Dead simple engine winterizing

I have always been amused at the different systems and gimmicks that boaters post about on the subject of engine winterization. Everything from devices that attach to the top of your strainer to plumbing systems that attach to the raw water pickup piping/hoses.

None of that is necessary or even makes engine winterizing easier.

Almost every marine engine whether propulsion or genset has a raw water strainer on the intake system. If you don't have one, you probably need to install one. To winterize, simply close the seacock that feeds the strainer, open the top on the strainer, start the engine and then pour antifreeze into the top of the strainer until a strong pink color comes out of the exhaust.

Preferably do this on the hard, so after you shut the engine down, you can put the top back on the strainer and open the seacock. This lets the water that is trapped inside the ball run out. If you don't do that you can ruin your seacock when the water inside the ball freezes.

Now some of you will say- won't the engine starve for coolant and overheat or won't running the engine dry harm it. No and no. At idle the engine produces very little heat and the few gallons of antifreeze going through will cool it fine. Running dry for a few seconds won't harm the engine either, particularly with antifreeze lubricating the impeller.

If you try this and your engine won't suck up the antifreeze, then you need a new impeller. I tried this procedure on my genset and couldn't get it to suck up antifreeze. So I pulled the cover off of the raw water pump and found half the vanes missing. Replaced the impeller and it sucked that antifreeze right up.

So, if installing aids to let you antifreeze your engine makes you happy, well fine. It won't make it any easier.

David

I had a knowledgeable person recommend hooking a low pressure air line to the water intake and blow all the liquid out of the engine to store it for the winter.

David that method works on an engines positive displacement pump. For a/c centrifugal circulating pumps you need the funnel to raise the head of the anti-freeze to feed the pump.
Drain hot water heaters, disconnect suction and discharge hoses on potable water pump and operate to blow any water out of pump housing. I gravity dump my FW system and place electric heaters with freeze settings. We leave the boat in the water thru Winter and the water temperature rarely gets near freezing so compartments below the water line are near water temperatures.

ktdtx said:

I had a knowledgeable person recommend hooking a low pressure air line to the water intake and blow all the liquid out of the engine to store it for the winter.

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I prefer the antifreeze method as it takes care of low spots at can't clear and if water or condensation does form and drain to low spots, there is antifreeze there already. If air pockets can form in many engines after changing coolant, I would be worried pockets of water could remain just by blowing out a system.

For some systems I'd you know what you are doing, blowing them out first eliminates a lot of required antifreeze...but I still like to use it in case of low spots or condensation.

My easy method is: take hose off strainer, attach to hose going to bucket of anti-freeze, start engine (or ac pump), let a certain amount flow through - done.

I do the same thing for the water system. Bypass and drain HW heater. Drain water tanks. Attach hose at water tank to bucket of anti-freeze. Open one faucet at a time till strong pink is flowing. - done.

I use a small hand pump to empty and then clean out strainers.

Ken

Go south for the winter. Problem solved!!

kchace said:

My easy method is: take hose off strainer, attach to hose going to bucket of anti-freeze, start engine (or ac pump), let a certain amount flow through - done.

I do the same thing for the water system. Bypass and drain HW heater. Drain water tanks. Attach hose at water tank to bucket of anti-freeze. Open one faucet at a time till strong pink is flowing. - done.

I use a small hand pump to empty and then clean out strainers.

Ken

Click to expand...

I also follow this method

ktdtx said:

I had a knowledgeable person recommend hooking a low pressure air line to the water intake and blow all the liquid out of the engine to store it for the winter.

Click to expand...

Don't recommend this. I did this with the jet boat behind the house. Water was left behind in a few pockets and froze. Kissed that engine goodbye.

In SWFL, I get to SUMMERIZE!

High Wire said:

In SWFL, I get to SUMMERIZE!

Click to expand...

Lucky me. I get to do that too.
Yes for that it's safe to blow out the engine. (Though I don't know why you would)

Greetings,
Only 10 posts? Much too early to summarize. Got to have at least 75 posts. 15 on topic, 30 describing what is wrong with the other 29 suggestions, 20 suggesting the best and worst materials and 10 smug comments regarding the benefits of living somewhere warm.

RT Firefly said:

Greetings,
Only 10 posts? Much too early to summarize. Got to have at least 75 posts. 15 on topic, 30 describing what is wrong with the other 29 suggestions, 20 suggesting the best and worst materials and 10 smug comments regarding the benefits of living somewhere warm.

Click to expand...

It is also too early to post a brief statement describing the main points of this thread.
Perhaps in an hour or two....

ktdtx said:

I had a knowledgeable person recommend hooking a low pressure air line to the water intake and blow all the liquid out of the engine to store it for the winter.

Click to expand...

psneeld said:

I prefer the antifreeze method as it takes care of low spots at can't clear and if water or condensation does form and drain to low spots, there is antifreeze there already. If air pockets can form in many engines after changing coolant, I would be worried pockets of water could remain just by blowing out a system.

Click to expand...

mbevins said:

Don't recommend this. I did this with the jet boat behind the house. Water was left behind in a few pockets and froze. Kissed that engine goodbye.

Click to expand...

Yeah, I use air pressure to clear our freshwater systems, but wouldn't do that with engines or genset...

-Chris

There is another method. Put the boat in heated storage for the winter. Of course, our local yards that keep boats in heated storage do winterize all systems just in case.

On a cold engine will not most of the antifreeze go out the exhaust because the thermostat is closed?

I use method in post #5 for engine and generator.
I did add a brass tee to sea cock side of AC strainer with brass hose cap. I install a 3/4 x 3/8" hose into bucket to suck up 50/50 fluid. I disconnect the potable water pump at suction hose from tank and use the same hose to do the potable water system. I have the bypass hose and valves on the hot water heater. I vacuum out all strainers and bilge of any water. I pour a couple gallons of 50/50 in the bilge and actuate the bilge pump switches.
Once complete I'm Ready for winter and any projects I have been putting off during the summer season.

kchace said:

My easy method is: take hose off strainer, attach to hose going to bucket of anti-freeze, start engine (or ac pump), let a certain amount flow through - done.

Click to expand...

Same here. 5 gallon bucket, an extra length of hose, and a few gallons of pink stuff through the engines. I also keep bilge heaters on and the water never freezes, so probably overkill, but better safe than sorry.

I winterize a ton of boats and am the guy liable for them not freezing up.

1- Many boats can suck a strainer dry faster than you can physically pour the bottle, even at idle. Seeing as the strainer outlet is at the top this method is problematic on many boats.

2- Many boats do not have any space to physically pour the PG into the strainer.

3- Unless you are physically testing what comes out of the stern, and comparing it to the bottle with a refractometer, you have not properly winterized the engine you have merely guessed at it. If you don't have a refractometer just suck in more. Heck even for small sailboat engines Westerbeke recommends a five gallon bucket of AF. My own Westerbeke 44B takes 5.5 gallons to match bottle strength.

4- Pulling the hose off the strainer inlet and attaching a winterizing hose fed to a 5 gallon bucket is more consistent, with no spills, and allows you to physically capture samples at the stern while still sucking it into the engine. I've yet to come across an intake hose I could not remove in a few minutes plus I get to examine the hose clamps while I am at it. If you graduate your 5 gallon bucket with a Sharpie marker, at one gallon increments, you will know exactly how much has been sucked in when you sample the exhaust.

5- Samples out the stern should match the bottle strength as measured by a refractometer. If the virgin bottle sample reads 8F then what comes out the stern should also read 8F. Diluting PG antifreeze, which has already been diluted at the factory, leads to freeze ups which get very costly. Rarely does a spring go by where I don't have a call for a frozen and split heat exchanger etc.. PG is cheap, suck more in if you plan to guess at it.

6- I have numerous power vessels that take over 10 gallons per engine to match bottle strength. Each vessel gets a winterizing spec sheet for gallons per engine, FW system, AC system, generator, raw water wash down, etc.. I also record fitting sizes so I bring the correct adapters and hoses. This way there is no wasted AF the following years, and no guesswork. The winterizing method which involves simply "seeing pink" is a dangerous slope. I can't tell you how many times I have heard "But I saw pink." after I have just diagnosed a frozen & split HX...

This owner "saw pink" he also wrote a big fat check for a new HX come spring. This is what was in the system..



PG is cheap engine components are not.. Winterize carefully..

I just winterized our 41' President with 225 Lehmans. When we saw the blue coming out the exhaust we had put 5 gallons of -100 in. Testing it then with the refractometer, it tested only to 0. It took another 5 gallons to get to -30. We used the Sea Flush adapter that goes into the strainer, very easy to use. No way I could have kept up pouring the AF into the strainer manually. For the A/Cs and the generator, I could not fit the Sea Flush due to the location of the strainers. I got some adapters that screwed into the strainers and hooked up a garden hose to a bucket. In all I ended up using 48 gallons of -100 AF to do the 2 engines, generator, A/Cs, water system, heads, seawater washdown, bilge pumps and drains. It took a lot more that I expected, but by testing each outlet until we got at least -20 that was what it took. Still cheaper than frozen and cracked stuff.

Capt Kangeroo said:

On a cold engine will not most of the antifreeze go out the exhaust because the thermostat is closed?

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We only winterize the raw water circuit. No thermostat involved.

The coolant circuit is already 50/50 antifreeze/water and ok for the winter.
(That's the mix we use in the CT area, good for approx -34F. Other areas may use a different mix).

jskinner30PII said:

I use method in post #5 for engine and generator.
I did add a brass tee to sea cock side of AC strainer with brass hose cap. I install a 3/4 x 3/8" hose into bucket to suck up 50/50 fluid. I disconnect the potable water pump at suction hose from tank and use the same hose to do the potable water system. I have the bypass hose and valves on the hot water heater. I vacuum out all strainers and bilge of any water. I pour a couple gallons of 50/50 in the bilge and actuate the bilge pump switches.
Once complete I'm Ready for winter and any projects I have been putting off during the summer season.

Click to expand...

If by 50/50 fluid you mean regular antifreeze supplied as 50/50 mix I would suggest that you are using the wrong stuff for winterizing. Regular antifreeze is ethylene glycol and is quite toxic. I would NEVER put it in the boat's potable water system unless you plan to flush the system with a couple of hundred gallons of water before use. Also running regular antifreeze through your heat exchanger and exhaust is dangerous to small animals (dogs, etc.) unless you capture ALL the fluid that comes out the exhaust.

You should be using propylene glycol non-toxic antifreeze for both the engine and the water system. It come is two varieties - pink good to about -50 and blue good to about -100 (at full strength).

clynn said:

Same here. 5 gallon bucket, an extra length of hose, and a few gallons of pink stuff through the engines. I also keep bilge heaters on and the water never freezes, so probably overkill, but better safe than sorry.

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Can you address bilge heaters? What do you use? My concern was burning the boat to the waterline. Thanks!

Mike

I have used the Caframo electric heater in my bilge (Defender or WM) to keep it from freezing when it gets down into the teens at night. The Caframo is reasonable quality, ie better than Walmart Chinese stuff, and has a low temp, low fan setting. It would easily keep the engine room above freezing at these low settings. It is low profile and won't easily tip over.


But even though it is well designed to prevent accidents, well accidents happen. A better solution is a Wolverine oil pan heater. These are a flat pad, roughly 4x5" for a 250 watt unit that glues to the engine oil pan. It's primary purpose is to prewarm the engine for starting, but it will also keep the engine room warm, well- above freezing at least.


Because it is glued to the oil pan and has the mass of the engine to distribute its output, it is very, very unlikely to cause a fire.


David

[

A better solution is a Wolverine oil pan heater. These are a flat pad, roughly 4x5" for a 250 watt unit that glues to the engine oil pan. It's primary purpose is to prewarm the engine for starting, but it will also keep the engine room warm, well- above freezing at least.

Because it is glued to the oil pan and has the mass of the engine to distribute its output, it is very, very unlikely to cause a fire.

David[/QUOTE]

Does it draw the same as my traditional block heater?

Greetings,
Mr. mb. "Does it draw the same as my traditional block heater?" If your block heater is 250 watts then yes. A watt is a watt is a watt for all practical purposes...

The size, expected temperature, and air turnover of and engineroom will determine how many watts you need to keep it above freezing.

I tried a 300 watt magnetic heaters on each of my 3208s in Annapolis during the winter...never even could tell they were on.

RT Firefly said:

Greetings,
Mr. mb. "Does it draw the same as my traditional block heater?" If your block heater is 250 watts then yes. A watt is a watt is a watt for all practical purposes...

Click to expand...

Yes RT you're right. But a traditionally mounted block heater draws about 10amps making it a1000 watts . That can get expensive running 24/7 all winter. Just sayin ?

Well, this would be my first winter inside water so I have a question.

I have integrated two valves before the strainer input so I can choose to use the water from seacock or internal connection on which I can attach the hose and put it in the bucket/barrel/bilge or whatever. I did that with bucket over last winter, but on the ground and no problem with it (except that bucket is empty relatively fast). After shutting it down, I have opened the seacock to drain the water from it.

So if I stay in the water, I will not be able to empty the seacock. Only thing that I can do is remove the hose from it and dry the water with towel as much as possible and then pour antifreeze inside (with seacock closed all the time). Is this also needed?

Is that good enough if the boat draft is 0.74 meters (2.42 feet) and water surface (river) freezes once per year for about 20 days (not every year, but average). That would be if ambient temperatures fall a bit below or at about -10C (14F). Boat hull is made of fiberglass (with polyurethane core).

Are there more things that should be done with seacock in case of leaving the boat in water?

Some people here say that they leave one or two 100W incadesant light bulbs inside engine room and that it is enough. But I cannot rely on hearsay. Again, this is much safer then leaving any electrical heating device.

What are your experiences in this case?

If by 50/50 fluid you mean regular antifreeze supplied as 50/50 mix I would suggest that you are using the wrong stuff for winterizing. Regular antifreeze is ethylene glycol and is quite toxic. I would NEVER put it in the boat's potable water system unless you plan to flush the system with a couple of hundred gallons of water before use. Also running regular antifreeze through your heat exchanger and exhaust is dangerous to small animals (dogs, etc.) unless you capture ALL the fluid that comes out the exhaust.

You should be using propylene glycol non-toxic antifreeze for both the engine and the water system. It come is two varieties - pink good to about -50 and blue good to about -100 (at full strength).


TDUNN
I use 50 below, the pink stuff. Not a 50/50 mix.

Nidza:


For the first time, I am going to leave my boat in the water in similar conditions to yours, maybe a bit worse, over the winter. I am going to flush antifreeze, but as you note you can not open the seacock to drain the water, when you are in the water.


What you have to be most concerned about is the little pocket of sea water inside the seacock ball. This will freeze in extreme conditions and burst the ball. There are two solutions:


Most large seacocks have a drain fitting on the side that will let you drain the contents of the ball when it is closed. Just open the fitting, let it drain to the bilge and close it back.


But small seacocks that feed the head, air conditioner, etc don't have these. In this case I plan to remove the hose that connects to them downstream or connect a temporary hose and blow through the seacock (yes by mouth) to force the water out of the open seacock. Then while still blowing, close the seacock. If a little water is left in the ball, that is ok, but it won't be full so it won't burst the ball when it freezes.


David