Diesel tank - slow leak

[kipwrite]

Just completed a refit on a 52' 1988 sloop, replaced both fresh water tanks, one of which had a split at the seam, with new aluminum tanks (a complex and expensive project). Both diesel tanks passed a pressure test before we relaunched.

Sadly, now, after about 6 months, one of the fuel tanks appears to be seeping fuel, slowly, when topped up and on one tack. The tank tender fuel guage still works, haven't had an opportunity yet to conduct another pressure test. Most fittings, hoses, and hose connections appear sound, to the extent I can observe them.

Of course access is a particular problem - the tank is glassed in, with interior cabinetry blocking a good view from many angles. There is a tank access panel up top which provides a limited view, as internal baffles obstruct much of the view.

Anyone have any suggestions on how to find this leak and potentially repair it?

I don't have the heart to subject her to major surgery again unless aboslutely necessary, not to mention the costs of another huge tank project.

Thanks in advance for any suggestions...

[Chief Engineer]

Check connections and withe regard to the sending unit....if a new one was installed, the screws usuall have a small bit of sealant on them from the factory....and unless you know anything about pressure testing tanks, don't do it.

[Pblais]

Were the fuel tanks manufactured similar to the water tanks? If so it's hard to feel they would not suffer the same fate as the water tanks eventually. You would need to get a visual indication of where the leak was to think about how to fix it. It's more an issue of if it is a seam coming apart it's probably not going to stop. That could make for a real sea disaster story so the risk of it opening more is the worst case scenario.

To avoid the tank project part 2 you'll need to find the leak some how. One of those tiny surgical cameras would be ideal. Otherwise, I suppose you could start opening up the access and hope you find it cheap. Once you knew what type of leak it was you could decide how to treat it. Not knowing seems far worse. Perhaps draining the tank as much as possible and using a pressure source might identify the location easier so you might really see it leaking. It still leaves the case where there are two or more leaks.

I just fixed a minor leak from a bad fuel pump for the diesel stove and just that small amount of fuel was making the boat smell pretty bad.

[Boracay]

A small video camera sounds good (if expensive).

I have used a mirror and a torch to inspect spaces with restricted access.

It helps to be a contortionist.