Fuel Tank Leaks

[NigelW]

Has anyone any experience with leaking diesel tanks?
I have, what appears to be an aluminium tank, with all the hoses/connections on the top, which are clean and dry, but a trickle of fuel eminating from the bottom of the locker.
We cannot see the bottom of the tank or the forward side. To remove it means cutting a bulkhead - ugh!! and spoiling the aft cabin.
The original spec for the yacht stated 'stainless steel fuel tank', seems like estate agent syndrome.
If there are any ideas out there, before I rip the boat apart, please let me know.

 

[Chris_Stannard]

Chances are you have low grade stainless which is not particularly rust proof. Only sensible answer is to replace and fit a cock at the bottom so you can drain the water build up out. This is an unfortunate fact of life, both from the return stray line, water in diesel you buy, and possibly a leaky deck filler. All fuel tanks get water in and it must be drained regularly. It also helps to keep the tank full, though few of us do that.
You will obviously also need an inspection hatch, to get at the drain, but since you are going to cut the bulkhead you might as well fit tha at the same time.

No other medium to long term solution that I know.

Chris Stannard

 

[oldharry]

The problem with S/S is that it is so hard that when it is welded quite abit of stress can be locked into the weld as it cools down, particularly if the welder is not very skilled at his job. If it is then subjected to regular flexing or vibration - as from the engine - the weld can fail quite quickly.

In the same way any brackets or lugs welded to the tank can fatigue the steel plate and break away.

No easy answers here that I know of if the tank is innacessible. Is it possible for a contortionist with a small hand mirror to view the inaccessible parts of the tank before you start radical surgery, just to see if there is any means of accessing the leak in situ?

Otherwise you might consider whether a new tank could be installed more easily somewhere else aboard rather than dismantling half the boat to get at the old one?

 

[NigelW]

Thank you for your input.
There does not seem to be any alternative to ripping the yacht apart. We ahve tried to insert small people into smaller spaces, the only result was unrepeatable words and grunts!
We intend to try a pressure test first, though.
Nigel Wathen

 

[gtuson]

I had a leak from a new stainless tank last summer. Very unpleasant! It turned out to be a faulty weld, which I only diagnosed by taking the tank out. Not too difficult as i had put it in so knew how to remove. The original manufacturer repaired it for free. You may have no choice but removal if definitley not leaking from any fittings.

 

[NigelW]

Re: Fuel Tank Leaks-Results

Thanks for your ideas.
We ripped out the bulkhead, or, to be honest, we organised a yacht repair man to do it. (A question of time).
The tank is aluminium and had a small hole at the bottom. It was removed. All the laminated plywood was sarturated and will need replacing. What a mess.
The tank has been plugged and will go back in. This time we will arrange it so that there is an inspection hatch whic you can actually look through.

Hopefully all will be well, but we lost Easter on the water.
Fair winds and sunshine to you all.
Nigel W