Lining/coating inside of leaky aluminum gas tank

[jdlough]

My '85 Wahoo has a built-in, leaky aluminum gas tank. Removing it would involve way too much cutting and rebuilding the built in fiberglass bench than I want to deal with.

I can remove a wood plank over the gas tank, cut a 1' X 2' hole in the top of the aluminum tank, repair or reline the tank from the inside, rivet/screw and seal a new sheet aluminum tank top on to the tank. In theory.

I vaguely recall some tank liner stuff you can spray around inside the tank through the fuel sender hole, or 'paint' around the inside of the tank.

Anybody heard of or have experience with such a thing?

Another option is to cut out the tank in pieces and remove it through the top hole, and drop in an expensive custom-sized flexible tank bladder. For several hundred dollars.

I currently use a portable 6 gal tank instead of the leaky built in tank.

BTW, the tank didn't leak until I cleaned it with Star Brite/Star Tron Fuel Tank Cleaner.
http://www.starbrite.com/item/star-tron-tank-cleaner
Apparently the gunk in the tank was the only thing keeping it from leaking.


Here's a pic of the tank area (before I did some clean up and renovations).

 

[crabby captain john]

Re: Lining/coating inside of leaky aluminum gas tank

If it were a water tank I'd agree. A gas tank~~~ fuel would shortly eat everything I can think of you would line it with. I have not heard of that miracle spray that will hold up to gas.

 

[64osby]

Re: Lining/coating inside of leaky aluminum gas tank

Saw a product a while back, PUR 15 Fuel System Restoration . It restores old tanks. The tank would have to be pulled.

In terms of safety the tank should be pulled, repaired or replaced (IMO). Last thing you want is a leaking tank in a boat.

 

[robert graham]

Re: Lining/coating inside of leaky aluminum gas tank

Wonder if you could cut a hole in the top of the existing/leaking aluminum tank large enough to insert a new plastic fuel tank inside?....of course the new tank would have to be slightly smaller, giving up some capacity...Moeller makes tanks of all sizes and shapes, so maybe one would slide right in there?....regarding sealing your present tank, I just don't know....maybe after you cut your 1X2 ft. hole you can look/see down inside to locate the leak, then try to seal it?....last thing anyone needs is a leaking built-in gas tank...could turn your boat into a bomb!

 

[GA_Boater]

Re: Lining/coating inside of leaky aluminum gas tank

The leak is most like due to corrosion from the outside of the tank, so relining is going to be a leaky bandaid, if it works at all. There are linings that hold up to ethanol, but they aren't sprays and the tank has to be meticulously clean. The coating is applied by twisting and turning the tank in all directions, quite difficult to do in place.

If you can expose enough of the top of the tank, you might be able to cut the top off and fit another slightly smaller tank inside. Of course by that time you can yank the tank and repair it if possible or simply replace it.

You might find the reason for the corrosion is wet foam under the deck. Good luck.

Since you edited pics into the first post, what's so hard about taking off the top of the bench?

 

[jdlough]

Re: Lining/coating inside of leaky aluminum gas tank

what's so hard about taking off the top of the bench?

The tank within the bench is wider than the board on top of the bench. To remove the tank, I'd have to cut a lot of fiberglass, and rebuild.

I have too many projects to deal with that, for now. In my spare time, I'm still rebuilding my pier and yard from last year's Hurricane Sandy destruction.

I may just keep using the 6 gal portable tank for another season, then fix the boat right, if there's no such thing as a quick fix for a leaky aluminum tank.

 

[jdlough]

Re: Lining/coating inside of leaky aluminum gas tank

Saw a product a while back, PUR 15 Fuel System Restoration . It restores old tanks. The tank would have to be pulled.

FUEL TANK REPAIR KIT

This might work, if I cut a big top access hole and thoroughly clean the inside of the tank with their chemicals.

Thanks for the link. I will look into this.

 

[smokeonthewater]

Re: Lining/coating inside of leaky aluminum gas tank

looks like the key to fixing that one "right" it to separate the cap from the hull.... MIGHT not be that big of a job

 

[foodfisher]

Re: Lining/coating inside of leaky aluminum gas tank

looks like the key to fixing that one "right" it to separate the cap from the hull.... MIGHT not be that big of a job

Like this idea. It would expose other uglies also. Any job worth doing is worth doing right.

 

[crabby captain john]

Re: Lining/coating inside of leaky aluminum gas tank

Like this idea. It would expose other uglies also. Any job worth doing is worth doing right.

Om a boat that old anything could be found.... Hope all good stuff for the young man.

 

[Scott Danforth]

Re: Lining/coating inside of leaky aluminum gas tank

the POR15 product may work, however you need the tank out for that as you have to rotate the tank around every side to evenly distribute the sealant. at that point, I would drop a new tank in its place

 

[Home Cookin']

Re: Lining/coating inside of leaky aluminum gas tank

I vote replace the tank as the only solution. One hole indicates many more there or ready to spring loose unless you find a particular cause such as a screw hole.

Maybe you can fit a 12 gallon tank in the console? They make them for it; whalers have them. Also helps with the weight distribution; most tanks sit more to forward. Of course the lower the better.

Maybe you can get one that fits inside that bench seat? If the hull is solid (no bilge) you can get rid of some flotation in there.

I don't think you can "remove the cap" on a solid hull boat if that is what you have--whaler clone, right?

If my experience will help: I had a leaking 20 gallon tank in the floor of a 17" key west DC. Even though it had a floor panel, this was the first model year and the tank was a perfect rectangle (picture a brick) and could not be lifted out; later they put a slant at the front so you could slide it under the deck and drop it in.
to get the tank out they had to bust it up and cut it up, In addition to the design problem, the spray-in foam was like glue to it. (Hint: keep foam and parts spaced apart a bit). I reall they cut the floor out of the front anchor locker too for access; been a while since i looked at it and my dad had it done.
Then to put a new one in, we got the newer version with the slant so it could slide in.
So the planning of getting the new one in is just as important, maybe more, as getting the old one out.

 

[Chris1956]

Re: Lining/coating inside of leaky aluminum gas tank

That tank has had 50::1 gas/oil fuel in it? That would be real hard to clean sufficiently to epoxy the tank. Epoxy might (might) fix the leak, if the leak is on the bottom, and the metal can be made clean enough for it to stick, and the epoxy starts to leak and then cures.

Can you cut the part of the tank away, that is under the bench and then work a replacement tank into the opening?

 

[crabby captain john]

Re: Lining/coating inside of leaky aluminum gas tank

If you have to pull it to fix it, put a new one in. Fix this one and another hole will be trying to poke through. A new one means no more worries about the tank for another 20 years.

 

[thumpar]

Re: Lining/coating inside of leaky aluminum gas tank

The tank within the bench is wider than the board on top of the bench. To remove the tank, I'd have to cut a lot of fiberglass, and rebuild.

I have too many projects to deal with that, for now. In my spare time, I'm still rebuilding my pier and yard from last year's Hurricane Sandy destruction.

I may just keep using the 6 gal portable tank for another season, then fix the boat right, if there's no such thing as a quick fix for a leaky aluminum tank.

View attachment 219744 View attachment 219745

If the top of the bench comes off you could just cut up the existing tank to remove it and install a smaller one that doesn't require you to cut up the boat.

 

[jdlough]

Re: Lining/coating inside of leaky aluminum gas tank

Here's a cut away of the boat. I'm not sure if the foam is bonded to the deck, the hull, or both. I'll have to do some searching to see if anyone has removed the cap off a Wahoo.



If I can't remove the cap, I can remove the plank on the bench, cut through the bench top, cut up and remove the old tank, and install a flexible tank in its place. Maybe from some company like this one:
Marine Fuel Bladders and Auxiliary Fuel Tanks

Or install a smaller capacity regular tank that could fit through the new hole.

Here's the boat with the bench plank removed:

 

[smokeonthewater]

Re: Lining/coating inside of leaky aluminum gas tank

the first pic in your last post APPEARS to show an air gap between upper and lower foam... IF that is so then it SHOULD be possible to pull the cap BUT honestly looking at it again, the plan of cutting an access in the top of the bench and the top of the existing tank installing a flexible bladder inside the existing tank might be a decent option... gonna be REAL hard work tho to cut away the top of the tank all the way to the fuel inlet area without using anything electric or otherwise able to make sparks.

 

[Home Cookin']

Re: Lining/coating inside of leaky aluminum gas tank

Pulling the cap off is not an option in my uninformed opinion. If you want to explore it further, consult the whaler restoration forums (continuouswave.com is one). even if it is possible, reworking the bench is a lot easier.

Why not remove the bench box completely, replace the seat with a plank seat, put the tank under it? Nothing personal but given the state of the boat, looking pretty is not one of its life goals.

 

[jdlough]

Re: Lining/coating inside of leaky aluminum gas tank

Why not remove the bench box completely, replace the seat with a plank seat, put the tank under it? Nothing personal but given the state of the boat, looking pretty is not one of its life goals.

Hah! Those pics are from when I bought the boat for cheap a few years ago. After power washing, replacing the planks with Ipe wood, replacing seats, LED nav lights, and other futzing, it looks pretty good now.

Here's partway through the restoration:


I don't want to remove the bench completely, since it's formed as part of the self-bailing deck.

 

[Chris1956]

Re: Lining/coating inside of leaky aluminum gas tank

You can cut away the fiberglass of the bench, rip out the tank, install some sort of new tank and then repair the bench. With planks over the repaired area, no one can see the repair.

Also, with some white resin colorant, and some extra coats of resin to fill the glass mesh completely, it will not look too bad. You can sand it down flat with course paper and then wet sand it to 400+ grit.