pin hole in my inox diesel tank

[rubino]

Pin hole in the bottom side welding of my boat diesel inox tank.The leaking is about 100 grams /week.Very difficult job to remove the tank. The tank has not inspection port and it is impossible emptying the tank 100% out and clean the bottom.
It is impossible to reach the tank from above :it is located under the cockpit sole and the steering pedestal .Need suggestion to carry on at least for the summer.
Thank you

[skipmac]

Hi Rubino,

First, to make sure I understand, when you say the leak is on the bottom side welding, do you mean on the bottom of the tank but on the side where the bottom and side join together?

I know of no good way to fix this without draining the fuel at least below the level of the leak. Maybe someone else knows of something but any sealer or epoxy or any similar I know of will require the area where the sealer is applied to be clean and free of oil, gas, fuel, etc.

Are you able to reach the location of the pinhole? If you can drain the fuel and clean the area of all fuel residue you might be able to use a good epoxy like MarineTex or JB Weld, apply to the outside of the tank and use tools, small picks, pressure or whatever to force the epoxy into the hole. Maybe you can stop the leak this way.

Since there is no inspection plate on the tank can you remove a fitting like a fuel gauge sender or a fuel line connection to insert a small hose into the tank and suck the fuel out into a jug?

At some point you know you will have to remove the tank.

[skipmac]

By the way, I went through this on my boat. Fortunately the tanks were easy to remove. When I pulled the tank and looked carefully I saw several leaks. I took the tank to a welder, cut the bottom off the tank and found extensive corrosion and many, many places where the metal was almost completely eaten away.

The boat and tank was 30 years old and the previous owner had never cleaned the tanks. Over time a little moisture formed and in that water significant biocontamination formed that ate away the bottom of the tank.

If yours is an older boat and at some time sat with old fuel in the tanks you might have the same problem.

[DeepFrz]

I doubt that things are impossible to do. Difficult yes, but not impossible. I'm afraid you are going to have to do a difficult job.

[Captndave1]

I would empty the tank and clean it removing all traces of diesel and buy some aviation fuel cell sealer to coat the entire inside of the tank. You may have to install an access to do this, but it is a permanent solution to leaking tanks. I did this on a previous boat, and never had any more leaks.

[cal20dennis]

A possible solution to a pinhole leak....(BEWARE that the tank is ready to rust to death, and THIS is just the first hole!)
Drill a hole through the pinhole large enough for a #8 sheetmetal, self-tapping screw.
Screw through a piece of rubber then into the pinhole for a seal.
Good luck.

[basenay]

The more specific information you post the more likely you will get the best information.
1. Boat make, model & year?
2. Tank capacity?
3. Are you looking for temporary fix to get through summer or permanent?
4. 100 grams diesel ? 85 milliliters?

If temp fix can just live with it, frequent diesel absorbing material changes and keep tank almost empty so less pressure, if gets worse less mess to deal with & less fuel to empty when ready for permanent fix. Would give external epoxies or Stay Afloat or something similar that doesn't react with diesel a try.

To make decision on permanent solution need tank empty then cut sufficient size inspection port to determine condition of rest of tank. Good welder can fix with a "scab" or such for not a lot of boat bucks if tank & access is ready for them and rest of tank looks good from inside. If you are handy can make inspection port, gasket & tap bolt into tank yourself.
Maybe borrow or buy cheapo flexible scope which attaches to smartphone to aide you.

Bruce Senay
s/v Dreamcatcher IP45-03
Lying Neuvo Vallarta, Mexico

[GrowleyMonster]

If you have one leak now, probably in very short order you will have several. It usually works that way. If you can get to the hole with a drill you might drill it out and plug it with a self tapping screw for now. Don't use too big a screw or you could split the seam and have an even bigger problem. A pop rivet might work.

You might also consider a portable tank for now. I guess you would have to just wing it on the return line.

At season end you should plan on pulling that fuel tank. It usually isn't easy. I had to pull my engine in order to pull the leaky fuel tank. Since I had the engine out anyway, I decided to repower with electric. Anyway it seems nobody ever makes provision for eventual fuel tank removal.

You could try something like this, if you are willing to cut an access hole. Auto Body Toolmart - POR-15 Fuel Tank Sealer

I am afraid any in-boat repair is probably going to be only a temporary fix. The tank will have to come out. That's my opinion, anyway.

[model 10]

You are going to need to empty the tank. Somehow you need to pump out all the fuel. After that, start pouring in Acetone untill it comes out the leak clean. You will need to use several gal and pump out most of that also. Then pour in about a gal of epoxy. It too should start leaking out the hole but then cure. This will probably ruin the tank for future welding though.

[s/v michaela]

Belzona will seal and cure over mineral oil or water. Watch a few belzona YouTube videos on this amazing stuff. Contact your local belzona rep...

[mikecambrai]

There are quite a few rapid epoxy resins out there. I have used one called Leak Fix which may be only available in Europe, but there are others which will be dry in 5 minutes and completely cured within the hour. I have sealed up tanks where the diesel was seeping out. Just clean with a degreaser then immediately apply the epoxy or the epoxy putty and start sailing again!

[Cadence]

Originally Posted by Guy

You are going to need to empty the tank. Somehow you need to pump out all the fuel. After that, start pouring in Acetone untill it comes out the leak clean. You will need to use several gal and pump out most of that also. Then pour in about a gal of epoxy. It too should start leaking out the hole but then cure. This will probably ruin the tank for future welding though.

As crazy as that sounds it may work and also stop or delay the future holes which seem likely.

[foufou]

It is quite possible to put an inspection port in a tank if you have access to the top. I recently took a 5" hole saw to the top of my diesel tank. Battery drill and sharp hole saw. Took less than 5 minutes. Make a cover 2" larger diameter, drill ten screw holes and make a gasket. The inspection port might allow a repair from inside

[skipmac]

Here's a link to a thread I started on this same issue. Includes some photos of the inside of my tank. The photos are closeups of small areas but the corrosion covered all the sump area of the tank, maybe 40 cm X 20 cm.

http://www.cruisersforum.com/forums/...ank-99398.html

Unless your leak is just a bad weld spot on the seam you could have similar issues.

On the other hand, I had a SS (inox) water tank in a previous boat that started leaking from a seam. In that case the leak was not corrosion but I think the water sloshing in the tank caused flexing in the sides which work hardened and eventually split along the seam.

To repair that tank (which would have required pulling the deck off the boat to remove) I cut a large hole about 1 meter square in the top of the tank and paid a welder a nice bonus to hang head down into the tank and weld the seam from the inside.

[Delancey]

Had a pinhole leak in my aluminum tank, pulled it, installed inspection ports, cleaned it up, had a friend weld it up. Lasted a year or so before other leaks showed up.

Now I have a new poly tank and no more worries.

Popping a screw in the pinhole as suggested above is a good fix to get you through a season but as DeppFrz suggests, sooner or later you have a difficult job ahead of you....