Seastoke
Well-Known Member
Can you see your generator supply connector
Fuel tank leak
- Thread starter Bouba
- Start date
Bandit
Well-Known Member
If the tank is suspecting leaking diesel I would not pressurise it otherwise you could blow a lot of diesel out if the leak is below diesel level.
IIRC tanks are tested to no more than about 2.5psi? Do not give it 8 bar from a compressor 116psi.
You say the tank is aluminium has it ever sat in salt water in the bilge?
How old is the boat? Have you ever had any fuel bug? Fuel bug in aluminium tanks can be a real problem as can seawater corrosion.
IIRC tanks are tested to no more than about 2.5psi? Do not give it 8 bar from a compressor 116psi.
You say the tank is aluminium has it ever sat in salt water in the bilge?
How old is the boat? Have you ever had any fuel bug? Fuel bug in aluminium tanks can be a real problem as can seawater corrosion.
Seastoke
Well-Known Member
What if we report you for discharging diesel in the Med , the Merkel police will find it.
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Bouba
Well-Known Member
Yes, it comes from a stopcock on top of the tank. The pipes (return also goes to the top of the tank) then run in plain sight and then through the bulkhead to the lazaret when the generator is fitted
Bouba
Well-Known Member
I have always pumped it into containers and disposed of responsibly. We would be mortified if we ever polluted the Med
Seastoke
Well-Known Member
I suppose the easiest is , empty tank if it stops it’s the tank
Bouba
Well-Known Member
Thank you, that’s good advice about the tank pressure !
The tank is aluminum, it sits a good few inches above the bilge and we have never had sea water ingress. The worst previous leak was from the calorifier a good few years ago and we lost all out fresh water but that was pumped out instantly by the bilge pump.
Never have had any sign of water or bug in the fuel. I treat it and all our used fuel filters look brand new.
Bouba
Well-Known Member
Yes, I thought of that. There’s about 300 litres in it. I haven’t drained it so far because the time before last, I only got a cup full after a couple of days so I thought it might be stopping. But after l left it for over a week I pumped out about six litres
Bandit
Well-Known Member
The newest aluminium tank I have seen corroded through from the inside with fuel bug was six years old. A french production line boat about 50ft.
Bouba
Well-Known Member
Ok my tank is about six years or so old but there’s no sign of corrosion anywhere (that I can see) but I’ve never had any bug. And yes it’s a French production boat
Bandit
Well-Known Member
The one I saw corroded through at the bottom from the inside where water sat, it attacked the weld. Fuel bug is acidic and corrodes aluminium. We replaced the tank with a stainless unit.
Bouba
Well-Known Member
The problem is that it depends how deep the fuel pick up is in the tank, there could be anything sloshing around the bottom of the tank. Anyhow, tomorrow I am off to the boat an will get as much information that I can gather before my back gives out
DavidJ
Well-Known Member
My tank is SS but I know on previous boats to mine (and mine is 2002) that Sealine had problems with Al tanks. I assumed Al tanks were a thing of the past.
I guess it’s how and what they are mounted on.
I guess it’s how and what they are mounted on.
Robin
Well-Known Member
I have only just seen this thread so may have missed what many have said. We had a diesel leak from our port tank right after topping both of our tanks up for winter, the tanks were linked at the time as that aids faster filling without blowback. Our leak was traced to the fuel gauge sender unit where a new one had been installed 6 months earlier by an outside contractor to our usual folk. Apparently he had installed only half of the 'sandwich' flange seal supplied which had made his job much easier. At that time the tank was reading full but was not totally brim-full so the new sender did not leak, however when we filled both tanks brim-full and they were linked via a balancing pipe, the poorly installed sender seal leaked. We were initially made aware by the marina lock operator as we returned from filling as he saw we were pumping red diesel out as we went through the lock, via the auto bilge pump. Our problem was easily enough fixed by our regular yard engineers who fitted a new sender unit again and this time did it properly. Initially they pumped out 40-50 litres which dropped the level enough to stop the leak on the top of the tank whilst new parts were obtained. they then replaced the fuel taken out so overall we had lost maybe just 5 litres or so overboard via the bilge pump before it was switched off. Our regular engineers corrected the bodge job at no cost to me for parts or labour.
edited to add. our tanks are stainless,1000litres each and were fitted new along with new engines back in 2000 'ish. (boat dates from 1986)
edited to add. our tanks are stainless,1000litres each and were fitted new along with new engines back in 2000 'ish. (boat dates from 1986)
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Bouba
Well-Known Member
We have no history of any work done to the tank. And so far I can’t find any fittings that are not on the top of the tank.I have only just seen this thread so may have missed what many have said. We had a diesel leak from our port tank right after topping both of our tanks up for winter, the tanks were linked at the time as that aids faster filling without blowback. Our leak was traced to the fuel gauge sender unit where a new one had been installed 6 months earlier by an outside contractor to our usual folk. Apparently he had installed only half of the 'sandwich' flange seal supplied which had made his job much easier. At that time the tank was reading full but was not totally brim-full so the new sender did not leak, however when we filled both tanks brim-full and they were linked via a balancing pipe, the poorly installed sender seal leaked. We were initially made aware by the marina lock operator as we returned from filling as he saw we were pumping red diesel out as we went through the lock, via the auto bilge pump. Our problem was easily enough fixed by our regular yard engineers who fitted a new sender unit again and this time did it properly. Initially they pumped out 40-50 litres which dropped the level enough to stop the leak on the top of the tank whilst new parts were obtained. they then replaced the fuel taken out so overall we had lost maybe just 5 litres or so overboard via the bilge pump before it was switched off. Our regular engineers corrected the bodge job at no cost to me for parts or labour.
Bouba
Well-Known Member
I’m only guessing my tank is aluminum by its appearance. Tomorrow I will do a scratch test. It’s not definitive but hopefully it will be obvious
Robin
Well-Known Member
As in our case also, but the sender unit flange seals wrongly fitted did not stand up to the extra pressure of tanks filled right to the top. The first/original tank sender was replaced because it stopped working.
AndieMac
Well-Known Member
Also crevice corrosion if the tank sits on rubber anti-chaffing blocks underneath, a chemical reaction is created between the alloy and rubber. This is old news though, you would think newer boat builders would be all over this by now.
Bouba
Well-Known Member
That’s interesting, I didn’t know. I thought LandDrovers had rubber between the steel and aluminum. Mind you that would explain a few things about LandRovers
BruceK
Well-Known Member
I'll take my Land Rover over a French boat thank you very much 
What I would check is the return line for over pressure and squirting from a connection. 60 litres is about an hours run time which as far as I can tell is around your usual fare.
What I would check is the return line for over pressure and squirting from a connection. 60 litres is about an hours run time which as far as I can tell is around your usual fare.