Inboard engine winterization

BabaYaga said:
I find that a bit sweeping, must it not depend on the engine model? On mine (Beta 20 hp) the heat exchanger certainly is a low spot in the cooling circuit, made worse by the tilt towards the stern.
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Do you mean the calorifier which can be fitted low down. Normally engine heat exchangers are on the top of the engine and often include the pressure cap for adding coolant as shown here http://betamarine.co.uk/portfolio-item/beta-20/
 
theoldsalt said:
Do you mean the calorifier which can be fitted low down. Normally engine heat exchangers are on the top of the engine and often include the pressure cap for adding coolant as shown here http://betamarine.co.uk/portfolio-item/beta-20/
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No. Although the heat exchanger is at the top of the engine, for the water to drain completely as Tranona claims, the run must be down hill all the way. Otherwise some water will remain, in my case in small tubes of the heat exchanger. Expensive!
 
theoldsalt said:
I think the VP MD17 is a raw water cooled engine (not indirectly cooled) so should be flushed with 50/50 mix anyway if wintered ashore so the gearbox would be protected.
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Not so if it has been fitted with a conversion kit for fresh water cooling! However the raw water enters via the gearbox before it goes to the sea water pump and then on to the heat exchanger so my comment still applies!
 
BabaYaga said:
I find that a bit sweeping, must it not depend on the engine model? On mine (Beta 20 hp) the heat exchanger certainly is a low spot in the cooling circuit, made worse by the tilt towards the stern.
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Depends on where the antisyphon valve is fitted. If it is between the pump and the heat exchanger then there may be a small amount of water left in the HE. If it is between the HE and the injection point then the water will drain out through the pump when you remove the impeller as the HE is higher than the pump.
 
BabaYaga said:
No. Although the heat exchanger is at the top of the engine, for the water to drain completely as Tranona claims, the run must be down hill all the way. Otherwise some water will remain, in my case in small tubes of the heat exchanger. Expensive!
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I sometimes wonder if there's a misunderstanding about how freezing water causes damage. When water freezes it expands by a small amount compared to liquid water - 4% by volume from memory - so it is only water which is trapped in a space with absolutely no expansion space which will cause any damage. Any vessel which has been drained down, even if only a small amount of water has been removed, will not be damaged by freezing water provided there is the 4% expansion space.

One just needs to think about the design of a component and whether there is any totally "trapped" water to decide whether freezing might cause a problem. Clearly, water remaining in a low point in a system has plenty of expansion space.

Flushing through with antifreeze to prevent corrosion is a different matter, of course.

Richard
 
RichardS said:
I sometimes wonder if there's a misunderstanding about how freezing water causes damage. When water freezes it expands by a small amount compared to liquid water - 4% by volume from memory - so it is only water which is trapped in a space with absolutely no expansion space which will cause any damage. Any vessel which has been drained down, even if only a small amount of water has been removed, will not be damaged by freezing water provided there is the 4% expansion space.

One just needs to think about the design of a component and whether there is any totally "trapped" water to decide whether freezing might cause a problem. Clearly, water remaining in a low point in a system has plenty of expansion space.

Flushing through with antifreeze to prevent corrosion is a different matter, of course.

Richard
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An open ended metal pipe filled with water can certainly fracture from freezing – if the water towards the ends solidify before the water in the middle.
Not saying that it will happen every time, but it might sometimes. A heat exchanger matrix is expensive and difficult to repair. Some antifreeze in the cooling circuit before lift out is cheap insurance IMO, depending on the climate of course.
It is standard practice here, I guess for a good reason.
 
I wonder how screen washer systems cope. Mine freeze multiple times each winter There must be a soft element to absorb the expansion as well as open ends
 
Water at 4 deg C is at its densest, so sinks to the bottom, allowing the surface to freeze first... risk your own engine, but personally I wouldn't risk mine. not for a few quids worth of antifreeze...
 
In my indirect cooled OM636 its 50/50 in the freshwater side.
The saltwater side including the hydraulic gearbox cooling looks after itself and it has suffered minus twenty at least during one winter no problem
 
I know that my exhaust has places where water lies, water trap, muffler, gearbox cooling etc. Once ashore, I run the engine with a temporary fresh water supply to flush any salt out of the system, to cut down on corrosion, and just before stopping the engine, I introduce antifreeze into it, partly as a corrosion inhibitor, and partly to stop any of the trapped water freezing, and possibly causing damage. I consider the cost of 5 litres of antifreeze to be a well spent insurance premium.
 
Halo said:
How long is a piece of string? Suggest you mix up a 5 litre container 50/50. Use a watering can to put it into open strainer with engine on tick over and get someone to shout when it comes out blue or red from exhaust. Stop filling switch off and keep remainder for next year. Works ok for me.
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This is standard practice in the Baltic. It saves mucking about trying to drain the heat exchanger. The antifreeze contains an anti-rust ingredient which helps to protect the circuit. In our case with a Volvo strainer we just take the top of that and pour the mixture in until it comes out the exhaust as above. You don't have to dismantle anything.
You do need to drain down the domestic water though, particularly the hot water boiler. In many Swedish yards they simply put a compressed airline on the drain valve and blow the water out through the taps.
 
Gladys said:
It means that water on the surface freezes, and if it gets colder the water underneath then freezes and could then bust something..
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It is impossible for the pressure in the water to build up against the layer of ice such that the container will crack rather than the ice simply float up on top of the water. Unless the ice has nowhere to float up but that is a confined space which is not what we are talking about.

Richard
 
RichardS said:
It is impossible for the pressure in the water to build up against the layer of ice such that the container will crack rather than the ice simply float up on top of the water. Unless the ice has nowhere to float up but that is a confined space which is not what we are talking about.

Richard
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You want to tell that to the nineteen people whose calorifiers burst due to freezing, in our yard a few years ago.

The only inconvenience I've had was the bursting of a fresh water filter, which for the want of a drain plug, stupidly had no means of draining it.
 
Gladys said:
Water at 4 deg C is at its densest, so sinks to the bottom, allowing the surface to freeze first... risk your own engine, but personally I wouldn't risk mine. not for a few quids worth of antifreeze...
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Gladys said:
It means that water on the surface freezes, and if it gets colder the water underneath then freezes and could then bust something..
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That's fresh water that is at its most dense at 4C

Seawater continues to become more dense as it is cooled right down to its freezing point.

I don't see the relevance of either to the current topic though. But it means that in an engine block, for example, freezing will probably begin at the bottom, but since the ice formed is less dense than the seawater it will float to the top..

The most relevant fact is that Volvo Penta stipulate that when laid up for the winter the seawater system should be drained and then filled with a 50% antifreeze solution.

The OP only came here to ask how much antifreeze he will need! I think he had that information by about post #11.
 
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