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Replacing engine coolant


jetzi

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I topped up our engine coolant today with fresh water and it struck me that I don't know how long it has been since the coolant was changed, nor what kind of antifreeze was used or in what ratio. Since we are about to hit some really cold temperatures I think it would be best to drain the cooling system and replace the coolant.

 

Note that we will live aboard throughout winter and run the engine twice a day, occasional weekends away notwithstanding, so this isn't really "winterising" in the same sense as those who store their boats.

 

My engine is a Beta Marine 38 (Kubota BV1505) 1.5 litre. (The information plaque is illegible but the engine model is stated on the original Black Prince specification sheet, and it looks like the picture, except it's blue instead of red.) According to the manual I downloaded, this engine has a coolant capacity of 7 litres. I presume this is the volume of the coolant in the actual engine as skin tanks surely vary and in some applications don't exist, right? So I measured the external size of the skin tanks inside the engine bay which came out at 1250x480x60mm each, which would be a maximum of 36 litres each! Secondly, there is a calorifier fitted, and as far as I can tell it's a closed pipe circuit with no header tank or any clear way to empty it and top it up.

 

I had a quick look at antifreeze on Amazon (where else) and it seems there are two main types - red and blue. This one says it is specifically for boats, if that makes any difference.

 

This leaves me with a few questions:

1. What is the best antifreeze to use?

2. How can I calculate how much I need?

3. Should I try to change the calorifier circuit as well?

4. What do I do with the old coolant?

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8 minutes ago, ivan&alice said:

I topped up our engine coolant today with fresh water and it struck me that I don't know how long it has been since the coolant was changed, nor what kind of antifreeze was used or in what ratio. Since we are about to hit some really cold temperatures I think it would be best to drain the cooling system and replace the coolant.

 

Note that we will live aboard throughout winter and run the engine twice a day, occasional weekends away notwithstanding, so this isn't really "winterising" in the same sense as those who store their boats.

 

My engine is a Beta Marine 38 (Kubota BV1505) 1.5 litre. (The information plaque is illegible but the engine model is stated on the original Black Prince specification sheet, and it looks like the picture, except it's blue instead of red.) According to the manual I downloaded, this engine has a coolant capacity of 7 litres. I presume this is the volume of the coolant in the actual engine as skin tanks surely vary and in some applications don't exist, right? So I measured the external size of the skin tanks inside the engine bay which came out at 1250x480x60mm each, which would be a maximum of 36 litres each! Secondly, there is a calorifier fitted, and as far as I can tell it's a closed pipe circuit with no header tank or any clear way to empty it and top it up.

 

I had a quick look at antifreeze on Amazon (where else) and it seems there are two main types - red and blue. This one says it is specifically for boats, if that makes any difference.

 

This leaves me with a few questions:

1. What is the best antifreeze to use? My engine came with the blue stuff so I have stuck with this (different types don't mix well.)

2. How can I calculate how much I need? Measure skin tank and work out volume. Add a couple of gallons  for engine pipework, heat exchanger etc. Think mine is about 7 gallons of coolant. I use a 33% strength mix, which I mix before adding to system.

3. Should I try to change the calorifier circuit as well? If possible.

4. What do I do with the old coolant? Our local recycling centre has taken mine in the past.

 

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Why not test your còolant? Take a sample in a yoghurt pot or similar and put it in the freezer.  If it does not set hard your còolant is fine down to minus 15 C.  If it sets hard you need to  change ALL the còolant.

N.

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17 minutes ago, BEngo said:

Why not test your còolant? Take a sample in a yoghurt pot or similar and put it in the freezer.  If it does not set hard your còolant is fine down to minus 15 C.  If it sets hard you need to  change ALL the còolant.

N.

True this is a good test for antifreeze property. Problem with old stuff is that it can lose its anti corrosion properties. I understand that corrosion inhibitor can be added to existing coolant.

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2 hours ago, catweasel said:

1. What is the best antifreeze to use? My engine came with the blue stuff so I have stuck with this (different types don't mix well.)

2. How can I calculate how much I need? Measure skin tank and work out volume. Add a couple of gallons  for engine pipework, heat exchanger etc. Think mine is about 7 gallons of coolant. I use a 33% strength mix, which I mix before adding to system.

3. Should I try to change the calorifier circuit as well? If possible.

4. What do I do with the old coolant? Our local recycling centre has taken mine in the past.

 

1. Thanks, I have heard that you can't mix the different types. Are they more than just "red" and "blue"? If I start from scratch, i.e. empty the coolant and maybe flush with water, which is the best kind for my engine? Any recommended brands? (Would rather spend more on this for a better product).

 

2. I measured my skin tanks from inside the engine bay, they look like they occupy the whole of the face of the swims. I worked them out to be 36 litres each, plus the 7 litres that according to the manual are in the engine, plus the estimated 2 litres of the calorifier loop gives 81 litres (18 gallons). That seems like a lot more than yours - I probably overestimated on the skin tanks by taking the external measurement?

 

As for the mix, the engine manual recommends 33-50% mix, so I plan to err towards the 50% side so that any dilution will still end up with a strong enough solution.

 

2 hours ago, BEngo said:

Why not test your còolant? Take a sample in a yoghurt pot or similar and put it in the freezer.  If it does not set hard your còolant is fine down to minus 15 C.  If it sets hard you need to  change ALL the còolant.

N.

This is such a brilliantly obvious idea I have no idea how come I didn't think of this. Now all I have to do is find a freezer ?

 

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9 minutes ago, ivan&alice said:

 

1. Thanks, I have heard that you can't mix the different types. Are they more than just "red" and "blue"? If I start from scratch, i.e. empty the coolant and maybe flush with water, which is the best kind for my engine? Any recommended brands? (Would rather spend more on this for a better product).

 

2. I measured my skin tanks from inside the engine bay, they look like they occupy the whole of the face of the swims. I worked them out to be 36 litres each, plus the 7 litres that according to the manual are in the engine, plus the estimated 2 litres of the calorifier loop gives 81 litres (18 gallons). That seems like a lot more than yours - I probably overestimated on the skin tanks by taking the external measurement?

 

As for the mix, the engine manual recommends 33-50% mix, so I plan to err towards the 50% side so that any dilution will still end up with a strong enough solution.

 

This is such a brilliantly obvious idea I have no idea how come I didn't think of this. Now all I have to do is find a freezer ?

 

Creep into a supermarket with it and bury it under a load of ice cream or something in one of their freezers and retrieve it the next day.

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1 hour ago, ivan&alice said:

 

1. Thanks, I have heard that you can't mix the different types. Are they more than just "red" and "blue"? If I start from scratch, i.e. empty the coolant and maybe flush with water, which is the best kind for my engine? Any recommended brands? (Would rather spend more on this for a better product).

 

2. I measured my skin tanks from inside the engine bay, they look like they occupy the whole of the face of the swims. I worked them out to be 36 litres each, plus the 7 litres that according to the manual are in the engine, plus the estimated 2 litres of the calorifier loop gives 81 litres (18 gallons). That seems like a lot more than yours - I probably overestimated on the skin tanks by taking the external measurement?

 

As for the mix, the engine manual recommends 33-50% mix, so I plan to err towards the 50% side so that any dilution will still end up with a strong enough solution.

 

This is such a brilliantly obvious idea I have no idea how come I didn't think of this. Now all I have to do is find a freezer ?

 

With thorough flushing you should be OK to change type I would think. The type in my car is ten year stuff.

I have only one skin tank so your estimate of double the amount might not be too far off. Probably somewhere in between (my estimate is only from memory.)

You can get a hydrometer from Halfords, Ebay etc for buttons  that will tell you the strength of the current mix. This sort of thing: https://www.ebay.co.uk/itm/PROFESSIONAL-ANTI-FREEZE-COOLANT-LEVEL-TESTER-Radiator-Hydrometer-Car-Vehicle/192740461017?hash=item2ce03a09d9:g:B-EAAOSwA3dYDe2c:rk:7:pf:0

I did put 50% in a couple of changes ago, but felt it was overkill. Does mean you can just top up with water though until next change.

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5 hours ago, BEngo said:

Why not test your còolant? Take a sample in a yoghurt pot or similar and put it in the freezer.  If it does not set hard your còolant is fine down to minus 15 C.  If it sets hard you need to  change ALL the còolant.

N.

What a clever idea!

 

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As a rough comparison my beta 43 with a calorifier and twin skin tanks holds about 30 litres of coolant.  As to disposal, I phoned our water company and the tech person asked me not to take it to the recycling centre as she was sure some of them don’t know what they are doing and dump it down the storm drain, so I took it to a local car repair place.  Paid them a tenner to put it in to their waste coolant tank.

 

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The quantity will depend on the size of your skin tank. My coolant system holds 45 litres and my central heating system holds 25 litres. Yours will differ as no two boats are the same. Buy more antifreeze than you need mix it as you fill it and measure the system capacity as you fill it. You can return the unused antifreeze for a refund.

 

I changed my blue antifreeze for red Ford 10 year antifreeze. I flushed it through with clean water before refilling. I took the old antifreeze down to my local tip for disposal.

Edited by cuthound
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