Repair options for rust holes in bottom of fuel tank

[timsch]

I've got rust holes in the bottom of a 40 year old Kubota tank. The holes shown in the picture are from after I cleaned the inside with E85, flushed it out, and dumped in a bunch of pea gravel to shake around in soap water to free up loose gunk on the inside, and then me probing with a pick and small screwdriver to expose any other weak metal. All hole that I've found are on the bottom.

Repair options I've seen mentioned are JB Weld Tank Repair, other epoxy repairs, & welding.

The JB Weld reviews have a number of people claiming it was only a temporary fix. Similar with other expoxies.

I have welding options (MIG & TIG); my skills are decent, but still amateur level. What I would like to do is cut a patch for each hole/area, bolt it in place, and then weld it all up, but I don't have an access hole large enough for my hand to work from the other side. I'd think if I tried to weld a patch from the outside, I'd end up burning through the thin metal.

The safest bet for me probably is to try the JB Tank repair, and if that fails, revisit this again. I'd sure like to get it right the 1st time though.

What would you do?

 

[Steve@Advance]

Only if a new tank is unavailable should that be repaired.

If I were repairing that, I would cut the entire section out, right around the radius of where the bottom
curves in. Chances ae that entire section is rusted very thin in other places too.

Then make a cardboard pattern, cut out a piece of sheet metal, and carefully form it to fit back in, weld
it up, leak test it with water. Keep welding until there are no leaks.

 

[rusty6]

I've been running a couple of International trucks with JB welded holes in the gas tanks for years. Holes might have been smaller than yours. Seems to me I turned in a sheet metal screw and then plastered it and the area around it with jb weld. It worked for me.

 

[BarnyardEngineering]

I would have to question the claims of "temporary fix." IF you don't prep the surface correctly, the JB weld won't stick. Then as someone else mentioned, it's likely the metal around the holes is also thin and ready to give way at any moment, so is the repair leaking or is it just leaking in a new spot?

 

[timsch]

Parts for this L275 are hard to come by. There's a used one on Ebay for ~$400, but may not be better than mine.

I agree that the entire bottom would be thinner, and that it'd be a good idea to cut it out entirely.


rusty6, was that regular JB Weld or the tank repair version?


I did do a bit of probing looking for more weak metal, and exposed what I found. I could have missed some areas, though.

This post was edited by timsch on 12/27/2022 at 10:56 am.

 

[cool hand]

I had a similar looking fuel tank on my IH 884 about 8 - 10 years ago. I cleaned and sand-blasted the area, then covered the area with fiberglass fabric and liquid resin. So far not a drop of fuel leakage!

 

[rusty6]

(quoted from post at 11:53:57 12/27/22)


rusty6, was that regular JB Weld or the tank repair version?


I did do a bit of probing looking for more weak metal, and exposed what I found. I could have missed some areas, though.

Its probably 20 years ago but pretty sure all i have ever used is the everyday ordinary version of jbweld. Just cleaned up the area right to bare metal and then applied the screw and patch. It was cold weather so left a trouble light hanging close to it for quite some time to give it sufficient drying time. Tank has not leaked since and the truck is used every year.

 

[timsch]

Glad to hear. Fiberglass would be the easiest for the curved areas. It must be able to handle diesel better than gasoline.

 

[Jim in LA]

Did this on recommendation after commercial tank patch failed immediately. Tank:8N gas tank.
Patch piece of cotton pillow case, sheet or flour sack. Mix two packages of JB Weld, thin with
lacquer thinner and liberally apply to affected area and saturate the patch piece with it. Let cure
for 12-24 hours. Ours has lasted over twenty years. Surface prep very important of course.
(clean and scour)

 

[timsch]

(quoted from post at 12:40:30 12/27/22) Did this on recommendation after commercial tank patch failed immediately. Tank:8N gas tank.
Patch piece of cotton pillow case, sheet or flour sack. Mix two packages of JB Weld, thin with
lacquer thinner and liberally apply to affected area and saturate the patch piece with it. Let cure
for 12-24 hours. Ours has lasted over twenty years. Surface prep very important of course.
(clean and scour)

Was the laquer thinner used to allow the JB Weld to penetrate into the sheet better? About how much thinner was it?

 

[kencombs]

I would cut and braze patches in place. Much easier (for me
anyway) to get a leak free seam with braze. Or silver solder,
either is a good option.



Ive wanted to try MIG brazing. That would be a good project
for that.

 

[Patsdeere]

What about jb welding it to seal it then
coating the inside. Then the jb is simply
filling hole to keep tank liner in not
holding back chemical.

 

[BarnyardEngineering]

(quoted from post at 12:21:27 12/27/22) Its probably 20 years ago but pretty sure all i have ever used is the everyday ordinary version of jbweld. Just cleaned up the area right to bare metal and then applied the screw and patch. It was cold weather so left a trouble light hanging close to it for quite some time to give it sufficient drying time. Tank has not leaked since and the truck is used every year.

I would be truly surprised if there is any difference between the plain jane JB weld and the "special" tank repair formula. It's just marketing.

Have you ever noticed that there is about a dozen different "formulas" for a product called "Amazing GOOP" in the adhesive aisle? Marine GOOP. Automotive GOOP. Plumbing GOOP. Household GOOP. Craft GOOP. Trim repair GOOP. All the same GOOP.

 

[timsch]

(quoted from post at 12:49:10 12/27/22) I would cut and braze patches in place. Much easier (for me
anyway) to get a leak free seam with braze. Or silver solder,
either is a good option.



Ive wanted to try MIG brazing. That would be a good project
for that.

I can weld, and I can solder, but for whatever reason, I've had no success in brazing. I always seem to wind up with cooked flux and brazing material that will not flow. I've heard of TIG brazing, but never MIG brazing.

 

[Crazy Horse]

I had a good laugh with your reply Barney. Or as someone might say,'Same Old _ _ _ _'

 

[4020man]

I have used the fiberglass with body putty containing fiberglass strains in it with good results on both gas and diesel fuel tanks fo years and have good luck. Just
have a clean surface to start with.

 

[RCP]

I have also used fiberglass with good success on rusty car gasoline tanks. You have to get the surface clean, be generous with the matt and let it dry for 24 hours in a warm environment before filling the tank.

 

[timsch]

Thanks to everyone for their input.

I'll plan on doing a mat covering, with either fiberglass or JB weld & cloth. If that fails, I'll cut the bottom off and weld a new bottom onto it. If it comes to that, hopefully the additional welding experience will come in handy.

 

[EX Deere Farmer]

Look up a product call Seal All it will be in a yellow/red tube. It is petroleum resistant. Sand the paint off around the holes until your down to bare metal. Put a bead of the Seal All
around each hole. Press screen wire down into the Seal All. Let that dry. They just add layer of the seal all over/into the screen until you have it thick as the tank was to start with.
Paint to the color you want the tank when done. I have Gas tanks on restored cars that have repair like this, that are over 40 years old and still holding well.

 

[37 chief]

If it were mine I would forget about fiber glass unless you use special resin. I tried fiber glass on my Jd diesel tank. After a while it started
leaking again. Jb weld will work. Get the metal shinny clean. Then would put a blob of Jb on a round metal disk, and push it on the hole. Jb Weld makes
a fast setting also. Stan

 

[rusty6]

Back about 30 years ago my dad had a huge hole ripped in the gas tank of the 69 Ford Falcon after a chunk of scrap metal sprung up off the highway and blew it open. Nobody around here would risk welding a gas tank but a very good welding and repair shop took on the task of soldering (no flame) a big patch of sheet metal over the hole. It held for years and never leaked. I would not try welding a gas tank.

 

[stevieb49829]

I'm with Steve@A on this one. If you cut the holey bottom out, you have access to inspect the rest of the bottom, with a light and mirror, or bore scope. Then make your patch fit really well, spot MIG it all the way around, and keep welding and grinding until you get no leakage. Good MIG practice. I've made a plug or diaphragm over the cap for the filler hole, and a tire stem adapter for the outlet. Then you can stick about 20 lbs of air in it and check with soapy water. Easier than drying it out enough to keep welding up the pinholes. If you have to fight too long with the MIG, go back over it with the TIG and make it look pretty. Good practice there, too. steve

 

[Bob Harvey]

Seal All, the best ever. I had a '38 Pontiac sedan that the bottom of the tank kept developing leaks. My dear old dad came up with Seal All, sheet metal screws and leather (cut from an old belt) washers. When I sold the unit, it had at least 30 of these repairs, and yes I did tell and show the purchaser. He called me a couple of months later to tell will he was still using the method !! If you don't believe, I will try and find his phone #. ;^)

 

[stevieb49829]

Your hardest part of welding it up will be either working around the outlet tube, or replacing it when you make a patch. It's probably brazed in with either brass, or copper brazed. You could melt it out of your part, and braze, or silver solder it back into your patch, before you weld the patch in. Look at some Utube videos on MIG welding sheet metal. Most folks spot/skip/spot until the whole seam is spot welded together. Lots of body work done that way. steve

 

[Stephen Newell]

I wouldn't use any kind of epoxy. It will hold for a little while and then leak. I would cut small pieces of sheet metal and braze them over the larger holes. Then use a fuel tank liner
to seal the pin holes and prevent further rust.

 

[wh]

Not sure i would go to 20 lbs of air. 4 to 5 lbs will find the leaks and wont launch it into orbit like 20 lbs will.

 

[el6147]

lots of suggestions here.

I am going to answer this from experience , like rusty6 suggested solder with a patch .

make sure the area is bare bright clean , prepare a metal patch that is bare bright clean , tin the tank
and metal patches and solder .

I have repaired diesel tanks and gas tanks in this fashion.

 

[hd6gtom]

NAPA has a kit made just for this purpose. I used it many years ago and its still holding even with the constant use of ethanol gas.

 

[Stan Coryell]

I've done the same without issues. 200 watt iron comes in handy.

 

[timsch]

(quoted from post at 19:02:19 12/27/22) I've done the same without issues. 200 watt iron comes in handy.

I do have lots of soldering experience, although mainly with wiring, so this would be different. I did just get a 200W soldering gun for Christmas. Never used one of those before.

Looks like I need to get some scrap sheet metal to practice on.

 

[T.R.K.]

As far as JB weld repairs go, I bought 69 GMC truck in '1993. I finally got in back on the road in 2003. It was sometime after 2008 that the
in-cab fuel tank began to leak. On the bottom where it could not be seen, there was a JB weld patch. I think the JB weld patch lasted about
15 years.

 

[teachingscience]

I had a massey gas tank with a hole large enough to stick two fingers through and many smaller holes. I brazed a patch over the large hole
and used a product called red-kote to coat the entire tank on the inside. That was around 12 years ago and its still going strong. I prefer
this to just patching because if its rusted through in that many places, its just a matter of time before you'll get new holes. You've
already performed the the cleaning routine that I used so you should be ready to run with this method and once its coated, you wont have any
new holes.

 

[flying belgian]

When I had my metal fab. shop people would bring gas tanks in all the time.,,Can you patch these holes? My answer was always the same,,NO. I can however repair your tank.
Cut the whole bottom out and weld in new.

 

[caterpillar guy]

Cut the deeper portion off the tank. Then fit tightly and solder part of it or over lap it then rivet it to the old tank. Then once fastened to the old tank in place just braze it on around the edges. I've not had good luck with sealing a welded tank that thing. Heavy fuel supply tanks like the ones used for storage I have welded with good results. Thin fuel tanks like yours the brazing worked better since it could flow into the seem to seal and fasten both together Sort of like soldering. I don't believe a 200watt soldering gun is going to give a good sweat joint > Maybe a cold joint but not a good flow sweat joint like you need here. A torch with small tip would work. Problem with torches is keeping the heat down so the tank doesn't warp or distort away from the patch or vise versa.

 

[timsch]

(quoted from post at 19:34:00 12/27/22) I had a massey gas tank with a hole large enough to stick two fingers through and many smaller holes. I brazed a patch over the large hole
and used a product called red-kote to coat the entire tank on the inside. That was around 12 years ago and its still going strong. I prefer
this to just patching because if its rusted through in that many places, its just a matter of time before you'll get new holes. You've
already performed the the cleaning routine that I used so you should be ready to run with this method and once its coated, you wont have any
new holes.

My understanding from researching using POR-15 is that diesel leaves a residue that prevents using a sealer on the inside of the tank.

 

[gene bender]

sand it down to bare metal then fiberglass resin and cloth never leak
again couple layers of the cloth letting each cure before next layer. JB
WELD can break

 

[timsch]

For my repair, I just used my MIG welder to fill the holes. Most of the smaller holes were easy without burning through, but some of the other larger ones I laid a bead around the hole and build up filler on the ID until the hole was gone. This was not 100% effective in that I can see some pinholes with the tank held up to the sunlight, but these are so small that I feel that filling them with SEAL ALL should be effective. Once I do that, I plan on putting a layer of JB Weld with the cloth reinforcement over the whole bottom area as mentioned on the 1st page by Jim in LA.

It's a bit convoluted, and I'm sure that it could have been done better in a single step by a number of you fine people, but it seemed the best option for me and my skills. I'd have cut the bottom off if it weren't for the fuel outlet tube on the bottom that I wasn't 100% sure of being able to reattach it well enough.

I figure that this should work, probably for quite a while, and if/when it fails, I'll cut the bottom off and weld or braze a new one on as suggested. This gave me more experience with the MIG welder and gas tanks that will come in handy when that time comes.

Thanks again to everyone with their suggestions.



Edit: One question about the laquer thinner to thin JB Weld per Jim's method - are Acetone, Naptha, Xylene or Mineral Spirits acceptable substitutes? I have those onhand.

This post was edited by timsch on 12/30/2022 at 09:18 am.