Leaking diesel fuel tanks

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Tex Stephenson

Member
Joined
Jan 14, 2016
Messages
13
Location
USA
Vessel Name
HEAVEN SENT
Vessel Make
1992 Grand Banks 46 Classic
I have a 1992 Grand Banks 46 classic with a leaking fuel tank. I would be grateful for some advice on how to correct the problem. I believe the tanks are mild steel. Please help.
 
Could be a simple pin hole repair leaky fittings or require new tanks ??? Any other information where the leaks are or photos ?
 
gaston said:
Could be a simple pin hole repair leaky fittings or require new tanks ??? Any other information where the leaks are or photos ?
Click to expand...
Port tank, forward outside corner. I'm 6ft 3in and 72 years old. I just don't bend the way I used to. Using a mirror I can see some rust on the top of the tank near the fill hole but the tank is half empty and so the only other place I see deterioration is the front corner I mentioned.
 
I believe you should have at least one access plate on that tank. If not you need to add one so either way you can empty it then open it and look inside.

You also should look into renting, borrowing or buying a fiber optic camera so you can see the potential leak site better.
 
Leaking fuel tanks

I will have to pump the remaining fuel into the other tank. Then I'll open it.
In the meantime, I'm open for suggestions
Thank you
 
I'm in the process of replacing my original fuel tanks on our 1986 GB 42. I considered attempting to repair/seal my tanks and hope for a fix. However, after discussing this with some folks on the GB Owners forum and friends in the industry in the San Francisco Bay Area, I elected to replace the tanks rather than throw good money at the high risk of not being successful.

I'm having American Tanks out of San Diego cut out the old tanks and replace with aluminum tanks of near equal volume. I'll post the results when the job is complete.

Feel free to send me a private message and I can put you in touch with my contact at American Tank, should you decide to take that route.
 
Giggitoni said:
I'm having American Tanks out of San Diego cut out the old tanks and replace with aluminum tanks of near equal volume. I'll post the results when the job is complete.
Click to expand...
How many tanks are you putting back in, Ray and will you be able(or willing) to do a show and tell along the way?
 
We plan to install three horizontal tanks on each side. The reason for three tanks is because we don't have the room to fit one single tank without removing the old tanks through the bottom of the boat. A solution looking for a problem!

The tanks will be plumbed together on each side to form essentially one tank. The old tanks are 300 gallons each for a total of 600 gallons. The new tanks will have a total volume of about 520 gallons.

I'll document the tear out and installation when we start in about two weeks.
 
Check out a product called Por15. After "priming" the rust with the liquid product, apply a layer of the paste and you can forget your leak. You will have to pump the tank (maybe one into the other), tip the boat till the remaining fuel is away from the leak area, wash with the Por cleaner, dry, make sure the weep has stopped, then apply the stuff. A starter kit and a tube of paste should do both tanks unless you are going to coat the entire tank. Hire a small helper.
 
Giggitoni said:
We plan to install three horizontal tanks on each side. The reason for three tanks is because we don't have the room to fit one single tank without removing the old tanks through the bottom of the boat. A solution looking for a problem!

The tanks will be plumbed together on each side to form essentially one tank. The old tanks are 300 gallons each for a total of 600 gallons. The new tanks will have a total volume of about 520 gallons.

I'll document the tear out and installation when we start in about two weeks.
Click to expand...
Thanks Ray, I don't envy the work but it does seem like you have a good solid plan and I look forward to seeing it unfold.
Good luck.
 
Capt.Bill11 said:
You also should look into renting, borrowing or buying a fiber optic camera so you can see the potential leak site better.
Click to expand...

Check out Amazon for their boroscope or endoscope which is simply a tiny camera in a brass housing at the end of a long USB cable. Plug the USB cable into your laptop and fish the camera end wherever you want to see. The camera end has a few LED's to light up the area around the camera in darkness.

Range in cost from $15-$30 for up to 20' length. Good to go exploring all over a boat. They are waterproof so you can tape it to a boathook and check out your prop / rudder, and even bilge areas.

Fiber optic cameras are far more expensive due to the fiber bundle accuracy. Also, they are length restricted since you get loss by the foot.

Stu
 
"The new tanks will have a total volume of about 520 gallons."

For someonr that winters aboard in a cold area thats a great number.

But for coastal cruising it seems like a lot to attempt to keep clean.
 
If you are too tall or too old to inspect the tank yourself, hire someone to do it for you.


My thought is that if the tank is rusted to the point where it's leaking, it's probably about to leak somewhere else. The "right" way to fix this is to replace the tank. Anything else is temporary at best.
 
Por15 is a good product for arresting rust formation on the surface of fuel tanks and other equipment. It is not intended, nor will it cure, an established leak; pinhole or otherwise.
 
Giggitoni said:
Por15 is a good product for arresting rust formation on the surface of fuel tanks and other equipment. It is not intended, nor will it cure, an established leak; pinhole or otherwise.
Click to expand...

I beg to differ. Por 15 will not only bond to and seal existing rust to prevent it from continuing but the thick paste will replace the metal that is already gone. I have helped two friends repair their steel tanks with the stuff and one has lasted 9 years. It will cure an established leak but not while it is leaking. That is why you must tip the boat, wash, & dry the area; it can't be weeping while you fix it. Of course cutting out the tanks and replacing with new is the best way if you have the time & $$$ and if the boat is worth it.
 
:thumb: I'm glad it has worked for your friends. Really, I am. I've never heard that using rust arrestor or any type of glue on an active leak has worked.

In my case, the leak is in the bottom of the tank blocked by baffles. When the tanks are full, about two pounds per square inch of hydrostatic head will overcome any rust stopper or glue. It's like painting the side of your house and expecting to cure the dry rot problem.

I still think, in the majority of leaking fuel tank scenarios, the replacement of 30 year-old leaking tanks (in my case) is the best solution. Do it now or do it later after one gets the middle-of-the-night phone call from the Coast Guard...!
 
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Giggitoni
Thank you for your response. I just joined this trawler forum and do not know how to send a private message. Not very computer literate.
What engines do you have? I think the type of engines will dictate the size of the replacement tanks. Also the size a placement of the generator. I am leaning towards a quick fix until I can do the job properly. We live aboard and timing is crucial. If anyone knows of any other products to fix the tank from the inside, I would be grateful for your comments.
 
Tex,

We have Cat 3208 naturals. I have to remove the exhaust components from the rear of the engines. Our Onan 8kw will have to be removed from its mounts and shoved to the side for each tank(s) installation.

Our original idea was to replace the original tanks with two replacement tanks. However, we are limited to 19" door width into the saloon from the outside. Hence, three tanks to come close to our original 600 gallon tankage.

I urge you to join the Grand Banks Owners forum, Grand Banks Owner's Resources. The folks there have superior experience with our GBs. The members just might have some good experience with Por15 or other solutions to a leaky fuel tank. Good luck!
 
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Had to replace my tanks on 45 Jefferson 8 years ago. Last week while doing checks found another leak at a weld at the vertical plate to the bottom plate. Will be going back to Lauderdale for repair . Looks like weld was bad and is weeping but still will have to remove engine and turn or remove tank. Welder said could be bad weld or crack in weld. Removed fuel /degassed tank and will see what welder wants to do tank in boat or outside. BOATS don't you love them ????
 
What material are your tanks? Aluminum, steel, stainless steel?
 
Giggitoni
Forgive my use of your name this way but as I said I don't do computers well. I realize there are differences between the two boats but I think you could remove your front windshield and get two tanks per side.. My windshield comes off by disconnecting the locking hardware, raising it to the level of the horn and then sliding it sideways. The tanks are about 31 inches wide and my opening 38 inches wide. I brought in a new refrigerator on a skid that way and it works great. I would love to talk to you. Is there anyway you could privately give me a phone number to call you with?
 
Private Message (PM) sent.

I was prepared to remove the front windshield, but the measurements for the horizontal tanks didn't work out. I also considered taking a larger tank in through the companion way into the aft cabin but didn't have enough room. Your GB46 may have larger access points than my smaller 42'.
 
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Rusty steel tanks.... no quick fix. Meditate and deal with it.

Then..... search the forums and learn that you will have to cut the boat or the tanks. IE, tanks don't fit through the door anymore, 'cause they put them in before the deck went on. So.... you either cut a large hole in the boat or cut up the tank and get it out in pieces. Trust me, the latter is preferred. Now, you say you're in your 70's..... not sure how much piss and vinegar you got left (not being flippant, sniffing 60 myself and I know where I'm heading) so the other option is to pay.... pay someone to crouch in there and cut the old sucker up.

Then, as a similar sized tank is not going to fit IN just as the old one didn't fit OUT so you'll have to design and have fabricated new multiple tanks (aluminum is your best bet) to fit through the door and have a place to sit...... Or pay someone big $$ to make the problem go away.

That's it in a nutshell. YMMV, but it ain't gonna be an "easy fix".

My $0.03
 
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Giggitoni said:
We plan to install three horizontal tanks on each side. The reason for three tanks is because we don't have the room to fit one single tank without removing the old tanks through the bottom of the boat. A solution looking for a problem!

The tanks will be plumbed together on each side to form essentially one tank. The old tanks are 300 gallons each for a total of 600 gallons. The new tanks will have a total volume of about 520 gallons.

I'll document the tear out and installation when we start in about two weeks.
Click to expand...

You may be jumping into deeper **** than you're already in by stacking the new tanks. If access is a big problem with one, it will be triply hard with three.
I would encourage you to locate the source of the water before installing new tanks, and taking appropriate steps to stop the ingress, whether it is dirty fuel at the source, leaking deck fill, improper venting, condensation, or what else.
 
Giggitoni said:
We plan to install three horizontal tanks on each side.
Click to expand...

This is somewhat similar to what the previous owner did with our '73 GB36 in Alameda the year before we bought it. The boat's original three, 150-gallon iron tanks (one on each side, one across the back of the engine room) were removed (I assume cut up in place as the engines were never moved) and replaced with four 85-gallon saddle tanks, two side-by-side on each side of the engine room, and a 60 gallon day tank on the centerline of the boat in the bilge under the engine room floorplates. Total fuel capacity was reduced from 450 gallons to 400 gallons which is great because this reduces the time fuel sits on the boat.

I have no idea who designed the replacement system but it's terrific because everything works via gravity out of the lowest point in each tank. The contents of the four saddle tanks are transferred independently to the day tank via gravity and manual valves, and the day tank feeds from its lowest point to the line to the lift pump on each engine. So no pickup tubes in the system at all and when a tank is empty, it is totally empty.

Fuel can be moved between tanks via a transfer pump and each engine can draw fuel from the day tank (normal) or either of the two saddle tanks on the engine's side of the boat via manual valves. The fuel return from each engine can be valved to the day tank (normal) or the forward saddle tank on the engine's side of the boat. The transfer pump can also be valved to pump the contents of any tank off the boat via a hose connection.

Very simple, very foolproof system.
 
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