Where is all the coolant going?

[MtB]

 

 

23 hours ago, BlueStringPudding said:

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?

 

 

Air in the skin tank. As the engine and the skin tank heat up, air will expand and expel water on an open-vented cooling system. Then when the engine is turned off and it all slowly cools down, the trapped air will cool down and contract, leading to the water level in the open header tank to drop as water replaces the reducing volume of air.

 

 

 

2 minutes ago, Tony Brooks said:

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.

 

Tony yes I saw but I didn't initially understand what you meant, but I do now. 

 

You mean the CH header tank simply collects any water expelled past the spring cap instead of it being dumped in the bilge or overboard? 

 

[Bee]

I don't really understand the picture. The pressure cap (??) on that tank(?) has a pipe going off to the right that tee's off to a vertical pipe. If that vertical pipe has coolant in it then presumably water would flow from the tank if you removed it- or if it is connected to the tank overflow then if  pressure cap lifts to release pressure  coolant will flow into the vertical pipe.  Its all a bit puzzling and probably irrelevant to your problem but I reckon there might be a lot to be said for an air cooled engine - Good luck!

Edited February 5 by Bee

[ditchcrawler]

21 minutes ago, Tony Brooks said:

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.

I agree

[Tony Brooks]

28 minutes ago, MtB said:

 

 

 

 

Air in the skin tank. As the engine and the skin tank heat up, air will expand and expel water on an open-vented cooling system. Then when the engine is turned off and it all slowly cools down, the trapped air will cool down and contract, leading to the water level in the open header tank to drop as water replaces the reducing volume of air.

 

 

 

 

Tony yes I saw but I didn't initially understand what you meant, but I do now. 

 

You mean the CH header tank simply collects any water expelled past the spring cap instead of it being dumped in the bilge or overboard? 

 

 

Yes, that is exactly what I mean, and a slight weep on the engine could take months/years to show up, and it might do it with the symptoms described.

16 minutes ago, Bee said:

I don't really understand the picture. The pressure cap (??) on that tank(?) has a pipe going off to the right that tee's off to a vertical pipe. If that vertical pipe has coolant in it then presumably water would flow from the tank if you removed it- or if it is connected to the tank overflow then if  pressure cap lifts to release pressure  coolant will flow into the vertical pipe.  Its all a bit puzzling and probably irrelevant to your problem but I reckon there might be a lot to be said for an air cooled engine - Good luck!

 

I think the idea may be to allow the engine to be pressurised and to use the CH header tank to top up minor engine leaks. To do that, the pressure cap must have a rubber seal immediately under the cap to make it airtight. Then, as the engine cools, the contracting coolant will draw liquid from the header tank. Be that coolant expelled by the previous expansion or fresh liquid to make up for any small leaks. I think it may be hire fleet think to minimise breakdowns, but complicates things for private owners unless they understand it.

[BlueStringPudding]

Thanks everyone. Update:

 

Mon 5th Feb
Header tank empty by the morning. Filled it up. 
@tree monkey checked engine bay and pipes for leaks. Couldn't find anything. Thinks the red coolant pipe valves to/from the Eber were not fully closed. He closed them. 
Ran engine for a few hours. Header tank remained full throughout engine run.

I can't remember what time he turned the engine off but some time later - 6pm - header tank level just starting to go down
7.30pm header tank empty.
7.40 I refilled header tank with coolant.
8.40pm header tank level down by about an inch 
9pm header tank empty. Refilled.
10.15pm header tank still full.  

I went to bed 

 

Tues 6th Feb 

9am header tank still full!!!!! 😮😀

 

I'm not going to count my coolant chickens until they're hatched, but I have some ponderances that I'm curious about:.

 

@booke23 I intentionally didn't use any hot water last night after your idea about the coil in the calorifier. Could this be related to why the header tank, after a few refills last night, has finally stopped emptying? (Asking because I didn't fully understand the dynamics of how using hot water would increase coolant leak inside the calorifier. But I would like to understand it. Thanks) Incidentally, Tree Monkey and I tasted the tap water from the hot tap before running the engine yesterday and couldn't taste any coolant or see any colour. It doesn't mean there is no leak from one of the coils only that it wasn't obvious from the domestic water. 

 

@MtB Following on from your suggestion that the coolant is emptying from the header tank to refill a space that ought to have more coolant in it, I kept monitoring and refilling the tank last night over several hours until the level stopped going down on its own. It did eventually stop! The fact that it still hasn't emptied overnight supports that theory. Assuming it doesn't all go horribly wrong after I run the engine later, do you (or anyone else) know how I could have lost so much coolant when there isn't any *obvious* leak? I checked the header tank in December and it was full, so this emptying header tank phenomenon has only started within the last 2 months, and has been symptom-free despite running the engine a few times a week, until the discovery three days ago of the boiling/steam/burnt coffee smell/Pud panic incident. In the spirit of preventing it happening again, if it's been a very slow leak/evaporation of coolant over many months or years, why did it only show now do you think? 

 

@tree monkey Thank you for twiddling me knobs yesterday. It may turn out that the Eber pipes not being fully off might have caused the whole thing. If it was that, any coolant leaking out was ruddy sneaky not to have left signs below the Eber on the swim tank area, but I suppose it might have evaporated off if that gets hot. 🤔

 

Someone above (Sorry, can't see which post it's in otherwise I would tag you) suggested I work out how much fluid has gone into the header tank till it finally stopps emptying itself. 

Last night I put in about 750ml coolant till the tank stopped emptying.

The day before about a litre in total of water throughout the day and night (it never stopped emptying though) 

The first day - the day it cooked -  I kept topping it up hoping to cool it all down. So some of this coolant and water would have ended up going down the overflow pipe into the bilge. But I reckon that day I put in about a litre and a half thought the day. 

As this morning is the first time the header tank hasn't emptied while the engine is off, let's say it has taken a maximum of 3250ml (excluding what went down the overflow) to get the header tank to finally stay full. That seems like a huuuge amount of coolant to be missing from something 😮

 

Anyway, time will tell if it all disappears again after another engine run/cool down later today.

----------

Some related but not really pertinent info for anyone interested in my header tank set up:

Tree Monkey showed a photo of where the coolant pipe T's off from the header tank to both the Eberspacher and the engine. The header tank was built not only with an overflow pipe but also an auto fill mechanism, like a teeny tiny toilet cistern (but without a lid) When I bought the boat, I (eventually) traced a slow leak in the domestic water system to this auto fill valve. A "plumber" from a boatyard that shall remain nameless came to replace it (long time ago now) but when he came he turned out to be an electrician! He didn't know what he was doing and when I got home from work I found he had replaced half of the auto-fill valve only. This changed the problem from a slow leak to a continuously filling header tank that filled faster than it could empty through the overflow! Anyway, since then, the on/off knob on the auto-filler side has been permanently in the Off position and the header tank has to be checked and topped up manually. It's no great bother but isn't how the system was designed to work.  Had the auto fill been working, it's unlikely that  the coolant would have run dry/steamed/smelled like burnt coffee (although the coolant would have become increasingly diluted over time). The first I would have known about any leak or missing coolant would have been the domestic water pump cycling unexpectedly when the header tank needing more top ups than usual. Anyway, I always thought it was a clever idea for a hire boat to have a self-filling header tank that keeps both the engine and the heating happy - especially as the header tank was installed behind a very heavy interior OSB wall, making it very unaccessible to hirers (good) and to future owners like me (bad). I replaced that wall panel with a hinged wooden one some years ago so at least the tank can be accessed without screwdrivers and Geoff Capes' physique. I'll try to put a photo below of the header tank set up, just for the curious among you. 

 

The pipe with the white writing leads to the T-junction piping in the engine bay that Tree Monkey posted yesterday. 

Edited February 6 by BlueStringPudding

[Tony Brooks]

That does not look like a very large header tank and you have an overflow, so if there is a volume of air in the engine cooling circuit it JUST MIGHT be that the air overfills the header tank that then drains the surplus so when it cools down all the coolant returns to the engine leaving a low level. I am not sure that any air bubbles flowing around the system would not build up the that cylindrical "header" and may airlock in the horizontal and vertical pipe running to the CH header tank.

 

I think that once the system is stone-cold and before refilling, it would be worth taking the pressure cap(s) off to see how full the cooling system is.

also, can you route the header tank overflow into a bucket so you can assess the volume of any coolant lost as the engine gets hot.

[Eeyore]

A quick and easy (if a bit messy) way to isolate the two systems.

Clean the pipe with a soft damp cloth. Cut the pipe where marked in red, then fit two end stops.

This is better/easier/safer bet than trying to dismantle and reuse what could be either mark one or mark two Hep2O fittings.

Typical end stop :

https://www.screwfix.com/p/jg-speedfit-plastic-push-fit-stop-ends-15mm-2-pack/94176

inserts:

https://www.screwfix.com/p/hep2o-smartsleeve-stainless-steel-push-fit-pipe-inserts-15mm-10-pack/3158f

cutting tool:

https://www.screwfix.com/p/faithfull-3-42mm-manual-plastic-pipe-cutter/587gc

 

All of these bits are often found lurking at the bottom of other boaters "useful drawer", so not necessarily a big outlay. 

[BlueStringPudding]

1 hour ago, Tony Brooks said:

That does not look like a very large header tank and you have an overflow, so if there is a volume of air in the engine cooling circuit it JUST MIGHT be that the air overfills the header tank that then drains the surplus so when it cools down all the coolant returns to the engine leaving a low level.

Any thoughts as to why that would have only started happening recently? 

 

I am not sure that any air bubbles flowing around the system would not build up the that cylindrical "header" and may airlock in the horizontal and vertical pipe running to the CH header tank.

 

I think that once the system is stone-cold and before refilling, it would be worth taking the pressure cap(s) off to see how full the cooling system is.

@tree monkey did that yesterday. Please see his earlier post. Perhaps he could elaborate for clarity about the water level in the cylindrical header? 

 

1 hour ago, Tony Brooks said:

also, can you route the header tank overflow into a bucket so you can assess the volume of any coolant lost as the engine gets hot.

Next time a kindly neighbour or monkey goes into the engine bay, I'll ask them to do that. (I'm not mobile enough to get in and out of there myself these days. Sorry, it makes investigating stuff like this rather slow and annoying for all concerned

 

Thanks Tony. Responses in bold above. 😊

[Tony Brooks]

14 minutes ago, BlueStringPudding said:

 

 

Thanks Tony. Responses in bold above. 😊

 

You may well have a header tank on the engine as well as the CH one and the cylindrical thing. I doubt Black Prince would not have fitted a "standard" water jacket exhaust manifold cum header tank. If there is a filler cap on it then it needs a higher pressure one than the one on the cylindrical thing.

 

I could not find a post from TM where he described what he found in the cylindrical thing and or manifold filler on the engine.

 

 

18 minutes ago, BlueStringPudding said:

Any thoughts as to why that would have only started happening recently? 

 

On the present evidence, I don't think the Eber has anything to do with it unless it's heat exchanger is leaking, but turning the valve off should stop that. I also think that saying that the CH header tank serves both the engine and Eber is not particularly helpful, because the two circuits do seem to be separated by the pressure cap seal on the cylindrical thing.

 

Assuming my understanding of the system is something like correct.

 

I think that there are two possibilities, but one may well lead into the other.

 

1. A very slow loss of coolant over a long time period that has been masked by the rather strange setup until a considerable quantity of coolant had leaked from the system, but if this was the case I don't understand why the engine did not overheat. The loss of a lot of coolant could lead to 2.  Possible causes are a leaking water pump or perforated core plug. Apart from antifreeze or rust staining, both can be difficult to find while minor because engine heat tends to evaporate the liquid away.

 

2. Air or gas trapped in the cooling system somewhere almost always leads to the loss of coolant because air/gas expands so much more than coolant, there by displacing even more water. How any air got in I have no idea, but it could build up over time from air entrapped in the topping up liquid. If it were gas, it could be as a result of some kind of microbial or chemical reaction in the system or possibly a very minor leak through the head gasket. Being an ex hire boat, my guess is that skin tank is more than ample for the job.

 

Certainly try to measure how much, if any, coolant is vented via the CH header tank overflow. If it is roughly the same as the amount you top up, then it probably is gas/air trapped in the system.

 

Definitely manipulate all the coolant hoses, especially any that have upward or downward bows in them, so air can get back into the manifold (if it has a filler), the cylindrical thing, or the skin tank. Then with a full CH header tank, bleed the skin tank, topping up as required.

 

 

I think that your system has a lot more excess coolant capacity than most private boats so it would take longer for it to become depleted.

 

 

 

 

 

[Tracy D'arth]

31 minutes ago, Tony Brooks said:

 

 

 

I think that your system has a lot more excess coolant capacity than most private boats so it would take longer for it to become depleted.

 

 

 

 

 

Quite possibly and that would result in more spilling out when it heats up if it is filled to the top.

[BlueStringPudding]

31 minutes ago, Tony Brooks said:

 

 

I could not find a post from TM where he described what he found in the cylindrical thing and or manifold filler on the engine.

 

 

Sorry, maybe @tree monkey just said it to me and didn't write it down here. He told me it had water in it and he seemed unconcerned about it.

As for the manifold, I don't even know what a manifold is let alone it's filler, so I will leave that for the monkey man to elaborate on. 

2 minutes ago, Tracy D'arth said:

Quite possibly and that would result in more spilling out when it heats up if it is filled to the top.

 

Which brings me back to why has the header tank never emptied before now? Its auto-fill valve has been turned off for maybe a decade. 🤔

What could be going on that might bite me on the bum at a later date, I wonder? 

[tree monkey]

Additional pictures @Tony Brooks

 

[Tony Brooks]

Thanks tree monkey, so no water jacket and filler on the exhaust manifold and any air/gas that finds its way into the engine should run straight up into the cylindrical thing, which is good. It still sounds like heated air causing a lot of coolant to be vented when hot, so try t measure the volume expelled from the CH header tank overflow and compare with what was previous put back to fill t up.

 

Cheers.

[booke23]

4 hours ago, BlueStringPudding said:

@booke23 I intentionally didn't use any hot water last night after your idea about the coil in the calorifier. Could this be related to why the header tank, after a few refills last night, has finally stopped emptying? (Asking because I didn't fully understand the dynamics of how using hot water would increase coolant leak inside the calorifier. But I would like to understand it. Thanks) Incidentally, Tree Monkey and I tasted the tap water from the hot tap before running the engine yesterday and couldn't taste any coolant or see any colour. It doesn't mean there is no leak from one of the coils only that it wasn't obvious from the domestic water. 

 

A leaking calorifier coil could have various symptoms depending on the specifics of your setup. One scenario might be that it won't leak while the domestic water system is pressurised (ie while the water pump is on) but does so slowly when it's off....perhaps even back filling your domestic water tank in the bow if the header tank is high enough. This could account for the total lack of evidence of a water leak. 

 

In the absence of any other evidence, It might be worth isolating or bypassing the calorifier coil just to rule it out. 

[Tony Brooks]

55 minutes ago, BlueStringPudding said:

As for the manifold, I don't even know what a manifold is let alone it's filler, so I will leave that for the monkey man to elaborate on. 

 

Now we have the photo you do not have one, that simplifies things a lot.

 

56 minutes ago, BlueStringPudding said:

Which brings me back to why has the header tank never emptied before now? Its auto-fill valve has been turned off for maybe a decade. 🤔

What could be going on that might bite me on the bum at a later date, I wonder? 

 

I think the answer is that whatever the cause is, it has only started within the last few months. Be that a coolant leak or build up of air/gas in the cooling system. Both need ruling out. If I am correct, there is unlikely to be anything coming back to bite you.

2 minutes ago, booke23 said:

 

A leaking calorifier coil could have various symptoms depending on the specifics of your setup. One scenario might be that it won't leak while the domestic water system is pressurised (ie while the water pump is on) but does so slowly when it's off....perhaps even back filling your domestic water tank in the bow if the header tank is high enough. This could account for the total lack of evidence of a water leak. 

 

In the absence of any other evidence, It might be worth isolating or bypassing the calorifier coil just to rule it out. 

 

True, but I think seeing if it is venting any coolant would be a better first step, and only isolate the calorifier both pipes if it is not venting any water. However, as most cooling systems run at sub 15psi and most domestic water systems run at 30pi plus, any coil problem is more likely to show itself as the header tank overflowing while the domestic system is pressurised, engine running or not.

[Eeyore]

1/ The green is the (dry) exhaust manifold.

2/ The black is the inlet manifold.

3/ The yellow are the hoses to the calorifier coil.

4/ The red is a temporary loop of hose should you need to disconnect the yellow hoses to take the calorifier coil out of circuit for testing. It allows you to run the engine normally, but you'll need a kettle for hot water.

A continuous discharge of water from the disconnected yellow hoses, accompanied by the water pump running, is a fair indication that the coil is leaking.

You can of course use the redundant coil fed from the eberspacher to effect a repair if needed. Just blank off the leaking coil.

[magnetman]

 

I wonder if the Boat has hit or been hit by something hard at some point. That could cause a crack in the calorifier coil. 

 

 

 

[BlueStringPudding]

*sigh" after a promising night and day, this evening the header tank has lost its coolant again.

Here's how it's played out.

Tues 6th Feb
9am header tank still full from yesterday 
3.15pm header tank still full, started engine. 
6pm turned engine off. Header tank still full but as I walked past it I heard 2 bloops as if air bubbles might have come up to the surface. Didn't see any though. 
7pm header tank level gone down half an inch. 
8pm header tank empty.

 

 

I'll top it up again now and make note of the quantity.

 

41 minutes ago, Eeyore said:

1/ The green is the (dry) exhaust manifold.

2/ The black is the inlet manifold.

3/ The yellow are the hoses to the calorifier coil.

4/ The red is a temporary loop of hose should you need to disconnect the yellow hoses to take the calorifier coil out of circuit for testing. It allows you to run the engine normally, but you'll need a kettle for hot water.

A continuous discharge of water from the disconnected yellow hoses, accompanied by the water pump running, is a fair indication that the coil is leaking.

You can of course use the redundant coil fed from the eberspacher to effect a repair if needed. Just blank off the leaking coil.

Thanks Eeyore. 

[BlueStringPudding]

Thought I would update this again. 

 

Tues 6th Feb

8pm header tank was empty Refilled (blooping noises of air in pipes) 

10.43pm only a little more coolant gone. Topped up once more but no blooping noises this time. 
(Added approx 670ml coolant today)

 

Wed 7th Feb
Only a little coolant gone. Topped up approx 300ml. Didn't run engine today.

 

Thurs 8th Feb
No coolant lost from header tank.  Didn't run engine today 

 

Fri 9th Feb
No coolant lost from header tank. Didn't run engine today 

--------

Tomorrow I'll run the engine again and see what happens. 🤔

 

 

Edited February 9 by BlueStringPudding

[Tony Brooks]

It seems that you have not yet monitored any overflow from the header tank, so that makes further diagnosis and comment difficult, but the talk of glugging might suggest there was air/gas in the system. If there is/was then the amount of water expelled as it is heated will gradually get less. There is also no mention of bleeding/venting the skin tank that again makes everything more difficult.

 

If you are filling the header tank right up to the overflow, then it will always vent coolant as the system eats up and then APPEAR to have lost coolant when it cools again. Once you are sure everything is back to normal, fill the header tank to the overflow. get the system nice and hot. Allow it to get really cold and note the coolant level. That will be the topping up level.

[Suzi]

Hiya, not sure if this will help but I have ex black prince with exactly same auto fill engine header tank when i moved aboard 9 years ago .... the first thing I had done was to remove the autofill connection from the engine header tank as I didn't like the idea of anti freeze anywhere near my domestic water pipes...

 

so I put antifreeze/water in my engine header tank if and when needed and I top up the eberspacher header tank (same as yours) separately as and when needed....

 

not sure that helps at all 🤔 but just have a feeling separating the auto fill may help?? 

 hope you get it sussed 🙏

[BlueStringPudding]

21 minutes ago, Tony Brooks said:

It seems that you have not yet monitored any overflow from the header tank, so that makes further diagnosis and comment difficult, but the talk of glugging might suggest there was air/gas in the system. If there is/was then the amount of water expelled as it is heated will gradually get less. There is also no mention of bleeding/venting the skin tank that again makes everything more difficult.

 

If you are filling the header tank right up to the overflow, then it will always vent coolant as the system eats up and then APPEAR to have lost coolant when it cools again. Once you are sure everything is back to normal, fill the header tank to the overflow. get the system nice and hot. Allow it to get really cold and note the coolant level. That will be the topping up level.

Correct. Those things have to wait until I have a willing bilge-diving volunteer in the right place at the right time. 

 

But thanks for the advice. They're on the to-do list. 

[Tony Brooks]

24 minutes ago, BlueStringPudding said:

Correct. Those things have to wait until I have a willing bilge-diving volunteer in the right place at the right time. 

 

But thanks for the advice. They're on the to-do list. 

 

I fully understand, basically thats why we sold the boat, I was getting to arthritic to do the maintenance.

 

If you have managed to vent the system, you may find only the overfill (as described above) is vented and that is normal.

[Eeyore]

@BlueStringPudding are you able to move the deck boards for a few photos from above?

 

A photo showing where the pipe marked in yellow goes? Best guess is that point "C" connects in some way to what looks like the skin tank, marked in red at the bottom of the photo.

 

A photo showing where "B" and "A" go to/come from.

 

Does @tree monkey remember what type of cap (marked in green) is fitted, pressure or plain?

 

Edited February 10 by Eeyore

[BlueStringPudding]

Unfortunately not on my own, they're way too heavy for me. I don't know if any of my burly neighbours are around this weekend. If they are, I'll ask them to help.

 

What do you need photos of other than what Tree Monkey has already photographed here? I'll try to get the correct areas in the pics for you.