Fuel tank leak

[Bouba]

bloody excuses bouba! whining and excuses to actually doing something

Do I feel bad? Yes I bloody do! Because I know people like you would just roll up your sleeves and do the job. Hell, there are some here (and I know because they write to me) who even if their legs fell off would just drag themselves into the engine room and do the work.
Yes, I’m a lightweight ??I know.
I think I do good work, but only because I spend a lot of time thinking and researching.......

 

[Mr Googler]

Do I feel bad? Yes I bloody do! Because I know people like you would just roll up your sleeves and do the job. Hell, there are some here (and I know because they write to me) who even if their legs fell off would just drag themselves into the engine room and do the work.
Yes, I’m a lightweight ??I know.
I think I do good work, but only because I spend a lot of time thinking and researching.......

Thinking is for after

 

[Bouba]

Removing the sender tells you that there's some fuel left in the tank but you knew that already. I think you kept a note of fuel collected and level reported.

I assume that you must have disconnected the pipes by now. I would say that is the single most important task, much higher priority than unscrewing the sender and should be an easy task.

1. A continuing leak from an isolated tank means that the tank is leaking.
2. No leak means the leak was downstream OR the tank level has dropped enough to stop the leak.

If the leak stops then you add fuel to the isolated tank to see if the leak starts again.

I think you mentioned in #235 that the leak might have stopped because the diesel had thickened at low temperature. I imagine you won't have winter spec. fuel left in the tank but would be very surprised if it's cold enough in South of France to have much impact on diesel flow rate.

I dipped the tank because I never felt my fuel gauges told the real story so, I thought why not. Each time I go to the boat I have a short list of jobs.
And I will disconnect the pipes on my next visit !
The temperature has occasionally got down to 2 or 3 degrees but of course it won’t freeze. But as always, the first thing I do is pump the hull and determine how much I’m losing per day

 

[burgundyben]

Do I feel bad? Yes I bloody do! Because I know people like you would just roll up your sleeves and do the job. Hell, there are some here (and I know because they write to me) who even if their legs fell off would just drag themselves into the engine room and do the work.
Yes, I’m a lightweight ??I know.
I think I do good work, but only because I spend a lot of time thinking and researching.......

Yeah...but...I've spent more time in A&E.

 

[Mistroma]

I dipped the tank because I never felt my fuel gauges told the real story so, I thought why not. Each time I go to the boat I have a short list of jobs.
And I will disconnect the pipes on my next visit !
The temperature has occasionally got down to 2 or 3 degrees but of course it won’t freeze. But as always, the first thing I do is pump the hull and determine how much I’m losing per day

Excellent plan, data is very useful and might even be worth trying to plot loss vs. time just out of interest. I seem to remember you saying you had pumped out a lot initially, possibly 50 litres. No idea how long it took for 50 litres to leak but it did sound as if the leak had slowed considerably recently. Approx. 50 litres in a short time would make me think it was the tank because it would be difficult not to see that amount leaking from engine or generator. A slow steady drip could be anywhere and more difficult to spot.

Any fuel leak will slow and stop eventually when the level gets close to the level where the leak is located. I'm not surprised that the leak appears to have slowed as the level reduces. A drop of a few degrees is not going to affect the flow in the slightest and lower fuel level is likely to be the cause of any reduction in rate of fuel loss.

 

[Bouba]

Excellent plan, data is very useful and might even be worth trying to plot loss vs. time just out of interest. I seem to remember you saying you had pumped out a lot initially, possibly 50 litres. No idea how long it took for 50 litres to leak but it did sound as if the leak had slowed considerably recently. Approx. 50 litres in a short time would make me think it was the tank because it would be difficult not to see that amount leaking from engine or generator. A slow steady drip could be anywhere and more difficult to spot.

Any fuel leak will slow and stop eventually when the level gets close to the level where the leak is located. I'm not surprised that the leak appears to have slowed as the level reduces. A drop of a few degrees is not going to affect the flow in the slightest and lower fuel level is likely to be the cause of any reduction in rate of fuel loss.

At the peak it was about half a litre a day, now it’s a quarter. But when I first started pumping out from under the liner in the deepest part of the hull, I got a huge amount out. Now that must have been months worth and probably at a faster flow rate. Because if I had any fuel in the hull I’m sure the bilge pump would have dumped it at sea and there was never any fuel from my boat.

 

[BruceK]

It's not something stupid like a displaced breather pipe / fillup pipe is it? Could you have slowly been dumping in a litre or less everytime you've filled the boat and only now detecting it as it has worked its way through?

 

[Bouba]

It's not something stupid like a displaced breather pipe / fillup pipe is it? Could you have slowly been dumping in a litre or less everytime you've filled the boat and only now detecting it as it has worked its way through?

I did fill up just before the drip became a gush. But I thoroughly pump out the hull with every visit and it just refills

 

[Mistroma]

At the peak it was about half a litre a day, now it’s a quarter. But when I first started pumping out from under the liner in the deepest part of the hull, I got a huge amount out. Now that must have been months worth and probably at a faster flow rate. Because if I had any fuel in the hull I’m sure the bilge pump would have dumped it at sea and there was never any fuel from my boat.

I had the impression that it was much faster and dropped to a smaller fraction now. Obviously that's not the case. I don't think I'd ever refer to it as a gush. I think you mentioned pumping out 6 litres after a week initially and had previously mentioned removing 50 litres. I suspect that gave me the incorrect impression that there had been a very substantial reduction in the rate.

6 litres a week would be around 860mls/day and you updated that to 500mls/ day.

860 mls / day approx. 10-12 seconds between drips
500 mls / day approx. 17-22 seconds between drips
250 mls / day approx. 35-43 seconds between drips

These are VERY rough estimates to give a feel for what you'd be looking for IF there was a visible drip from engine or generator.
There isn't a standard size of drip (depends on lots of factors, shape of object, surface tension, specific gravity, etc.). I hope it gives a rough idea to help if you were using a tissue to detect a leak.

Even if a leak was weeping from an engine it would appear as a drip at the lowest point nearby. Engines don't sit on the hull, there's always a gap and you'd see a drip on tissues left under the engine within minutes. If you think you would have picked up a leak at that rate then it provides more ammunition for a leaky tank.

I suspect you would would have found the leak by now unless it was weeping or dripping from a hidden point. Isolating the tank becomes an obvious thing to try as already mentioned.

I hope your back improves. I usually find that the pain appears days after whatever caused it and I often can't remember what I did to trigger it. But back pain and poor memory both come with age so not exactly a revelation.

 

[stelican]

At the peak it was about half a litre a day, now it’s a quarter. But when I first started pumping out from under the liner in the deepest part of the hull, I got a huge amount out. Now that must have been months worth and probably at a faster flow rate. Because if I had any fuel in the hull I’m sure the bilge pump would have dumped it at sea and there was never any fuel from my boat.

I am surprised that no one on board had remarked about a smell of fuel.

 

[Bouba]

I had the impression that it was much faster and dropped to a smaller fraction now. Obviously that's not the case. I don't think I'd ever refer to it as a gush. I think you mentioned pumping out 6 litres after a week and had previously mentioned removing 50 litres. I suspect that gave me the incorrect impression that it was been a substantial reduction in the rate.

6 litres a week would be around 860mls/day and you updated that to 500mls/ day.

860 mls / day approx. 10-12 seconds between drips
500 mls / day approx. 17-22 seconds between drips
250 mls / day approx. 35-43 seconds between drips

These are VERY rough estimates to give a feel for what you'd be looking for IF there was a visible drip from engine or generator.
There isn't a standard size of drip (depends on lots of factors, shape of object, surface tension, specific gravity, etc.). I hope it gives a rough idea to help if you were using a tissue to detect a leak.

Even if a leak was weeping from an engine it would appear as a drip at the lowest point nearby. Engines don't sit on the hull, there's always a gap and you'd see a drip on tissues left under the engine within minutes. If you think you would have picked up a leak at that rate then it provides more ammunition for a leaky tank.

I suspect you would would have found the leak by now unless it was weeping or dripping from a hidden point. Isolating the tank becomes an obvious thing to try as already mentioned.

I hope your back improves. I usually find that the pain appears days after whatever caused it and I often can't remember what I did to trigger it. But back pain and poor memory both come with age so not exactly a revelation.

When I first noticed it fuel was collecting on the liner under the engine. It’s molded to be a drip tray. I found that the fuel inlet/outlet port on the side of the engine was weepy. I nipped it up, cleaned up the liner and thought that was that. But after a few days there was fuel (a cupful) in the liner drip tray. But I couldn’t trace the leak. The engine is dry, I’ve stood next to the engine at full revs and it’s dry. But the small amount of fuel kept collecting (but some weeks it was there and others it wasn’t. After filling the tank with about 200 liters, that’s when it started to smell and become unpleasant.
With the boat on the hard (so the trauma of it being craned out) i started to pump out large volumes. The drip tray under the engine has not refilled.
So my theory is, that the leak is coming from the tank. It’s no longer flowing aft towards the engine and collecting in the drip tray like when it was in the water. Instead, on it’s cradle at a different angle, it’s leaking forward (where I can’t see it) then it somehow finds a gap in the liner and goes straight down into the hull, from where I pump it out at the deepest part of the keel

 

[BruceK]

I did fill up just before the drip became a gush. But I thoroughly pump out the hull with every visit and it just refills

Yes but that could be residual flow through the liner. I have a liner too and if I spill a cup of oil it can take me a season of cleaning before it's all out.

 

[Bouba]

Yes but that could be residual flow through the liner. I have a liner too and if I spill a cup of oil it can take me a season of cleaning before it's all out.

Anything is possible. But we were using the boat, and staying on her, not long before, so if there was already a substantial leak, then we would have smelt it. The flow has definitely increased after she was taken on to the hard. I checked the bilge where ever I could and everything forward of the fuel tank bulkhead is as dry as a bone with no residual fuel.
My next trip I will check the bilge under the lazaret, to see if it’s dry or not.

 

[RAI]

When you were filling the tank, was the nozzle a tight fit in the filler pipe? It could be that the tank was over- pressured by the pump, long enough to split a seam.

 

[Bouba]

When you were filling the tank, was the nozzle a tight fit in the filler pipe? It could be that the tank was over- pressured by the pump, long enough to split a seam.

Interesting. The nozzle was of course placed fully in, there is a breather pipe and the tank had a bit more than 100 L in it and I added 200, in a 800 L tank. Also, on our ports fuel dock, there is a €100 limit per fill, so it takes three goes to add the fuel, so the nozzle is removed at least twice during the fill.
But interesting idea..

 

[Seastoke]

Bite the bullet ,i will give you 2oo euro for the engine , stick a motor in a few batteries change name to Tessee solved

 

[BruceK]

Bite the bullet ,i will give you 2oo euro for the engine , stick a motor in a few batteries change name to Tessee solved

Trust you to be a party stopper!

 

[Poignard]

How about posting some photos Boobs? Photos of the tank, I mean, not of you looking lost and anxious.

Then we can advise you where to apply the angle grinder, wrecking bar, large hammer etc.

 

[vas]

How about posting some photos Boobs? Photos of the tank, I mean, not of you looking lost and anxious.

Then we can advise you where to apply the angle grinder, wrecking bar, large hammer etc.

what are you asking, are you new here?

Bouba is quite happy posting pics of SoF beaches to p1ss off the ones living in the UK but not so of his own boat.
Ah, also posts nice pics of real Bouba

 

[AndieMac]

It's not something stupid like a displaced breather pipe / fillup pipe is it? Could you have slowly been dumping in a litre or less everytime you've filled the boat and only now detecting it as it has worked its way through?

I’ve seen this happen before, on the filler deck fitting where the clamped hose to the fuel tank gradually slides away from the tail/barb.
When the tank fills the fuel runs back down the inlet hose where it has created a gap due to years of pushing hose nozzles into deck fittings, then into the bilge.
Why would anybody think a filler hose would come away from a fitting tucked up under the deck that nobody would ever see?
More than likely a combination of the factory worker forgot to tension the hose clamps in the awkward to get at location and years of pushing the hose nozzle into the deck fitting, and making contact with the hose.