BlueStringPudding

Hi all. I thought I would give you an update about the mysterious disappearing coolant. A boaty neighbour who knows his engines has recently returned to the UK after a couple of months away, and bless him, me and one other one of us pounced on him to ask for help with our respective engines! He's a great chap and has been so determined that my engine won't beat him, he's been working on it for three days so far, eliminating possible causes and in the process discovering other, possibly linked problems, and resolving them as he goes. If you want the quick answer to what we think is the main culprit, skip ahead to the last paragraph. But if you want to know what he's unpicked so far, read on: So, the problem we're trying to solve is that the coolant system appears to be losing 600ml plus slowly over about 2 hours, every time the engine cools down, as indicated by the indoor expansion tank, which is connected to the engine and Eber circuits. It's been losing coolant by emptying not through its overflow which would indicate engine overheating, but out through its lower pipework towards the engine, emptying slowly as the system cools. As you know from above, TM and another of my boaty neighbours checked around the engine and there were no obvious leaks that could account for this. Initial checks by this chap could also find no obvious leaks in or around the engine area either. His first thought that the initial overheat in February that started all this (whisp of steam, burnt coffee smell, boiling sound in the pipes) might have been caused by a sticky thermostat valve, but he was happy it was working fine. He was also happy that the head gasket was fine. He did discover an air lock or blockage in the engine coolant system though. (Coolant coming through the pipe at the top front of the engine felt very hot - but never hot enough to be pushed up into the expansion tank or out the overflow pipe from that tank into a bottle. However the return pipes from the skin tank were almost cold and might not have had water in it at all.) He blew through the pipes and skin tank and then flushed through what he could there with water, and now the engine coolant is hot but not too hot at the front, and warm at the return from the skin tank, as it should be. But... as the engine cooled after a few good runs, the expansion tank lost coolant at the same rate as before, every time. To quote him: where is all the water going!? He discovered that the alternator belt between the starter alternator and the water pump wasn't fully on. It felt tight at the top but underneath he could easily turn the pump by hand. So he repositioned the belt and tightened it up. But that was a bit of a red herring with regards to being a cause for possible overheating, because that alternator belt had been changed *after* the initial overheat in February, (the old alternator belt being toothless in places 😲 ) He checked the radiator cap and other parts, and gave any potential risky bits a once over and a clean, but still no improvement. He unblocked two tiny drainage holes in the bulkhead between the stern bilge and the cabin bilge, expecting water to come through from anything leaking the other side of the bulkhead. But there was no water, in fact his screwdriver came out dry. Also, uncovering the inspection hatch in the stern cabin floor showed no water. He eliminated the likelihood of there being a coolant leak from the calorifier by isolating it from the engine (as someone above suggested) joining two engine coolant pipes together to make a closed loop. But as the engine cooled after another couple of good runs, the expansion tank lost coolant at the same rate as before, till it was empty every time. But we still couldn't see where it was going to. Yesterday he eliminated any radiators leaking being the possible cause, by capping off the relevant Eberspacher pipe. But as the engine cooled after another run, guess what? The expansion tank still lost coolant at the same rate as before until it was empty. So his attention went back to the engine area. There was a horizontal line of scale a few inches above the bottom of the skin tank, the baseplate next to it being currently dry. He scraped that scale away and a while later it revealed a slow weeping leak from near the weld. Running the engine made steam come from there, confirming there is a pinhole coolant leak from the skin tank into the bilge. The weeping skin tank leak is extremely slow, just damp, so not the location of 600ml plus coolant lost from the expansion tank every time the engine cools, but I'm pleased it's been discovered. The boat is booked in for some work at the boatyard next month so repairing that is now on their to-do list. Meanwhile, the expansion tank is still losing coolant and being refilled repeatedly, but there's still no water sloshing about anywhere. This morning, he again checked the pressurised header tank that is immediately above the engine and he could tell that the level had gone down a little since yesterday. Again, no puddles anywhere, and the expansion tank in the cabin has emptied overnight as usual. So he undid the pressurised radiator cap as well as the pipes that link the expansion tank inside the cabin to it. When I then filled the indoor expansion tank with water it should have drained out where he was standing by the pressurised engine tank, but it didn't. The pipe between the two was blocked. So after a few hefty puffs he blew the pipe clear and I flushed it through with water Once the expansion tank was full and the connecting pipe clear, it was obvious that the radiator cap even when not under pressure was dripping. When checked last month and again this weekend, the radiator cap appeared to be working fine, but now it's obvious that it just doesn't seal properly. So his prevailing theory about where all this coolant has been going is that it may have been coming out of the knackered radiator cap as steam and/or drips, because the pipe from it into the expansion tank was almost but not entirely blocked - so coolant couldn't expand into the expansion tank. But the coolant wasn't collecting in puddles on the baseplate or anywhere else either to make this obvious. And although the engine thermostat appears to be working fine, on the off-chance that it may have stuck shut in the past, I've ordered a new one and he's going to replace it as a "belt and braces" way to ensure all this shouldn't happen again. So fingers crossed that the case of the mysterious disappearing coolant will have been solved. But we shall see when the parts are replaced! Thanks to TM, everyone here and my three contributing neighbourinos for their help with this. Let's hope these two replacement parts and all the unblocking of pipes and budging of airlocks has fixed it. 🤞

I've done that too, in the past

Hi. I need to find someone who can repair my cruiser stern deck hatches. They're two large steel hatches and the four hinges have rusted through. The hinges need replacing. Ideally I would like someone whose work comes recommended and who can travel to my boat on the Cov. Any recommendations, please?

Thanks Eeyore. A kindly neighbourino opened the deck hatches for me this morning. (No I didn't think to take my phone but any pics wouldn't have been any better than those above) Judging by eye, I think those two pipes that you've marked are joined directly without a second skin tank in-between. Also the swim ledge on that side doesn't have the telltale indentation that the skin tank on the other side does. @Tony Brooks I've wedged a bottle under the header tank over flow pipe to measure if some comes out next time. The overflow pipe was almost horizontal so when I tilted it downwards there was a trickle of coolant that came out (possibly just as a result of my slightly overfilling the tank earlier this week, who knows) There is currently about an inch of coolant remaining in the bottom of the header tank. I'm not sure whether to top it up to just below the overflow outlet again before I next run the engine?

In the vain and desperate hope that I'm mistaken, I'm going to try and find a way to trail that header overflow pipe into a container or something. I've just got to wait till I've got help.

I ran the engine for 2 hours this morning. Now the engine is cooling down, the header tank coolant level is dropping. And although I can't reach it I can see from above the end of the overflow pipe from the (Eber/joint) header tank and the area below it. Both appear dry, suggesting that's probably not where the coolant is going. (I'll get a closer look another time when I'm feeling a bit better) Thanks for the advice, Tony. The overflow pipe for the header tank just empties onto the shelf of the swim/skin tank so what doesn't trickle off into the wet bilge, I'm guessing might just evaporate from the heat of the skin tank. (I'm guessing?)

Bear with me @Eeyore. Could only get one side of the deck hatch up and now it's stuck there, so I've been hanging upside down with a torch and phone trying to take photos under the other deck hatch. I've rather broken myself but at least I didn't drop the phone or torch in, or indeed myself in! Below is a pic of the (yellow) pipe that goes into the (red) skin tank, plus the other paraphernalia above and to the right of the engine. The only other pipe I can see attached to the skin tank is this fat one towards the stern: Any sort of bleed valve isn't obvious to me from above the deck, but you guys might see it coz you know what you're looking for. Oh blimey. That I'm afraid is even less visible from above the closed hatch. I've tried to take a couple of pics but my hands are shaking now so they're very blurry. Sorry. I can't really tell if that pipe leads to another skin tank or not.

Yes, I know from memory that the (yellow) pipe leads to the (red) skin tank. I've no idea about the location of a bleed point for it though (which tells you how likely it is to have been bled, unless that's ever been done by someone servicing the engine in the past, it's clearly not been done by me). I'll go see if any of my beefy-grr neighbours are about and willing to hoist up the deck lids for a photo op. Brb.

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.

My boat originally came with curtains over the windows. These were tucked behind a horizontal rod across the bottom of the windows. The curtains were very mouldy in the folds of the fabric. So I decided to go for blinds. I have a roller blind in the bathroom, held flat against the wall by a single tiny screw-in hook and eye, which is quite subtle. And there are wooden Venetian blinds in all the other cabins. These are held by 2 of the same tiny screw-in hooks on the bottom window frame, lined up with the vertical threads running through each blind. The threads loop over the hooks and these hold the blinds parallel to the wall and are hidden by the lowest wooden slat. The slats still twist open and closed without having to unhook them.

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.

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. 🤔

*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. Thanks Eeyore.

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. 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?

Thanks Tony. Responses in bold above. 😊