Water cooling skin

[Moisha]

Hi all,

 

We've got an Isuzu 42hp engine and a 60ft Liverpool narrowboat. We weretold that we are due to change the coolant/water, but nobody seems to know how to drain the water out of the skin or how much water the skin holds. And Liverpool is now, sadly, out of business, we have no one to ask! Has anyone done such a thing and do you happen to know the how and the how much?

 

Many thanks yet again,

Moisha

[alan_fincher]

Often the only way to drain will be to physically remove a bottom hose from engine to skin tank, (much like one might have drained an old vehicle).

 

There is no way of estimating how much your skin tank holds, without dimensions, as different shell builders take widely differing approaches. (Liverpool boats have often been known to skimp on skin tanks, so it may not prove to be quite as big as it ought to be!)

 

However if you measure it in each dimension, and work out it's capacity in cubic centimetres, (simple multiple length x height x "thickness"), then divide by 1000 that will be a good estimate of litres. Most water will be in the skin tank. The engine and it's heat exchanger, header tank, pipework will be far less significant by comparison, though your engine hand book may say how much coolant it holds.

 

Don't forget that the coolant you remove is very harmful, due to the anti-freeze, and must't go down normal drains or into ditches. It needs taking to a proper licensed disposal facility.

[Moisha]

Many thanks for this. It seems we will just add some water+coolant and deal with a full replacement next year. But we are certain to heed your advice.

 

Moisha

[AlanH]

Often the only way to drain will be to physically remove a bottom hose from engine to skin tank, (much like one might have drained an old vehicle).

 

There is no way of estimating how much your skin tank holds, without dimensions, as different shell builders take widely differing approaches. (Liverpool boats have often been known to skimp on skin tanks, so it may not prove to be quite as big as it ought to be!)

 

However if you measure it in each dimension, and work out it's capacity in cubic centimetres, (simple multiple length x height x "thickness"), then divide by 1000 that will be a good estimate of litres. Most water will be in the skin tank. The engine and it's heat exchanger, header tank, pipework will be far less significant by comparison, though your engine hand book may say how much coolant it holds.

 

Don't forget that the coolant you remove is very harmful, due to the anti-freeze, and must't go down normal drains or into ditches. It needs taking to a proper licensed disposal facility.

Had to remove the bottom hose to drain mine but I didn't bother with the measuring thing. I just got plent of anti-freeze and put in 5 litres of that followed by 5 litres of water then repeated I litre at a time until it was full. This actually meant that I got a higher ratio than 50/50 but that's OK.

[casper ghost]

Many thanks for this. It seems we will just add some water+coolant and deal with a full replacement next year. But we are certain to heed your advice.

 

Moisha

Hi. You just need to make sure that the antifreeze you top up with is the same colour as whst is already in the system.

Casp'

[nb Innisfree]

If you need to remove bottom hose, before replacing it try to take the trouble of fitting a tee piece into it with a drain valve and hose barb outlet then in future all you need do is fit a vacuum oil changer on the barb and open the valve. A very handy modification.

[Guest]

If you need to remove bottom hose, before replacing it try to take the trouble of fitting a tee piece into it with a drain valve and hose barb outlet then in future all you need do is fit a vacuum oil changer on the barb and open the valve. A very handy modification.

Neat

[jenlyn]

If you need to remove bottom hose, before replacing it try to take the trouble of fitting a tee piece into it with a drain valve and hose barb outlet then in future all you need do is fit a vacuum oil changer on the barb and open the valve. A very handy modification.

 

clever sod, good idea that

[system 4-50]

Had to remove the bottom hose to drain mine but I didn't bother with the measuring thing. I just got plent of anti-freeze and put in 5 litres of that followed by 5 litres of water then repeated I litre at a time until it was full. This actually meant that I got a higher ratio than 50/50 but that's OK.

My understanding is that concentrations of antifreeze in excess of 50% are NOT OK as it has a deleterious effect on hoses and such. However I am totally unable to find out where I got this idea from.

[alan_fincher]

The subject of going over 50% anti-freeze has come up before, but I don't remember it being in the context of damaging everything.

 

50% anti-freeze will provide protection against temperatures well below any likely to be encountered in a narrowb oat.

 

But it appears if you want absolutely the best protection against low temperatures with ethylene glycol based antifreeze you should actually go 70% antifreeze / 30% water.

 

That's if you need to protect to -51 degrees Celsius rather than -34 degrees Celsius!

 

Old Post

Edited September 27, 2010 by alan_fincher

[Canalwatcher]

The subject of going over 50% anti-freeze has come up before, but I don't remember it being in the context of damaging everything.

 

50% anti-freeze will provide protection against temperatures well below any likely to be encountered in a narrowb oat.

 

But it appears if you want absolutely the best protection against low temperatures with ethylene glycol based antifreeze you should actually go 70% antifreeze / 30% water.

 

That's if you need to protect to -51 degrees Celsius rather than -34 degrees Celsius!

 

Old Post

 

I changed the antifreeze on our Aqualine Manhattan which has the 42hp Isuzu and a skin tank.

 

I disconnected the skin tank bottom hose at its top end where it connects to the engine and extracted the antifreeze with a Pela suction pump by inserting the suction tube right down inside the skin tank bottom hose. Also drained the engine as per normal via the drain plug. Refilling took 26 litres.

 

Pela also made it easy to transfer old antifreeze into containers to dispose at council refuse faciity

 

Mick

[WotEver]

My understanding is that concentrations of antifreeze in excess of 50% are NOT OK as it has a deleterious effect on hoses and such. However I am totally unable to find out where I got this idea from.

This page, referring to Rotax aircraft engines, explains that a higher concentration of anti-freeze can increase the running temperature of the engine in the summer due to the increased viscosity of the mix.

 

I have no idea whether the same would hold true with a typical narrowboat cooling system.

 

Tony

[churchward]

Often the only way to drain will be to physically remove a bottom hose from engine to skin tank, (much like one might have drained an old vehicle).

 

There is no way of estimating how much your skin tank holds, without dimensions, as different shell builders take widely differing approaches. (Liverpool boats have often been known to skimp on skin tanks, so it may not prove to be quite as big as it ought to be!)

 

However if you measure it in each dimension, and work out it's capacity in cubic centimetres, (simple multiple length x height x "thickness"), then divide by 1000 that will be a good estimate of litres. Most water will be in the skin tank. The engine and it's heat exchanger, header tank, pipework will be far less significant by comparison, though your engine hand book may say how much coolant it holds.

 

Don't forget that the coolant you remove is very harmful, due to the anti-freeze, and must't go down normal drains or into ditches. It needs taking to a proper licensed disposal facility.

The previous time I changed the coolant I did as you suggest and estimated the amount. Oddly enough I changed the coolant in readiness for winter just last weekend and this time measured the amount of water/anti-freeze mix going back in to fill the system up. I don't know if this is typical but I ended up with a measurement of 23 litres which was several litres more than I originally estimated. So for a 30-50% mix I need around 10 litres of anti-freeze.

 

In response to the OP again as Alan mentions my only option is to take off the bottom hose and let the water poor into that side of the bilge (it is a self contained side that doesn't leek into other areas like to part of the bilge that the pump usually works in). I also tale out the top bleed threaded bung on the skin tank which helps all the water mix come out. I then use a hand bilge pump to pump the water into containers. As Alan says disposal needs care. The final small amount left I sponge out. It's a bit of a pain but I don't do it that often so not so bad.

Edited September 28, 2010 by churchward

[Canalwatcher]

..... my only option is to take off the bottom hose and let the water poor into that side of the bilge... (

 

Not your only option - another is to take the top of the bottom hose off where it leaves the engine which you can then hold above engine header tank level and use a suction pipe pushed down to the bottom of the skin tank as my post 11 above

 

I am assuming your bottom hose is similar diameter to mine - about 30mm

 

Mick

Edited September 28, 2010 by zodiak

[FadeToScarlet]

Not your only option - another is to take the top of the bottom hose off where it leaves the engine which you can then hold above engine header tank level and use a suction pipe pushed down to the bottom of the skin tank as my post 11 above

 

Mick

 

Or another option, if you're replacing the hoses, is to obliquely cut the end of a small copper pipe, force it into the bottom hose, and then use it to vacuum extract the contents.

 

Might be a bit too dangerous, though, with a higher risk of spillage than other methods.

[Guest]

I was going to use my wet vac when I got around to the job. Would that be dangerous?

[Gibbo]

Don't forget that the coolant you remove is very harmful, due to the anti-freeze, and must't go down normal drains or into ditches. It needs taking to a proper licensed disposal facility.

 

Who will then put it down a normal drain or into a ditch.

[Guest]

Who will then put it down a normal drain or into a ditch.

Do they? I have often wondered about this recycling stuff TBH.

[WotEver]

Do they? I have often wondered about this recycling stuff TBH.

I've seen our local 'recycling facility' recycling computers. It involves thraping the pc with a large sledgehammer until the mains transformer falls loose. Another wallop directly to the transformer will then disconnect its cables. The rest of the pc goes into the metal recycling skip, along with all the cadmium, palladium, silica, plastics etc that it contains.

 

I'm not saying they're all like this, but ours is.

 

Tony

[pquinn]

would it be possible to use the small oil extraction pump that is mounted on the engine down in to the bung on the top of the skin tank and just pump it out clean and tidy?

[nb Innisfree]

would it be possible to use the small oil extraction pump that is mounted on the engine down in to the bung on the top of the skin tank and just pump it out clean and tidy?

 

As mentioned in an earlier post a pump would need to reach to the bottom of the skin tank, not possible if it is correctly fitted with internal baffles.

[pquinn]

As mentioned in an earlier post a pump would need to reach to the bottom of the skin tank, not possible if it is correctly fitted with internal baffles.

 

 

cheers.now i understand.

 

would i be right in thinking that i refill through the expansion tank?

sorry but i am only learning this stuff.

Edited September 7, 2011 by pquinn

[WotEver]

would i be right in thinking that i refill through the expansion tank?

Yep. Leave the bleed bolt out of the top of the skin tank (assuming it has one) until water comes out, too.

 

Tony

[pquinn]

great.thanks.

[nb Innisfree]

Yep. Leave the bleed bolt out of the top of the skin tank (assuming it has one) until water comes out, too.

 

Tony

 

That's right, leave the bleedin' bolt out