Where is all the coolant going?

[BlueStringPudding]

My boat has suddenly developed a problem. The header tank (which feeds everything - the engine/calorifier/radiators) is emptying, but we don't know where to. It's never done this before.

 

When I re-fill the header tank and run the engine, the header tank remains full. However the water disappears a little while after the engine is turned off. This I discovered for the first time yesterday when a gawd awful smell and whisp of what may have been steam appeared above the cupboard inside the back cabin where the header tank is located. I panicked, topped the empty tank up (the pipes below it and somewhere in the engine bay making bloop-bloop air bubble noises), and I turned the engine off. I kept topping up the header tank till the blooping noises stopped and it held on to the water level. However when I checked back later the header tank was empty again.

 

So today I tried a bit of an experiment.  I topped up the empty header tank and ran the engine from 3.50pm. I turned the engine off at 7.20pm and the header tank appeared to be at the same level. The water in the header tank and the pipe immediately below it remained cool to the touch. 

At 8pm the header tank was still full. 

At 8.30pm the header tank was half full.

At 9pm it was just a quarter full.

By the morning I expect it'll be empty because it was this morning. 

 

My neighbour had a look round the engine bay today with the engine running and not running, and with the header tank topped up and not. He couldn't see or feel any leaks anywhere. 

 

What might cause the header tank to retain its water level only while the engine is running?

 

And where might the coolant be leaking from so quickly when it's cooled?

 

Any other advice please? 

 

(For info: Engine is a Kubota, 3-cylinder, boat is a 1997 Black Prince)

 

Thanks

 

[booke23]

A leak in the calorifier heat exchanger coil? This would drop the header tank as you use hot water from the taps. Or maybe an external leak on a skin tank? 

[ditchcrawler]

I am surprised if the same header tank fills the engine calorifier and radiators. That would be a very strange set up sharing engine coolant with the radiators.

[BlueStringPudding]

5 minutes ago, ditchcrawler said:

I am surprised if the same header tank fills the engine calorifier and radiators. That would be a very strange set up sharing engine coolant with the radiators.

 

That's what I was told many years ago. There's no other header tank. The radiators and Eberspacher haven't been used in donkeys years. I imagine the radiators don't share the engine's coolant as such, but the one header tank feeds both calorifier coils. I'm guessing. 

Edited February 4 by BlueStringPudding

[booke23]

41 minutes ago, ditchcrawler said:

I am surprised if the same header tank fills the engine calorifier and radiators. That would be a very strange set up sharing engine coolant with the radiators.

 

Good point. On the beta 30 (Kubota 3 cylinder) an external header tank is optional. The engine has a built in tank like below.

 

To @BlueStringPudding some photos might help. 

 

 

Edited February 4 by booke23

[Eeyore]

@BlueStringPudding has a 3 cylinder 1700cc 03 series Kubota marinised by Black Prince, so not particularly "standard", whatever that is!

Probably need to check under the floor at the back of the boat; there's often an inspection hatch under the back steps (or nearby).

You can also go along the bottoms of the radiators and around the valves with a dry piece of kitchen paper to check for leaks.

[MtB]

7 hours ago, BlueStringPudding said:

 

That's what I was told many years ago. There's no other header tank. The radiators and Eberspacher haven't been used in donkeys years. I imagine the radiators don't share the engine's coolant as such, but the one header tank feeds both calorifier coils. I'm guessing. 

 

I don't think it can do. This would defeat the whole point of having a twin coil calorifier. 

 

Your comment about the Eber not having been used for years might however provide an explanation. The Eber water circuit will have been warmed up on a daily basis even witout you actually firing the Eber, warmed by the hot water inside calorifier in turn heated by running the engine. Over an extended period of time the water in the Eber circuit is likely to evaporate away due to the routine and repeated heating. I suspect this is why you found the header tank accepted loads of water, and issued a whisp of steam. It was the last dregs of the water in your heating system evaporating away. 

 

So in summary, I suspect your engine coolant is as well-filled as ever, and your heating system much depleted (prior to you topping it up yesterday). And you will have an engine coolant header tank somewhere else. Probably on the engine. 

 

[blackrose]

8 hours ago, BlueStringPudding said:

 

 There's no other header tank. The radiators and Eberspacher haven't been used in donkeys years. 

 

In which case you should have isolated the defunct eberspacher & central heating system from the engine cooling system and drained the CH side donkeys years ago, because the only thing that side of the system will ever do is leak.

 

What you've got is a load of extra useless pipework and radiators attached to your (working) engine that just increases the potential for leaks.

Edited February 5 by blackrose

[Bee]

The gawd awful smell and maybe a wisp of steam  sounds to me like a leak (probably inaccessible) and the rubbery / rotten eggs smell of antifreeze / rubber hoses and all that horrible stuff. I would start there. As for header or expansion tanks that would indeed be unusual. Take a look at the engine and follow all the pipes, if a couple disappear into the boat itself then follow them, they probably go into the calorifier and that will probably explain some of what is happening. I don't suppose you are overfilling the engine header tank are you? 

[BlueStringPudding]

3 minutes ago, Bee said:

The gawd awful smell and maybe a wisp of steam  sounds to me like a leak (probably inaccessible) and the rubbery / rotten eggs smell of antifreeze / rubber hoses and all that horrible stuff. I would start there. As for header or expansion tanks that would indeed be unusual. Take a look at the engine and follow all the pipes, if a couple disappear into the boat itself then follow them, they probably go into the calorifier and that will probably explain some of what is happening. I don't suppose you are overfilling the engine header tank are you? 

 

Thanks Bee. The header tank can't be overfilled because it has an overflow pipe that takes excess into the outer area of the engine bay where it would eventually be expelled by the bilge pump. 

 

The smell on that first day was grim, like burnt coffee. I've not smelled it since refilling the header tank. 

[BlueStringPudding]

3 hours ago, blackrose said:

 

In which case you should have isolated the defunct eberspacher & central heating system from the engine cooling system and drained the CH side donkeys years ago, because the only thing that side of the system will ever do is leak.

 

What you've got is a load of extra useless pipework and radiators attached to your (working) engine that just increases the potential for leaks.

The pipes that go to the Eber have had their valves in the off position for as many years as it's not been used.

("Should haves" aren't very helpful just at the moment. I have a problem to resolve before reflecting on lessons learned)

5 hours ago, MtB said:

 

I don't think it can do. This would defeat the whole point of having a twin coil calorifier. 

 

Your comment about the Eber not having been used for years might however provide an explanation. The Eber water circuit will have been warmed up on a daily basis even witout you actually firing the Eber, warmed by the hot water inside calorifier in turn heated by running the engine. Over an extended period of time the water in the Eber circuit is likely to evaporate away due to the routine and repeated heating. I suspect this is why you found the header tank accepted loads of water, and issued a whisp of steam. It was the last dregs of the water in your heating system evaporating away. 

 

So in summary, I suspect your engine coolant is as well-filled as ever, and your heating system much depleted (prior to you topping it up yesterday). And you will have an engine coolant header tank somewhere else. Probably on the engine. 

 

 

Thanks MtB. If it is just the Eber coolant circuit evaporating away, do you know why the header tank (if it is indeed for the Eber only) is still only retaining its water level when the engine is running? (It is as I predicted, empty again this morning and the approximate rate of emptying is described in a previous post above.) My neighbour couldn't find any leak around the Eber itself or engine. (Calorifier is possible but inaccessible to me at the moment, it'll have to be checked another time when I have help)

 

And just so I can understand it, how come the Eber header tank pipe got so hot that it stank like burnt coffee and sounded like it was boiling? Could what little Eber coolant was left really have got that hot just from passing through the calorifier (engine hadn't been running long)?  Or does it mean a leak somewhere in the Eber coolant circuit? If not necessarily a leak, should I just keep manually refilling it several times a day, or only when about to run the engine, until such a time as the fault can be found? (Coz I still need power and hot water while this is being investigated) 🤔

 

Thanks

[MtB]

1 hour ago, BlueStringPudding said:

The pipes that go to the Eber have had their valves in the off position for as many years as it's not been used.

("Should haves" aren't very helpful just at the moment. I have a problem to resolve before reflecting on lessons learned)

 

Thanks MtB. If it is just the Eber coolant circuit evaporating away, do you know why the header tank (if it is indeed for the Eber only) is still only retaining its water level when the engine is running? (It is as I predicted, empty again this morning and the approximate rate of emptying is described in a previous post above.) My neighbour couldn't find any leak around the Eber itself or engine. (Calorifier is possible but inaccessible to me at the moment, it'll have to be checked another time when I have help)

 

And just so I can understand it, how come the Eber header tank pipe got so hot that it stank like burnt coffee and sounded like it was boiling? Could what little Eber coolant was left really have got that hot just from passing through the calorifier (engine hadn't been running long)?  Or does it mean a leak somewhere in the Eber coolant circuit? If not necessarily a leak, should I just keep manually refilling it several times a day, or only when about to run the engine, until such a time as the fault can be found? (Coz I still need power and hot water while this is being investigated) 🤔

 

Thanks

 

 

Hmmm it looks like I need to read your OP again, more carefully than I did at 5am in the middle of the night! 

 

Boiler to fix in Aylesbury this afternoon and I need to get going. Will have another good look again tonight after bellringing

 

 

 

 

[tree monkey]

38 minutes ago, MtB said:

 

 

Hmmm it looks like I need to read your OP again, more carefully than I did at 5am in the middle of the night! 

 

Boiler to fix in Aylesbury this afternoon and I need to get going. Will have another good look again tonight after bellringing

 

 

 

 

I've got back today and had a look, tbh I'm as much in the dark as BSP.

 

There is a shared header tank, it feeds into the engine header (?) and the eber via 2 separate feeds but it is a shared tank.

 

It turns out the eber wasn't isolated, so I have now done that.

 

No obvious signs of and leak in the engine bay and no lingering smell beyond what a normal engine bay smells like

 

 

[rusty69]

10 minutes ago, tree monkey said:

I've got back today and had a look, tbh I'm as much in the dark as BSP.

 

There is a shared header tank, it feeds into the engine header (?) and the eber via 2 separate feeds but it is a shared tank.

 

It turns out the eber wasn't isolated, so I have now done that.

 

No obvious signs of and leak in the engine bay and no lingering smell beyond what a normal engine bay smells like

 

 

You checked the obvious, I suppose.Its not disappearing into the engine due to a head gasket failure?

[tree monkey]

2 minutes ago, rusty69 said:

You checked the obvious, I suppose.Its not disappearing into the engine due to a head gasket failure?

Yup, oil's fine, the engines ticking over now, I will check it later, but I do suspect the eber pipework has shat it's self somewhere because there's no obvious leak in the engine bay

[BlueStringPudding]

6 minutes ago, tree monkey said:

... I do suspect the eber pipework has shat it's self somewhere...

 

Steady on with the technical jargon there. I almost understood that 😄

[Eeyore]

27 minutes ago, tree monkey said:

I've got back today and had a look, tbh I'm as much in the dark as BSP.

 

There is a shared header tank, it feeds into the engine header (?) and the eber via 2 separate feeds but it is a shared tank.

 

It turns out the eber wasn't isolated, so I have now done that.

 

No obvious signs of and leak in the engine bay and no lingering smell beyond what a normal engine bay smells like

 

 

So this is a view from inside the boat looking aft?

[tree monkey]

1 minute ago, Eeyore said:

So this is a view from inside the boat looking aft?

That long tube thing with the pressure cap is on the bulkhead between engine and the cabin that is fed from the header tank, eber feed is next to it from the same header

[Tony Brooks]

This probably won't help much, but assuming the hose just below the cap running to the T where it joins the pipe running from the CH header tank to the Eber then I think it is only using the CH header tank as a convenient expansion tank. It looks as if the hose is above where one would normally expect the pressure seal to be located, allowing the engine to run pressurised but not the Eber. There is probably another seal immediately below the cap top, so if the engine ran short of coolant, it could send smell and steam into the CH header tank. However, that does not explain where the coolant is going.

[ditchcrawler]

9 minutes ago, Tony Brooks said:

This probably won't help much, but assuming the hose just below the cap running to the T where it joins the pipe running from the CH header tank to the Eber then I think it is only using the CH header tank as a convenient expansion tank. It looks as if the hose is above where one would normally expect the pressure seal to be located, allowing the engine to run pressurised but not the Eber. There is probably another seal immediately below the cap top, so if the engine ran short of coolant, it could send smell and steam into the CH header tank. However, that does not explain where the coolant is going.

Would it not suck it in as the engine cooled 

 

[blackrose]

4 hours ago, BlueStringPudding said:

("Should haves" aren't very helpful just at the moment. I have a problem to resolve before reflecting on lessons learned)

 

Except it's not just a "should have". In my opinion you need to completely isolate the redundant central heating system from your engine's cooling system as part of the solution to your problem.

 

Edited February 5 by blackrose

[Tony Brooks]

Just now, ditchcrawler said:

Would it not suck it in as the engine cooled 

 

 

It should until it sucked all the liquid out of the CH header and pipework, which I suspect may have happened, but why the engine temperature alarm/gauge did not show an overheat, I have no idea. This MIGHT be the result of a very minor coolant weep over a long period.

2 minutes ago, blackrose said:

 

Except it's not just a "should have". In my opinion you need to completely isolate the redundant central heating system from your engine's cooling system as part of the solution to your problem.

 

 

Going by the photo I think that they probably are - by the coolant pressure cap seal.

[MtB]

Well we know the water being added then seeming to disappear must be going somewhere. There two possibilites I can think of:

 

1) The system wasn't full in the first place, and the water being added is simply filling up a space in the system e.g.  a skin tank.

2) It is escaping from the system.

 

If its 1, the water being added daily will eventually fill it up and you'll find you have to stop. If its 2, then you'll be able to add water daily infinitum. 

 

So I suggest taking a careful note from now on of how much water you add, and when you add it. Then after a few days you can review the actual volume added and consider where it might be now. 

[MtB]

23 hours ago, BlueStringPudding said:

The header tank (which feeds everything - the engine/calorifier/radiators)

 

First big question. The above seems vanishingly unlikely, but I know your engine has other weird stuff about it like the starter motor right underneath (IIRC!) The cooling system on a diesel engine younger than about 50 years is usually pressurised. This usually comes about with a spring-loaded filler cap on a header tank which is usually part of the engine. Could you bung up a photo of the whole engine please, so we can see what it has in the way of heat exchanger, filler cap (if any), water pump(s) and skin tank connections? Fanx. 

 

 

23 hours ago, BlueStringPudding said:

When I re-fill the header tank and run the engine, the header tank remains full. However the water disappears a little while after the engine is turned off.

 

Second question. 

 

What happens if you re-fill the header tank and don't run the engine? Does it stay full or does some water still disappear after <how long?>

 

 

 

 

Third Q:

 

How is your engine cooled? Is it a skin tank? Is there an air vent on top of the skin tank? Can we see a photo of the whole of the skin tank please?

 

Or is it raw water-cooled? 

 

[Tony Brooks]

Mike, did you see my interpretation of the photo she posted?

 

I think the CH header tank may also be used as an expansion tank AFTER the pressure cap so not pressurised.  I think the CH tank is more like just a non-pressurised expansion tank as far as the engine coolant is concerned. No one has commented on this or tried to say I am wrong.