How much anti freeze to put in engine coolant system

[The Boat Studio]

New to boating. Wondering how much anti freeze I should put into my 1800 BMC diesal engine over winter. We have the type of cooling system whereby the hot engine water is cooked by a tank in contact with the hull and the canal water (not sure the name for this sorry) we have no clue about quantities to use or even which product to use! Any help greatly appreciated! X

*cooled not cooked obviously!

*cooled not cooked obviously!

[Alan de Enfield]

Firstly check - is there antifreeze already in the system ?

 

You can get a little 'tester' from Halfords (etc) for about £5, this will show you the level of protection that is already in the system.

Look at the 'colour', basically there are two types of antifreeze 'red' and 'blue' ( or slight variations) these do not mix so use the same type as is already in the system.

 

You are looking for about a 50% water / 50% antifreeze mix.

[Paul C]

I'd say between 25% and 50% concentration of antifreeze.

 

Which stuff? Well, I'd say there's a 99.9% chance that you have the normal "blue" antifreeze which is ethelyne glycol, or none at all. Its possible, although very unlikely, that someone's used longlife stuff, propylene glycol, which last 5 years instead of 2 and is typically pink in colour. There's also more modern, more environmentally friendly coolant additives used in modern cars but just mentioning for completeness. Don't be fooled if the coolant is orange in colour - its probably rust.

 

The type of cooling is "keel cooled" and the thing that does it, is called a "skin tank".

 

 

The actual quantity to add will depend on:

 

1) the concentration of the coolant already in the system

2) the coolant capacity of the system

3) how much can be added now, to top it up (for example if its full of water, you'd need to take some out, to fit the coolant in).

 

1) is measurable, 2) is probably a guess unfortunately.

 

There's something to be said for draining the entire system if its unknown/water/rust coloured, flushing it out thoroughly, then filling it with pre-mixed coolant and at the same time taking a note of how much went in, for future reference.

 

Or you could just assume its a bit low in level and concentration, and add some undiluted until its full.

Edited November 18, 2015 by Paul C

[Chewbacka]

Sounds like a new boat to you :-)

 

I aim for about 45%. Pure antifreeze is not a good as water for carrying heat away from the engine, so you do not want too much - say over 50%. The antifreeze - more normally called coolant - also contains corrosion inhibitors which for the blue stuff last a couple of years or so. So if you don't know the history of the boat it may be wise to think about changing the coolant over the next few months. Do NOT dump the old stuff into the canal or onto the towpath as it is toxic. Take it to your local council recycling centre.

 

As above do not mix red and blue coolant as it can cause a powder to form that can cause big problems.

Whilst red has a longer life than blue, it is not suitable for many older engines.

 

Enjoy your boating

[cuthound]

Are you looking for someone to tell you the total capacity of your cooling system? If so all I can tell you is that it varies between different boats.

 

My boat has a Beta 43 engine in an Alexander shell, and has an engine coolant capacity of 40 litres. The heating system on my boatbhasca capacity of around 25 litres.

 

When I changed my engine coolant, I used Ford Superplus Premium antifreeze, because it lasts for up to 10 years, and changing the coolant on my boat is a right pain:)

 

https://www.fordpartsuk.com/shop/ford_super-plus_premium_anti-freeze_coolant_5ltr_f_1336808.htm

 

It is cheaper from eBay.

 

I used a 50% solution in the engine and a 25% solution for the central heating.

 

As others have said, if your existing antifreeze is blue and you want to change to red (or vice versa) then the system mustbbe thoroughly fliushed first.

 

Edits to correct poor grammar.

Edited November 18, 2015 by cuthound

[The Boat Studio]

Thanks everyone. Yes the boat is new to us. We took a sample of water and there was a very very slight blue tinge, hardly there at all really. Will get the checker from halfords and see what it says. Pretty sure we will need to add more. I have no idea of the coolant capacity - this seems to our the main problem, as don't know how much 45% or 50% would be?! We could flush it all out and start again, but I'm afraid I wouldn't have a clue how to do that either! Sorry - complete learner here!

[Paul C]

If you aren't sure how to flush it and replace, then I'd recommend a boat yard or friendly marine engineer do it - its not a basic job. Well, it can be once you know how, but you need to properly do it to get it all out (or most); and you need to ensure the system is properly bled too. There's a lot of variety with boats because it depends on the type and location of the calorifier, the pipework, the skin tank(s) etc etc and all boats are a bit different to each other. Also its possible to heat radiators in the cabin using engine coolant - effectively heating for nothing. If you have this, then the amount of coolant total in the system, and the space you need for expansion, is much more. And bleeding will also include bleeding the radiators.

[The Boat Studio]

If you aren't sure how to flush it and replace, then I'd recommend a boat yard or friendly marine engineer do it - its not a basic job. Well, it can be once you know how, but you need to properly do it to get it all out (or most); and you need to ensure the system is properly bled too. There's a lot of variety with boats because it depends on the type and location of the calorifier, the pipework, the skin tank(s) etc etc and all boats are a bit different to each other. Also its possible to heat radiators in the cabin using engine coolant - effectively heating for nothing. If you have this, then the amount of coolant total in the system, and the space you need for expansion, is much more. And bleeding will also include bleeding the radiators.

Thanks for this. Do you think that flushing the system is the best thing to do when unsure of coolant capacity? Or is it okay to just add a bit of anti freeze in and hope for the best!? We have no cabin radiators so don't have to worry about that..

[Paul C]

1. test its strength

2. look at the level

 

These 2 things determine how much, and what concentration to add. If you don't know the overall capacity then once you've added some (and know what concentration you added) if you accurately re-test the strength and do a bit of maths, you can work out (approximately) the overall capacity.

[ditchcrawler]

Thanks for this. Do you think that flushing the system is the best thing to do when unsure of coolant capacity? Or is it okay to just add a bit of anti freeze in and hope for the best!? We have no cabin radiators so don't have to worry about that..

Check what the strength is first, it may be OK This is the Halford one http://www.halfords.com/motoring/engine-oils-fluids/antifreeze/halfords-antifreeze-tester-meg

[The Boat Studio]

Yeah that makes sense - thanks all. Will go to Halfords tomorrow!

[bizzard]

Dip a finger into it and dab a touch on your tongue. Hardly any sweetness too weak, very sweet too strong, medium sweet okay. Spit back in to save wasting. .

[Loafer]

If it were me, I'd drain it all out anyway, on a 'new' boat. I'd also put in a couple of stopcocks and 'T' pieces, so that it is easy to replace the coolant in the future. You can only do that when it's drained.

 

It's then only half an hour's job to replace every 2 years. Even if the coolant bit is still doing its job, I've heard that some of the anti-corrosion additives need replacing.

 

Not sure how true that is, but it helps me sleep easy.

[Guest]

If it were me, I'd drain it all out anyway, on a 'new' boat. I'd also put in a couple of stopcocks and 'T' pieces, so that it is easy to replace the coolant in the future. You can only do that when it's drained.

 

It's then only half an hour's job to replace every 2 years. Even if the coolant bit is still doing its job, I've heard that some of the anti-corrosion additives need replacing.

 

Not sure how true that is, but it helps me sleep easy.

It is well documented in various places, and I tend to believe it. The blue stuff appears to be shorter lived.

[cuthound]

 

It's then only half an hour's job to replace every 2 years. Even if the coolant bit is still doing its job, I've heard that some of the anti-corrosion additives need replacing.

The blue antifreeze contains glycol. Glycol keeps its antifreeze properties indefinitely, how much depends on the concentration, but as you say the corrosion inhibitors fail over time.

 

The Halfrauds antifreeze tester only tests concentration, not anti corrosion properties.

 

To test this, put some steel washers in a bit of your old antifreeze and see if they rust.

[Loafer]

The blue antifreeze contains glycol. Glycol keeps its antifreeze properties indefinitely, how much depends on the concentration, but as you say the corrosion inhibitors fail over time.

 

The Halfrauds antifreeze tester only tests concentration, not anti corrosion properties.

 

To test this, put some steel washers in a bit of your old antifreeze and see if they rust.

 

I don't think they would, but they might corrode if you put different metals in there, mightn't they? I thought it was dissimilar metals in water that caused this problem...

[Paul C]

 

I don't think they would, but they might corrode if you put different metals in there, mightn't they? I thought it was dissimilar metals in water that caused this problem...

 

Its an oxygen concentration gradient isn't it?

[Loafer]

 

Its an oxygen concentration gradient isn't it?

 

I'm not sure, but I imagine there's SOME oxygen around within the coolant. I'm just too scared of stuff like that, I change the coolant every two years. I'm happy being 'sad' but it works for me!

[Sea Dog]

It might be useful just to round up some of the good advice you've already been given, because you're on your way for an anti freeze tester which is good, but you may be considering leaving the old coolant in there which may not be.

 

If, as you say, you have a blue tinge to your coolant it should be changed every 2 years in order to preserve it's anti corrosion properties. It seems safe to assume that you don't know that it's been changed this year or last, so you'd be wise to do so if that's the case.

 

If you're changing coolant that may be long overdue, you'd be wise to flush the system. If you're gonna flush the system, you may as well change to 5 year (commonly red) coolant.... if your engine is compatible.

 

You can buy coolant concentrated or pre diluted. Mix concentrated with water at 5 litres to 5 litres for 50%, 5 litres to 10 of water for 33%, or 15 of water for 25%. Some (like me) prefer deionised water because it doesn't have any corrosive impurities, others use tap water.

 

If you're unsure about mixing with water, pre diluted will be at 50% with deionised water. Frankly, if you buy somewhere like eurocarparts, where it's 9 quid for 5 litres of pre-diluted red and about 17 quid for concentrate, there's not much to be saved by buying concentrate and mixing it with deionised water, which can be surprisingly expensive all of a sudden.

 

The concentration depends on both minimum expected temperatures and your engine manufacturer's recommendations for anti corrosion requirements. Check your manual (there may be one online) or ask someone with the same engine. 25% to 50% is commonly recommended, I use 33%.

 

To drain your system you'll need plenty of plastic bottles. I save old 5 litre screen wash ones for this. Once you've drained into these bottles, you'll know your system capacity. The skin tank is usually a variable large unknown, which is why no-one can tell you what your capacity is. My own system is about 35 litres. This needs to be disposed of safely at your local recycling centre as anti freeze is poisonous.

 

To empty your skin tank you can either remove the bottom hose,drain into the bilge and clean it all out again, which I wouldn't recommend, or buy a cheap syphon pump and such out through the top hose connection after you've drained the engine.

 

The trick with refilling is to remove trapped air. If you have an engine heated hot water tank (calorifier) this makes air locks more likely, but is usually where the highest point of the system is and where the air can be bled from.

 

Now, that hasn't explained exactly how to do the job since systems vary, but you should now have all the key points. If you get someone to do it for you, you'll probably be able to watch and learn so you can do it next time. If you're gonna read your manual or a guide, you may be better equipped to know what they're on about!

 

Most of that you already know from earlier posts and you'll find more ideas and info using the search function, but I hope that pulling it together for you helps. Good luck!

[ditchcrawler]

Just seen this http://www.lidl.co.uk/en/our-offers-2491.htm?action=showDetail&id=28632

[Chewbacka]

I suggest that with winter coming on the first priorty is to check the concentration to avoid freezing damage and adjust if too low.

 

You need to have coolant with corrosion inhibitors that still work, so whilst it is a good idea to change it as you can not easily check it, I don't think it is urgent and within the next couple of months should make little difference.

[Sea Dog]

Then he'll be changing it in January You're right, of course, Chewy, another couple of months will make little difference as long as the antifreeze concentration is right.

[The Boat Studio]

Woah! So thank you very much for all your replies guys..I still feel slightly unsure about what is best to do. Ideally flushing the system would be great but not very realistic for us right now. Will need to wait until we can get her to a boat yard. For now I think we will test the water, add more in if needed, test again. If we need to add a fair bit then we will have new anti - corrosive stuff right?.. meanwhile try to hunt down the BMC 1800 manual online..

[ditchcrawler]

I was just watching Quest on TV and they rebuilt a TR6 when finished the filled the cooling system with this http://www.evanscoolants.co.uk/Coolants/Automotive/vintage_cool_180which will last the life of the car. Bit of a faf changing as they had to flush with a special fluid to remove all traces of water

[Sea Dog]

If we need to add a fair bit then we will have new anti - corrosive stuff right?

Since you said your coolant had a blue tinge, if your concentration is insufficient according to your tester, add concentrated blue antifreeze. This is both antifreeze and anti corrosion. You may need to drain some existing coolant out to add it. Dispose of this old coolant as advised earlier.