Fuel tank leaking diesel.

[andyc]

Ally Fuel tank is buried deep in the bowels and it seems to be weeping diesel from the weld on one corner.

Without cutting up the boat,how the hell am I supposed to fix it?

HELP!

 

[highandry]

No experience with a fuel tank but I helped a mate who owned an old Air-Sea rescue boat which had a similar problem, but a hydraulic tank built into the bilge.

Are you sitting down? you're not going to like this...
IF you can get access to just the top of the tank....

Drain the tank completely. Using a good cold chisel cut the top out of the tank round the inside rim. (Not a grinder because of fuel residue and fumes in your case)
When you've got access to the tank, clear it out completely and when fume free grind off jagged top inside edge. Disconnect supply and air vent/fuel return pipes.

Line old tank with carpet tiles.(anti chafe) You might be lucky to get a ready made plastic tank to slide in, he wasn't, so he had one made to measure. Re-routed fuel lines.

A right performance, but not difficult really and a bombproof solution, no more leaks and the way that thing vibrated when he opened up both engines...things always leaked..

 

[andyc]

I have about 2" above the tank and it is tucked behind one engine so just cant get to it.It is 500litres so not small.To remove the tank is just out of the question without cutting it or the boat up.


Its a pinhole and boat is not worth spending £20k removing the bridge etc.

 

[Divemaster1]

No easy, long lasting fix I am afraid ...

http://www.ybw.com/forums/showthread.php?t=194575

 

[Spyro]

If it's leaking from a weld it probably is corroding from the inside out, it will get worse and might start elsewhere. A fix which will last a good few years is drain the tank to stop the weep dry the surrounding area outside, clean back to bare metal if it's painted and cover with a few layers of fibre matting and epoxy.

 

[highandry]

Ah! I was afraid that may be the case. I know a range of temporary repairs were tried but none lasted long, perhaps Spryo's might? I know little about epoxy mixtures etc:, but would it be worth considering draining the tank, washing it out and thoroughly drying the inside and then pouring in a thick suitable epoxy (or similar) mix? You might lose a gallon or two capacity but it may give you a 'False bottom' and cure the leak. If you could find a mix that didn't shrink away from the sides and would resist vibration, you might be lucky.

 

[andyc]

The tank is aluminium, the fuel is diesel and the boat is only 9 years old.I cant see corrosion being the issue.Its a manufacturing defect if anything.

What about filling with water so it wont explode and then a little bit of spot welding to fill the hole?I know they weld underwater on oilrigs so there must be a technique.

 

[highandry]

Not sure on that one, I'd be guessing or googling on that answer. Hopefully someone with knowledge will help you out with a reply.

 

[footsoldier]

My only experience with a leaking aluminium tank was with a motorcycle - also a pinhole in a bottom welded seam. (Theorised that stray currents from the in-tank electric pump had caused electrolytic action in the water - condensation - that had collected in the bottom).

I drained it dry and applied a patch of a two-stick resin, sold in motor spares shops specifically for fuel tank leaks. Still holding firm 5/6 years later. Worth a try?

 

[cimo]

If I could get one hand to it - I would give isopon a try.

 

[omega2]

tank leak

When ours went (stainless steel) we were able to get it out, what we found on the under side was at least 6 stress fractures, caused by the tank being in direct contact with inside of the glass fibre hull, no insulation whatsoever to absorb vibrations. After a false bottom had been welded on it went back sitting on a bed of conveyor belting. ope you are able to fix it by "filling" the hole but if vibration caused it do not hold your breath on it lasting.

 

[rivonia]

Ally Fuel tank is buried deep in the bowels and it seems to be weeping diesel from the weld on one corner.

Without cutting up the boat,how the hell am I supposed to fix it?

HELP!

Is the leak on the TOP or on the BOTTOM? If it is on the top do what I did on my previous boat. I got an aluminium self tapping screw and screwed it in to the pinhole then araldited over it. IT STOPPED the leak.

Peter

 

[Taurus66]

May i suggest an aircraft type long rangefuel bladder, if someone is flying a small plane over an ocean for delivery to a customer they often fit in a tough flexible fuel bladder inbetween the seats and run bypass fuel lines. Giving vastly extended ranges.. on a small plane we are talking 3-4000 miles extra range with a bladder tank.
If you like i can make some enquiries from a company i know makes 300 000 litre flexitanks for the agri industry.