Flushing and draining engine coolant

[Scholar Gypsy]

This is one of the engine maintenance jobs I have not done yet. I have been keeping an eye on the effectiveness of the anti-freeze, and also added some rust inhibitor a year or two ago. But I don't think I should put it off any longer...

 

So I would be interested in views on the following proposal, following a reading of various posts here and also of Tony Brooks' website.

 

This schematic ...

cooling_schematic.pdf

... shows on the first page the current set up: calorifier run off the bypass circuit, and then once the thermostat opens coolant flows through the header tank/manifold heat exchanger and into the skin tank. It's a Mitsubishi 4 cyl diesel.

 

I'm not sure of the tank's capacity, but the temperature is always very stable when the engine is running.

 

I am proposing (second page) to add a T-junction to the return pipe from the calorifier (this is convenient as there is some 15mm copper pipe available to cut into, and then add a couple of ball valves (they should cope with the pressure in the system in normal use, 12 psi I think?) on the drain and on the bypass circuit (with the latter, B, open for normal running). I would then do the following:

1. Remove pressure cap
2. Open drain valve (A)
3. Add water to header tank - using a hose under pressure if necessary
4. Keep going until the water comes out clear
5. So I have now flushed the skin tank.
6. Close drain valve A.
7. Close bypass valve B
8. Start engine
9. Open drain valve A
10. Keep header tank full
11. Run the engine for a couple of minutes, adding water to the header tank, to flush the engine and the calorifier circuit. Stop before the thermostat opens. The clear water in the skin tank is now flushing the engine.
12. Open valves A and B to drain as much water as possible. I may need to disconnect one of the hoses to the skin tank and use a Pela pump to get more water out
13. It may be necessary to crack the thermostat housing to let the water drain out of the engine?
14. Add antifreeze and water, noting Tony's point that it will mix well, using the squeezy thing to make sure I have enough anitfreeze.
15. Bleed skin tank, if I can find a bleeding point under the bed.

Interested in any views, if people have spare time over the Christmas break. Many thanks in advance.

[Sea Dog]

Well, I certainly can't think of a way to make it any more complicated without adding even more valves and pipework!

 

I just drain the system, refill it with water to flush, drain it again and either repeat if it's still 'orrible or fill it with my chosen coolant mix. Mine takes about 33 litres, most of which is the skin tank.

 

Mind you, I also took the easy route and did it in the summer and I used 5 year stuff so I didn't have to do it again for a good while. Your method is proper Ninja - you weren't a Royal Marine, we're you?

[Scholar Gypsy]

Well, I certainly can't think of a way to make it any more complicated without adding even more valves and pipework!

 

I just drain the system, refill it with water to flush, drain it again and either repeat if it's still 'orrible or fill it with my chosen coolant mix. Mine takes about 33 litres, most of which is the skin tank.

 

Mind you, I also took the easy route and did it in the summer and I used 5 year stuff so I didn't have to do it again for a good while. Your method is proper Ninja - you weren't a Royal Marine, we're you?

 

The answer to the last question is "no". Although it's fair to say (see this posting) that I quite enjoy complex systems, provided they work.

 

I should also have said that at present not very much water comes out when I disconnect the pipes to the skin tank, I think this is because (at the point they are accessible) they are both pretty close to the level of the top of the tank. So at present I can't "just drain the system".

[Sea Dog]

Ah yes, I saw that.... and downloaded the link tooin fact! Very thorough.

 

Back on this topic, I drained all my system down, inc calorifier, through the engine drain cock, but the bottom hose should do too. I then used a cheapo syphon pump to empty the skin tank. I think that's pretty much the norm but, of course, systems vary. Hope it goes OK for you

[rustydiver]

Hummmm I tried to drain mine a few weeks ago, engine drain tap was ok, couldn't remove the top plug in the skin tank it was solid. So going to fit a drain vale inline on the bottom hose next year.

Where do you get the valve too? I've looked but havnt found any, need to double check the size but I think the internal dia off the pipe is 100mm.

[Scholar Gypsy]

Hummmm I tried to drain mine a few weeks ago, engine drain tap was ok, couldn't remove the top plug in the skin tank it was solid. So going to fit a drain vale inline on the bottom hose next year.

Where do you get the valve too? I've looked but havnt found any, need to double check the size but I think the internal dia off the pipe is 100mm.

 

Mine is closer to 30mm - you can just see it at the top of this photo, near to the corner of the blue crate.

 

I am planning to add the drains etc to a section of 15mm copper pipe, because it's easier to do, and also enables me to separately flush the skin tank and the calorifier. ETA: you can see the copper pipe on the right of the photo, along the bulkhead.

Edited December 21, 2015 by Scholar Gypsy

[Sea Dog]

Hummmm I tried to drain mine a few weeks ago, engine drain tap was ok, couldn't remove the top plug in the skin tank it was solid. So going to fit a drain vale inline on the bottom hose next year.

Where do you get the valve too? I've looked but havnt found any, need to double check the size but I think the internal dia off the pipe is 100mm.

You're gonna need that top plug you couldn't shift Rusty. It's the bleed valve to let the air out when you've refilled the skin tank.

[Bloomsberry]

How important is it to remove all the old coolant from the system ?

You could just remove 2/3 of the coolant in the system then refill with a 50% anti freeze solution.

 

This combined with the 1/3 still in the system would mean the anitfreeze would be diluted down to 33%.

If this was deemed ok then you could probably leave the antifreeze in the calorifier circuit intact ?

This would need to be done in summer during cruising season to give the coolant chance of mixing well before the onset of winter (unless you're planning on embarking on a winter cruise of course).

[Bee]

I drain my engine every year and the stuff in it is really horrible, yes I use antifreeze and there is an anode in it but it always comes out looking orange and nasty, dunno why, maybe 'cos there is copper pipe in the system and electrolysis is eating my engine.

[Scholar Gypsy]

Well, I certainly can't think of a way to make it any more complicated without adding even more valves and pipework!

 

I just drain the system, refill it with water to flush, drain it again and either repeat if it's still 'orrible or fill it with my chosen coolant mix. Mine takes about 33 litres, most of which is the skin tank.

 

Mind you, I also took the easy route and did it in the summer and I used 5 year stuff so I didn't have to do it again for a good while. Your method is proper Ninja - you weren't a Royal Marine, we're you?

 

I'd be interested to know what make of 5 year antifreeze you used.

 

I see bluecol do both red and blue products, though both seem to be methanol free ethylene glycol products. The colour seems to relate to how long the corrosion protection lasts for, not the antifreeze properties (which I think lasts more or less for ever if methanol free).

[cuthound]

I'd be interested to know what make of 5 year antifreeze you used.

 

I see bluecol do both red and blue products, though both seem to be methanol free ethylene glycol products. The colour seems to relate to how long the corrosion protection lasts for, not the antifreeze properties (which I think lasts more or less for ever if methanol free).

You are correct, the antifreeze part is glycol, which lasts indefinitely.

 

I use Ford Super P!us Premium antifreeze, (less than £20 per 5 litres) which lasts up to 10 years I had a 10 year old Ford Focus with this in it, and drained some antifreeze and put some steel, aluminium and coppper in in. A year later they were still untarnished.

[Sea Dog]

 

I'd be interested to know what make of 5 year antifreeze you used.

 

I see bluecol do both red and blue products, though both seem to be methanol free ethylene glycol products. The colour seems to relate to how long the corrosion protection lasts for, not the antifreeze properties (which I think lasts more or less for ever if methanol free).

I use the red stuff from www.eurocarparts.co.uk which is reasonable value. They do ready to use (50%) or concentrate. It's usually cheaper to buy over the net on click and collect than in store. They deliver too. Use Extra10 in the discount code box at checkout for an extra 10% off. You're right about the life being based the corrosion inhibitors.

[Scholar Gypsy]

You are correct, the antifreeze part is glycol, which lasts indefinitely.

 

I use Ford Super P!us Premium antifreeze, (less than £20 per 5 litres) which lasts up to 10 years I had a 10 year old Ford Focus with this in it, and drained some antifreeze and put some steel, aluminium and copper in in. A year later they were still untarnished.

 

Thanks - helpful. That comes pre-mixed which is also helpful.

 

The bluecol product is a bit more expensive per 5l bottle, but can be diluted 1:1 (I will live with -17^oC protection rather than -36^oC) ....

I use the red stuff from www.eurocarparts.co.uk which is reasonable value. They do ready to use (50%) or concentrate. It's usually cheaper to buy over the net on click and collect than in store. They deliver too. Use Extra10 in the discount code box at checkout for an extra 10% off. You're right about the life being based the corrosion inhibitors.

 

thanks very much, looking at that now as well. I think I've got enough info now. I now just need to do the job...

[Chewbacka]

I think the red stuff contains organic acid corrosion inhibitors which are for aluminium radiators etc. It is not meant for use with copper. So if you have copper pipe especially in contact with other metals I would call the coolant tech line to check it is ok to use.

[ditchcrawler]

Has anyone tried waterless coolant in a boat engine, its supposed to last for ever http://www.rimmerbros.co.uk/Item--i-GRID800085

[Scholar Gypsy]

So the only task now is to decide how much antifreeze to buy, ie what is the capacity of the system. I know this is a how long is a piece of string question.

 

I reckon that the air space in the header tank (the Bowman heat exchanger) is about 0.5 litre, so with a 70 degree temp difference (15 to 85) that means total capacity of the system is roughly 40 litres assuming all the water heats up to 85 degrees, which of course it doesn't.

 

That seems quite a lot - but I know I have quite a beefy keel tank. So I was planning to buy 20 litres of concentrate and see how I get on (diluting 50:50). Does that seem credible? Sea Dog reports a similar number...

 

change in volume = volume x 0.0002 x (change in temperature deg C)

[cuthound]

I counted out the cold coolant (and central heating system contents), before buying antifreeze.

 

Cooling system capacity was 40 litres and central heating system capacity was 25 litres. Other boats will not be the same, but will probably be in the order of these capacities. My boat is 60 foot long, with 3 rads and a heated towel rail, powered by a Beta 43.

[Sea Dog]

Just check the price of pre diluted versus concentrate and deionised water. I went for concentrate and deionised, but even at 33% the price difference was not what I expected.

[pearley]

You are correct, the antifreeze part is glycol, which lasts indefinitely.

I use Ford Super P!us Premium antifreeze, (less than £20 per 5 litres) which lasts up to 10 years I had a 10 year old Ford Focus with this in it, and drained some antifreeze and put some steel, aluminium and coppper in in. A year later they were still untarnished.

Just had our coolant replaced after 8 years. That in the engine came out almost as clean as if new though that might have been because I've had a leak and so been topping it up about 1/2 litre a month. The generator tank was rusty coloured and quite a lot of much came out when flushed. We have 2 belly tanks that form the engine beds and cool the engine and a standard skin tank for the generator. I measured both tanks and calculated the capacities, adding on the engine capacities and bit for the hoses. I needed 60 litres of antifreeze for a 50/50 mix!

 

I too used Ford Super-Plus Premium. I searched online and found Vospers at Plymouth who sold it for £15 per 5 litres plus delivery. Just in case I got my calculations wrong(I hadn't) I bought another 5 litres from the local Ford dealer - £30.02!

[Scholar Gypsy]

Just check the price of pre diluted versus concentrate and deionised water. I went for concentrate and deionised, but even at 33% the price difference was not what I expected.

Good point - I see what you mean...

[jenevers]

I have copper pipes in part of my genny cooling system. Never occurred to me that it could cause galvanic problems, until I read this topic.

So which anti freeze is the best to prevent any reaction? Anyone know?

Maybe I should replace it with steel pipe.

[Scholar Gypsy]

I have copper pipes in part of my genny cooling system. Never occurred to me that it could cause galvanic problems, until I read this topic.

So which anti freeze is the best to prevent any reaction? Anyone know?

Maybe I should replace it with steel pipe.

 

An interesting question!

 

Surely all calorifiers contain copper pipes? In my system there is no specific bonding between the engine and the calorifier (the equivalent of earthing straps that you find in domestic heating systems), but that is not the same as saying there is no electrical contact between the two ...

[Sea Dog]

I have copper pipes in part of my genny cooling system. Never occurred to me that it could cause galvanic problems, until I read this topic.

So which anti freeze is the best to prevent any reaction? Anyone know?

Maybe I should replace it with steel pipe.

I hope there's some expert advice available on this, because I've looked (briefly) at this subject before and found speculation but little evidence. The mixing of copper components, chiefly pipework, is fairly common in automotive circles and appears to be thought to be ok because of the anti corrosion element in anti freeze. I also found advice for fishing boats about pipework going brittle through galvanic action, but the issue seemed to be a problem when excessive vibration or stress was also present and use of annealing and isolation with rubber hose seemed to be the answer. If there was a big issue here I'd have expected to find more (and possibly argument about earth bonding!) but, like I said, it would be interesting to have an expert view.

[Chewbacka]

My coolant was due for a change, so I did a bit of study as I would rather use a long life coolant and found this that advises against using long life OAT (organic acid technology) coolants in systems containing yellow metals

https://www.opieoils.co.uk/pdfs/tech-articles/coolant-antifreeze.pdf

So I bought some traditional blue stuff.

 

However some coolant manufacturers now specifically claim that their formulation is ok for use with copper & Brass etc

https://www.cumminsfiltration.com/pdfs/product_lit/americas_brochures/LT36237.pdf

 

So In a couple of years time when it is due for change I will change to long life suitable for yellow metals.

So as all long life coolants are not the same, if you are not sure all I can suggest is that you check the data sheet of the product you wish to use/are using and if it is not clear give their tech department a call.

[cuthound]

I beleive Surecal calorifiers are made of stainless steel, including the coils - could be wrong though.