Leaky Diesel Fuel Tank - Fix or Replace?

[Carl-T705]

Originally Posted by Lepke

Whether you fix your current tank or have another built, apply a diesel tank coating to the inside and the tank will outlast the boat.

. What is a diesel tank coating????

[kmacdonald]

Since you say it's hard to get out, replace it instead of repair. Aluminum is a better choice if a stock poly tank won't fit.

[Stu Jackson]

It is truly heartening to hear of successful repair stories.


Anecdotally, however, over the past 20 years that I've been reading boating forums, the consensus has been: if in doubt, rip it out, and replace.


Of course, if it is difficult or impossible to replace, knowing "cures" is always helpful. Thanks for those.

[r spicer]

Originally Posted by and4ew

My planned five-day coastal cruise was cut short when I found that diesel was leaking into my bilge. I checked the hoses and fittings and didn't find any diesel drips, and also the bilge slowly fills even when the engine is not running, so I surmised that the tank itself is leaking.

The tank sits in the bilge, a little off the bottom. It's mounted with fibreglass shims. It's not the original tank but was "custom made"
I'm guessing that the bottom, sitting so close to the bilge, has corroded. I haven't pulled it out yet as it's more than I could do by myself.

My options are to pull it out, find the leak, and weld. Alternatively, I could just replace it with something like a Moeller Marine fuel tank which are not metal. So my first question is: should I fix or replace?


Second question: the Moellers (and others) I've seen don't seem to have a return for diesel. Would I just add another spigot for that? If so, should it have a hose that goes down into the tank (like the feed-side does)?


Third question: my current tank is 70 litres. That seems like a lot for coastal cruising. I consume 1 litre per hour @ 5 kt and don't have to charge my batteries often. I feel like 30-40 litres would be fine for coastal cruising. Thoughts on this?

a third option is to chemically seal the tank. It requires cutting a large hole in the tank, throughly cleaning, then acid etching, then applying sealant..
Chemical cost would be about $100.
Then, obviously resealing access hole.
Your arm & shoulder gets a real workout, but way less that ripping out the entire tank, or giving your wallet a real workout for a much smaller tank.Good luck<.>

[Mjames]

Might suggest you make sure the vent hose(s) isn't the culprit. If I fill my tank to the point where fuel sits in the vent hose, I get some leakage. my understanding is these hoses can go before welds in the tank itself. Might save you from a much bigger project...