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Old 23-10-2019, 08:53   #1
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Winterizing Yanmar 2GM20, drain plugs

So, winter is approaching here in Germany and the new to me 2GM20 in the new old boat needs to be winterized. It is a raw water cooled model. If I understand the manual correctly - a big if - the recommended method is, to undo drainplugs on the engine itself and let the water out of the water jacket. Beyond that, I have not found any information in the manual on this topic, especially no information on where the drain screws are ...



Now, there is one big screw in the engine housing with a label saying "Zinc". Is this the one to open, is it the only one or are there more? If there are more, where are they located on the engine?


As is often the case with boat engines, accessibility is not ideal, although I have reasonably good access from 3 sides, so, I can't complain. Only the side with starter and alternator has poor accessibility.



Help appreciated ...
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Old 23-10-2019, 09:43   #2
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Re: Winterizing Yanmar 2GM20, drain plugs

I can not help you with the details of that engine's drains but...

I would start the process by disconnecting the raw water inlet from the seacock and from a bucket, feed 20 liters of a 50/50 mixture of propylene glycol/water though the engine before draining it. If you do this with the engine cold, it's probably best if you remove the thermostat first.

That way if you miss a spot it will not freeze and create a disaster.
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Old 23-10-2019, 09:47   #3
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Re: Winterizing Yanmar 2GM20, drain plugs

If you want to depend on the opinions of people you don't know and cant verify, have at it. Conversely, you can buy the engine service manual which will help you with both this and lots of other issues regarding your engine. Your choice!




Since there is no water jacket on a raw water cooled engine, it's pretty simple to winterize
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Old 23-10-2019, 09:49   #4
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Winterizing Yanmar 2GM20, drain plugs

I too would go the antifreeze route, just because there are other components too, like the water lock muffler and did you completely drain the motor.
Now Iíve never winterized a boat, so I canít speak from experience. But if you can leave a light bulb in the engine room say a 60 W one, that will keep things above freezing too, but of course the bulb could burn out.
An old fashioned light bulb of course, not an LED
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Old 23-10-2019, 09:51   #5
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Re: Winterizing Yanmar 2GM20, drain plugs

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Originally Posted by S/V Illusion View Post
Since there is no water jacket on a raw water cooled engine, it's pretty simple to winterize

What does that mean?
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Old 23-10-2019, 18:56   #6
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Re: Winterizing Yanmar 2GM20, drain plugs

If you look in CFs' library you will find the workshop manual which should tell you all you need. I always advise people to get one if you want to be able to help yourself & lets face it you aren't always where help is readily available if you are a cruiser.
Older Yanmar manuals have lots of good advice in them. They are a bit overzealous in their replacement schedule ( THINK $$$ for Yanmar ) IMO but well worth having.
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Old 23-10-2019, 19:01   #7
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Re: Winterizing Yanmar 2GM20, drain plugs

Sorry I was assuming you only had the operators manual but maybe you already have the service manual. I 'll ask Wotname to chime in maybe he knows as he had a 2GM20
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Old 23-10-2019, 19:02   #8
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Re: Winterizing Yanmar 2GM20, drain plugs

When I had a raw water cooled engine I used to remove the thermostat, start the engine and run 50/50 anti freeze through the engine. I don't know anyone in the Great White North that just drains the engine.
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Old 23-10-2019, 19:22   #9
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Re: Winterizing Yanmar 2GM20, drain plugs

There is a 2GM20 service manual in the CF library section (uploaded by me ).

There are two zinc anodes on the 2GM20. One on the exhaust side of the engine and the other in the head on the aft end of the engine. Both require a 24mm spanner and if they haven't been removed for a while, you will need a long extension to provide enough leverage to budge them - they will be tight.

The engine drain plug is on the exhaust side of the engine near the oil dipstick. If it isn't exercised and cleaned regularly, it all be clogged up with anode debris, salt deposits and rust. Rather than open the little valve on it, removed it completely and clean the crud out (of the block and the drain plug).

IMO, removed both anodes and the plug and have a good look inside looking of excess salt deposits (mainly calcium salts). The engine should be flushed regularly (say every couple of years) with salt removing product. I just use vinegar if the deposits are mild or hydrochloric acid if they are severe. Others prefer proprietary products. You will have to remove the anodes and thermostat before flushing.

Depending of the minimum air temperatures you expect to experience, you may need to use anti freeze product - but I can't speak to that other that say to check with what others do in your location.

I guess if the sea freezes in your area, you need something for sure
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Old 23-10-2019, 19:29   #10
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Re: Winterizing Yanmar 2GM20, drain plugs

Quote:
Originally Posted by S/V Illusion View Post
If you want to depend on the opinions of people you don't know and cant verify, have at it. Conversely, you can buy the engine service manual which will help you with both this and lots of other issues regarding your engine. Your choice!




Since there is no water jacket on a raw water cooled engine, it's pretty simple to winterize
This is great example of opinions (correct or otherwise).

Of course there is a water jacket on a raw water cooled engine The clue is in the description - raw water cooled!

Now an air cooled engine doesn't have a water jacket
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Old 23-10-2019, 20:57   #11
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Re: Winterizing Yanmar 2GM20, drain plugs

Have been winterizing my 3GM raw water cooled motor for 34 years in New York (thinking similar winters as in Germany). Have manual and does say to drain.
Never have drained motor to winterize, I would much rather leave antifreeze in motor than drain and allow motor to potentially rust away from inside.
Agree flush motor every few years, I use Rydlyme.

Thinking maybe when referring to no water jacket on raw water cooled engine poster meant... no heat exchanger?
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Old 24-10-2019, 12:13   #12
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Re: Winterizing Yanmar 2GM20, drain plugs

Since it is raw water cooled, it does have a water jacket. So, either drain that or use Potable antifreeze (Suck it thru the pump intake line). Regular antifreeze can create other problems.
If you just drain it, which will most likely be fine where you are, remember to loosen the plate on the back of the pump, to drain that housing, and also to drain the muffler. Pull the zinc plugs as you'll need to inspect/ replace them anyway.
Thermostat will have a by-pass so it'll either drain and/or be protected by the antifreeze.
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Old 24-10-2019, 13:24   #13
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Thumbs up Re: Winterizing Yanmar 2GM20, drain plugs

Quote:
Originally Posted by a64pilot View Post
I too would go the antifreeze route, just because there are other components too, like the water lock muffler and did you completely drain the motor.
Now Iíve never winterized a boat, so I canít speak from experience. But if you can leave a light bulb in the engine room say a 60 W one, that will keep things above freezing too, but of course the bulb could burn out.
An old fashioned light bulb of course, not an LED
The light bulb is often quoted but inefficient,
Heat around the engine compartment is most efficiently produced by using a tubular heater of 40 Watt available in 1ft,2ft, 3 ft lengths from $20 to $50

Search ebay for "panel heater greenhouse"

https://www.ebay.com/sch/i.html?_fro...house&_sacat=0
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Old 24-10-2019, 13:37   #14
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Thumbs up Re: Winterizing Yanmar 2GM20, drain plugs

Quote:
Originally Posted by a64pilot View Post
I too would go the antifreeze route, just because there are other components too, like the water lock muffler and did you completely drain the motor.
Now Iíve never winterized a boat, so I canít speak from experience. But if you can leave a light bulb in the engine room say a 60 W one, that will keep things above freezing too, but of course the bulb could burn out.
An old fashioned light bulb of course, not an LED
The light bulb is often quoted but inefficient,
Heat around the engine compartment is most efficiently produced by using a tubular heater of 40 Watt available in 1ft,2ft, 3 ft lengths from $20 to $50

Search ebay for "panel heater greenhouse"

https://www.ebay.com/sch/i.html?_fro...house&_sacat=0
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Old 25-10-2019, 09:03   #15
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Re: Winterizing Yanmar 2GM20, drain plugs

I owned a yanmar 2gmf. Also a Volvo 2002 and a couple of atomic 4s. Winterizing is similar on all of them.

I live in Kingston, Canada (Lake Ontario), where the water gets hard for the winter. And we get many freeze/thaw cycles.

First, do an an oil change.

Disconnect the seawater intake from the seacock and use it to suck up a few gallons of antifreeze. In the old days we used automotive antifreeze (like for a car radiator) but now we use plumbing antifreeze. I learned to run antifreeze through until the discharge over the stern looked the same as what was going in. For a 2gm that would be about 2 gallons. But antifreeze is SOOO much cheaper than a new engine (or engine repair) so I would run 4 gallons through. Shut down the engine, and you are done. Put away the key. This method means the water strainer, engine, muffler, water pump, everything is full of antifreeze. Thats what you want. Exposure to air is when you get corrosion (rust) or rubber parts dry out and become brittle.

Then find all the other components on your boat that have water in them and do the same with more antifreeze...the head, bilge pump, fresh water system, and even splash some into the bilge just in case.

Fill the diesel tank to the very top to limit water condensation. Charge the batteries and disconnect them. Open all the lockers below to help ventilation and reduce the chance of mold.

I've done this more times than I care to remember, with never any freezing damage.

Good luck to you.
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