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Discussion Starter #1
Is it important to have the engine cooling water passages filled with antifreeze over the winter? Or is it OK to have the cooling system partially drained?
I have a 1981, 13 hp Volvo diesel. It is raw water cooled. I’m concerned that a partially drained system will promote internal corrosion. And I ask because if I use the raw water pump to winterize the engine and then remove the raw water pump impeller, much of the antifreeze drains out. I could first remove the thermostat and the impeller and use a pump to pump the antifreeze through the engine but that is more work and could possibly end up forcing water back into the exhaust.
Thanks, harbin2
 

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Ok to drain

Here is what I do:

  1. Drain the water from the muffler
  2. Run motor and put the anti-freeze through raw water pump until you see good flow of it in the exhaust stream
  3. Shut off engine and drain muffler
  4. Crack open impeller pump and drain the anti-freeze
DrB
 

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You can partially drain the antifreeze if you like, but I would use -100 deg, which can be partially dilluted and still protect. Some nooks and crannies might not fully displace the water. However, I would just leave it fully charged with anti-freeze.

I leave my impeller in all winter. It's good motivation to change it each spring.
 

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I agree with Minnewaska. That way you have antifreeze through the engine and muffler all winter. There are anti corrosion elements in the antifreeze which protect internal parts which would otherwise start corroding when exposed to air. Keep the impeller in and change impellers in the spring if desired.

Tod
 

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You are wasting your time. Drain it completely.
I fully drain fresh water lines by blowing them out. Some minute water does remain, but if more than I thought, it will cost me $20 in hose. Make that mistake with your engine and you could be buying a new one after cracking the block. For me, antifreeze let's me sleep.
 

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Anti freeze does have anti corrosion additives and will help the engine over an extended time.
A few years back, a couple buddies of mine decided not to winterize their engines and instead, put a small heater in the boat to keep the engines from freezing.
When spring came and they fired up their engines for the first time, the exhaust water was so thick with rust and corrosion, it looked like mud coming out of the exhaust port.
After seeing that, I promised myself that I would ALWAYS use antifreeze when winterizing and never just drain the water or use an engine room heater.
 

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Use the drain plugs and drain the barrel and exhaust manifold completely. I would not trust the anti-freeze trick, as I can never be sure it's getting into the jacket(s). It will go through the exhaust OK, but it will only get into the jacket(s) if the thermostat is open, and it probably won't be.
Take the gearbox coolant line off and blow the remaining water out of the gearbox and the water pump.

I very nearly lost my MD17C about 5 years ago when it froze solid. All the core plugs blew out and saved nearly all. I have a wee crack in the aft barrel, and it weeps very slowly, perhaps one drip every 30 seconds when warm. I live with it.

Be careful.

Rockter.

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Use the drain plugs and drain the barrel and exhaust manifold completely. I would not trust the anti-freeze trick, as I can never be sure it's getting into the jacket(s). It will go through the exhaust OK, but it will only get into the jacket(s) if the thermostat is open, and it probably won't be.
Take the gearbox coolant line off and blow the remaining water out of the gearbox and the water pump.


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So take out the T-stat first and then you don't have to worry if it is opened or closed.
 

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Is it important to have the engine cooling water passages filled with antifreeze over the winter?
Follow the instructions in your manual. My Vetus manual states as follows:

"To avoid corrosion the internal cooling system must be completely filled during lay up...[pour a litre anti-freeze in the filter and]let the engine run untill [sic] the anti-freeze has disappeared into the cooling system..."

Thus, Vetus recommends changing the coolant in the engine and filling the raw water portion of the heat exchanger with coolant, rather than leaving it empty after a flush.
 

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Discussion Starter #11
Basically, I’m trying to balance my time winterizing with making the engine last.
Since I’m retired, I’m more concerned about latter.

My practice has been to use the least expensive RV antifreeze. It's usually about $4 per gallon and says it's good for -50 and contains a corrosion inhibitor. To that I add some Prestone “Cooling System/Antifreeze Treatment” that claims it protects against cooling system corrosion. West Marine has products that range from 5 to 26 per gallon. It’s not real clear, to me, how much any of them do for corrosion protection. But, again, my main concern is whether to keep the system full or partially drained.

I DO like to flush the system with fresh water in the fall and to do this, I must remove the thermostat and impeller. I then use an external pump for the flush. When I see what comes out, I’m convinced that this is worth doing.

So, my plan will be to keep the system full. But I’m still not sure how to get it into the exhaust system without chancing getting it back into the exhaust portion of the exhaust manifold. I don’t believe my muffler has a drain.
 

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I bought the expensive ($25/gallon), environmentally-safe, antifreeze from West for the engine coolant change and raw water intake flush.

WalMart sells $4 a gallon, pink, RV potable water antifreeze to winterize your water tank. You simply flush it out with fresh water to de-winterize. I pumped a gallon through the water system to prevent the pipes from freezing and emptied another gallon into the marine head holding tank (after pumping out).

Is what you are referring to? Are you sure that is safe to put into the engine raw water intake?
 

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There is a difference between winterization anti freeze and coolant antifreeze. The later can be very expensive and not appropriate for winterizing the raw water intake.

The -50 deg (pink stuff) is usually between $4 and $6 per gallon. You have to be fairly sure that it is not mixed with water, or it will quickly lose its protective ability. The -50 rating is the temp at which it will protect against expansive bursting, it will freeze at a much higher temp and that temp goes up quickly when diluted.

-100 deg (blue) can be mixed with equal parts water and essentially becomes -50, IIRC. It usually sells for $10 to $12 per gallon. It is best for applications where it may mix internally with the water it is displacing. This is most common in engines, where the raw water may flow over top of dips that hold onto water. Once you stop pumping the antifreeze, the residual water mixes with the AF and dilutes that portion anyway.

By the way, some brands are pure, some are recycled aircraft deicer, if you care. That can account for the price difference.
 

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Discussion Starter #15
Hmmmm. As usual, these threads get you thinking and make you smarter. What I have been using is the Walmart stuff. At $4 per gallon, I'm almost certain it is the same stuff that WM sells for $5. Last year it was labeled as a Dow product. What I used a few weeks ago is labeled as a "Super Tech" product. These and the WM 5 dollar stuff all say they are good for -50 and contain corrosion inhibitors. I suspect it's all the same stuff from the same plant. I have used the same stuff in the engine and the water system.

I know that my procedure does not result in zero dilution. I have never had any damage but I do plan to use a lower temperature antifreeze in the future - for that reason. Our winters typically don't go below zero but I'd rather be safe (given the dilution).

BTW, another thing I typically do to limit the dilution is to blow and then vacuum everything I can out of everything I winterize using my wet vac.
 

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The West Marine Pure Oceans Engine Antifreeze & Coolant (green color) is propylene gylcol, with a recommendation to mix with water from 50/50 to 66/34.

The (WalMart) SuperTech RV & Marine Antifreeze is also propylene gycol, already mixed with water, but also has ethyl alchohol, Di Potassium Phosphate, colorant, and fragrance. It includes a warning:

Caution: not intended for use in engines as antifreeze/coolant, marine engines, closed boiler systems or solar collections.
 

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What's wrong with using coolant in the raw water intake (other than the expense)?
Will need some chemical guru to give you a better answer, but engine coolants typically say on the bottle not to use them at full strength. I don't know why. I think they are close to pure product. At the least, they are a waste of money with no added benefit I'm aware of.

Worst case, some are not environmentally friendly like the winterization fluids.
 

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Chuck....

You said....

So take out the T-stat first and then you don't have to worry if it is opened or closed

....unquote.

That is an idea there Chuck, but can you be sure it's mixing enough with the jacket water? The Volvo raw water cooling operates by the thermostat opening and the flow periodically skimming the hot water off the top of the barrels and cylinder head. There is no formal throughput through the barrels.

Even with thermostat out, will it mix enough?

I have a cracked aft barrel as witness to me getting it wrong (for other reasons than anti-freeze).

I nearly lost the whole motor. All the core plugs had blown and that saved a total loss.

Pls be careful.

Rockter.
 

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Another point, the wee fluid entry ports for the "skimming" are quite small, little more than the diameter of a pencil. They are prone to scaling, and they can virtually bridge off. The net result is that the motor slowly overheats. On shut-down you can hear the water in there boiling.

It's dead easy to fix. Take off the exhaust manifoild and use a broad blade screwdriver to remove the scaling. It has a heavily-staining, black, almost bituminous appearance to it.

Exhaust gaskets are expensive, however.

AND!!!!... make sure you do not put them on in poor light. I did, and got one of them the wrong way round. Net result, seawater comes out of the air filter on shut-down.

One of the darkest moments I have ever had.

And it took us some time to figure out what had been done wrong.

A last point, if anyone ever has a leaking gearbox seal on that motor, and the new seal leaks too, send me a PM. I have a learing curve 3 weeks long before we could fix it, and it was SO simple to do, in the end.


Rockter.
 
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