How much propylene glycol for winterising?

[Poey50]

I'm thinking ahead to winterising the Nanni 29hp engine. I can't find any figure for the volume of prop glycol to fill the raw water system. What might be a ballpark figure? I'd prefer a high estimate as there is always the winter after this and I'd prefer to have too much than too little.

 

[RichardS]

I'm thinking ahead to winterising the Nanni 29hp engine. I can't find any figure for the volume of prop glycol to fill the raw water system. What might be a ballpark figure? I'd prefer a high estimate as there is always the winter after this and I'd prefer to have too much than too little.

Are you intending to fill it with PG or use commercial antifreeze? Either way, 100% concentration will be less efffective than 50:50.

Richard

 

[davidaprice]

With my Volvo Penta 2002 (18hp) engine, I use a 10 litre bucket (50/50 water and glycol), and stop when there's clearly glycol in the water coming out of the exhaust. I always have a litre or two left over, which I flush through the heads. This is Helsinki, Finland, where -20C is not unusual and -35C is possible.

 

[VicS]

I'm thinking ahead to winterising the Nanni 29hp engine. I can't find any figure for the volume of prop glycol to fill the raw water system. What might be a ballpark figure? I'd prefer a high estimate as there is always the winter after this and I'd prefer to have too much than too little.

The obvious solution is to buy a ready diluted mixture that will give the level of protection you need/ desire.

However 10% by volume freezes at -3C,
19% at -8C,
29% at -14C,
40% at -22C,
50% at -34C
and 60% at -48C

 

[Poey50]

At the moment I've got 1 US gallon (3.8 litres) of Starbrite antifreeze which is pg based. It is freeze resistant to -11 degrees C and I was planning to use it undiluted as I imagine it will suffer a bit of dilution when drawn through. So maybe two more bottles of same.

 

[BabaYaga]

I'm thinking ahead to winterising the Nanni 29hp engine. I can't find any figure for the volume of prop glycol to fill the raw water system. What might be a ballpark figure? I'd prefer a high estimate as there is always the winter after this and I'd prefer to have too much than too little.

For my 20hp Beta I use 2 litres of PG diluted to 50 percent, so 4 litres in total. This is plenty.
As I see it, protecting the heat exchanger and anti siphon is the important thing. Though I have a Volvo type water trap, which will not be damaged by freezing water.

 

[Tranona]

I'm thinking ahead to winterising the Nanni 29hp engine. I can't find any figure for the volume of prop glycol to fill the raw water system. What might be a ballpark figure? I'd prefer a high estimate as there is always the winter after this and I'd prefer to have too much than too little.

You must live in a very cold climate if you are concerned about freezing of the raw water system. Better to just run it dry and drain it. However, the chances of it freezing in most parts of the UK are just about zero.

 

[Poey50]

You must live in a very cold climate if you are concerned about freezing of the raw water system. Better to just run it dry and drain it. However, the chances of it freezing in most parts of the UK are just about zero.

Just to be clear the boat will be out of the water over winter. I'm also assuming I'd get better corrosion inhibition by filling with antifreeze rather than just draining.

 

[Tranona]

Just to be clear the boat will be out of the water over winter. I'm also assuming I'd get better corrosion inhibition by filling with antifreeze rather than just draining.

Corrosion is not a big issue with the raw water side of freshwater cooled engines as it does not get anywhere near the engine waterways which is what causes corrosion in raw water cooled engines. Clean the heat exchanger out from time to time if you do get a build up of crud.

 

[thinwater]

Just to be clear the boat will be out of the water over winter. I'm also assuming I'd get better corrosion inhibition by filling with antifreeze rather than just draining.

Actually, that is a poor bet unless the glycol is rated for engines.

Also, the glycol is less than 25% it can ferment, turning very acid. I always cringe when I hear folks skimping.

 

[VicS]

Just to be clear the boat will be out of the water over winter. I'm also assuming I'd get better corrosion inhibition by filling with antifreeze rather than just draining.

Fill the engine freshwater cooling circuit with your normal antifreeze. That will give you the best frost and corrosion protection.

Flush the seawater circuit with freshwater to remove all the salt. Then either drain thoroughly, paying particular attention to anywhere where water may be trapped eg filter. pump, gearbox cooler, exhaust riser and water traps, or fill with an antifreeze solution ( PG if you prefer).
You mention Starbrite PG antifreeze but you don't say if its an engine coolant or one for protecting freshwater systems. They market a wide range of products.

 

[JumbleDuck]

You must live in a very cold climate if you are concerned about freezing of the raw water system. Better to just run it dry and drain it. .

That's assuming he can can drain it. I have just stuck 2L of ethylene glycol antifreeze (it's nowhere near as bad for the environment as doom-mongers say), diluted 50:50, through my 1GM10 because it is physically impossible for me to drain the water trap wihout dismantling the exhaust system.

 

[Poey50]

You mention Starbrite PG antifreeze but you don't say if its an engine coolant or one for protecting freshwater systems. They market a wide range of products.

It's pink and has instructions for use in both engines and freshwater systems.

 

[STOL71]

I'm thinking ahead to winterising the Nanni 29hp engine. I can't find any figure for the volume of prop glycol to fill the raw water system. What might be a ballpark figure? I'd prefer a high estimate as there is always the winter after this and I'd prefer to have too much than too little.

Make sure you use ethylene glycol for a Nanni diesel - the blue stuff.

 

[RichardS]

Make sure you use ethylene glycol for a Nanni diesel - the blue stuff.

I'm not sure which type of antifreeze is best for Nanni engines .... I always use long life OAT stuff whatever the engine ... but I don't believe that the colour is ever going to be a conclusive indicator of which type it is.

Richard

 

[JumbleDuck]

I'm not sure which type of antifreeze is best for Nanni engines .... I always use long life OAT stuff whatever the engine ... but I don't believe that the colour is ever going to be a conclusive indicator of which type it is.

I think blue = no OAT, red = OAT. I have just bought some red stuff for my car and it is ethylene glycol + OAT.

 

[VicS]

Make sure you use ethylene glycol for a Nanni diesel - the blue stuff.

I'm not sure which type of antifreeze is best for Nanni engines .... I always use long life OAT stuff whatever the engine ... but I don't believe that the colour is ever going to be a conclusive indicator of which type it is.

Richard

I think blue = no OAT, red = OAT. I have just bought some red stuff for my car and it is ethylene glycol + OAT.

All readily available antifreeze in the UK is, AFAIK, ethylene glycol based. You have to go out of your way to find propylene glycol based antifreeze.

The colours are not standardised ( VP antifreezes are green and yellow for example)

Read the label. If you need an OAT type buy one that says it's OAT If you require a non OAT type buy one that says its "inorganic acid" technology or low silicate or suitable for older engines.


As far as motor vehicle are concerned my understanding is that you should be using an OAT type with aluminium radiators but a conventional non OAT type with copper and brass radiators.

 

[NormanS]

I'm thinking ahead to winterising the Nanni 29hp engine. I can't find any figure for the volume of prop glycol to fill the raw water system. What might be a ballpark figure? I'd prefer a high estimate as there is always the winter after this and I'd prefer to have too much than too little.

Surely it's not necessary to fill the whole of the seawater side. It's worth running an antifreeze solution through, just before stopping the engine for the last time. That way, any water remaining in silencers, water traps, or undrainable parts will be protected from freezing.

When you drain the coolant from the freshwater side, use that. It will still be good enough for the purpose. (Assuming you have used antifreeze).

 

[Poey50]

I'm the OP and I'm happy to see the thread closed (while recognising they have lives of their own!) This is what I've decided ...

... I am going to be using propylene glycol, rather than ethylene glycol. It was not hard to get, not very expensive and seems a better choice if I decide to drink it,

... it is going in the raw water system not the indirect cooling system (I'll be flushing that too but replacing with ethylene glycol),

... I'm not totally convinced that it is worthwhile to fill the raw water system but I've got the stuff now and will try it, but next year I may just flush it with fresh water and drain it as thoroughly as I can.

Thanks to all for contributions.

 

[thinwater]

I'm the OP and I'm happy to see the thread closed (while recognising they have lives of their own!) This is what I've decided ...

... I am going to be using propylene glycol, rather than ethylene glycol. It was not hard to get, not very expensive and seems better for the environment,

... it is going in the raw water system not the indirect cooling system (I'll be flushing that too but replacing with ethylene glycol),

... I'm not totally convinced that it is worthwhile to fill the raw water system but I've got the stuff now and will try it, but next year I may just flush it with fresh water and drain it as thoroughly as I can.

Thanks to all for contributions.

I've got to refute this urban legend:

There is NO DIFFERENCE between EG and PG in the marine environment, and I challenge anyone to find scholarly work that says otherwise.

EG is more toxic to mammals. On the other hand, zinc is lethal to marine organisms but often taken by people in material doses as a dietary supplement. Doctors prescribe it for certain things. Thus, correlating marine toxicity with mammal toxicity is false without support. If you read the MSDS information on both you will find they are equal.

The US Wildlife Department lists EG as harmless in waterways (not withstanding the COD impact, of course). Soaps, even biodegradable types, are much worse.

Biodgradeability is equal. Many studies on the internet, US and international. EG actually has slightly less impact (degrades a little faster, and less is used because it is a more effective freeze depressant).

So this is pure urban legend. What is important is to avoid drinking EG. If the calorifier circulates engine coolant, watch it for leaks, or at least don't drink the hot water.

(30 years in the industry, chaired a trade group that made both)