 people. One to hold hold the bucket filled with antifreeze mix, one to start and shut the engine when ready to do the job, and one to hold a bucket under the exhaust outlet to avoid antifreeze being dumped on the ground. Good luck

Claude L.-Auger · Sep 17, 2013

SunCat said:
The problem is that I am 1400 miles away from my boat, but I have a friend in the area that could open the drains and in doing so removing the pressure from the possible ice build up inside the engine, since now there is an scape for the possible ice. The problem is only with the antifreeze side of the cooling, no the raw water cooling that goes thru the exhaust, the raw water side was properly winterized.

If your friend could at least remove the thermostat (only 2 bolts) after draining and refill with proper antifreeze mix you would stand a better chance. Then drain some and measure low temp resistance. The idea is to try to have as little low temp mix in the system as possible to avoid damage caused by expansion.