OT: Proper method to repair (weld) leaking fuel tank?

[Wayne02]

Have a leaking fuel (diesel) tank on a JD450 crawler/dozer. Has been sitting for years, tank is empty (all leaked out). Will need to remove tank for repair. Suspect leak is coming from one of the welds near the bottom of the tank but won't be able to confirm until I remove the tank.

Thought about trying JB weld or other similar method, but would really like to weld it up as I don't want to be doing this again anytime soon.

What is the safe way to do this? So far I've read about:

- Steam clean tank thoroughly.
- Purge tank with argon.
- Put dri ice in tank during welding.
- Fill tank with water before welding if possible.
- Run old car exhaust in tank before/during welding
- Don't do it, you will kill yourself.
- Clean and flush the tank and weld it up, repairs like this are made all the time, you won't kill yourself...

What say you?

[tattoomike68]

If its a diesel tank, then steam clean it and weld it. I have done many of them. I even gas welded fitting on to them and nothing happend.

It is also safe to weld a full diesel tank. The ones that scare me are tanker truck size tanks.

[SGW]

I'd use epoxy, myself.....

Years ago my pickup truck developed a leak in the gas tank. The guy at the service station got a "gas tank repair kit" (a.k.a. epoxy) from the local NAPA store and used that to patch the tank. It was still holding fine when I got rid of the truck several years later.

[lynnl]

If it's rusty inside, as it may well be if sitting empty for years, then some kind of sealant coating inside might be a better fix than welding the known leak. There may be other spots on the verge of springing a leak.

The POR 15 paint folks sell a fuel tank repair kit. I had good luck with that.

http://www.por15.com/

There may be other equally effective products, but this is the only one I've had experience with.

[Bguns]

Leak

I would not recommend epoxy or slosh type tank sealer on a dozer fuel tank (unless leak is only due to rust), No shocks, No rubber tires , No springs, every jolt, bump, rock, and grouser cleat hit, transmitted to fuel tank directly. Add weight of fuel to the pounding and I don't see how it could be a permanent repair. Pull tank, clean, and properly clean crack, stop drill (ends of crack) if needed, weld/braze and be done with it. (untill it cracks somewhere else)

[bob308]

i have welded a lot of tanks the trick is to have at least 2 openings that way it will not blow up. also clean it out as best as you can.

[Bentool]

sounsd like a cheapskate fix. junk it, you can't afford it. buy new tank and be done with it.

[billyboy]

welding any sort of empty fuel/gas tank is dangerous no matter how long they have been stood empty or ventilated, only repair them yourself if you are competant, if your unsure how to go about this job then let a professional do it. it would be the safest option for you, im a welder fabricator by trade and this is my advice to you.

bill

[wierdscience]

If in fact it has been sitting for years with nothing in it weld it and don't worry about it.If you want insurance fill it with water or fill it with water and a gallon or two of Castrol Super clean and let it sit for a couple weeks then drain and weld it.

If the bottom is swiss cheeze,cut it out and fab a new bottom then weld it in,it is nearly impossible to patch a rotten tank after all.I have fixed a couple 3-4" round rust pin hole spots by sandblasting it and the surrounding area,cleaning it with acetone and then using aluminum screen wire and JB weld.

[Wareagle]

My take on this situation would be to replace the tank. It it has been sitting for years without any fuel in it, then there is probably a fair amount of corrosion in it. It there is not, then the prior years of service have most likely weakened the welds. The gamble would be a long lasting repair.

As for welding up the old tank, either steam clean the tank, or fill it with an inert gas before doing any welding (or both). You could probably get by without either, but you may not get a second chance shoud you have an unwanted event!

For a repair, the thing to consider are the uses of the equipment. If it is for a business, then what would the downtime cost for a failed repair (lost revenue, wages, etc.)? On a personal use machine, would lost fuel harm anything should the tank start leaking? I'd hate to face my wife after dumping diesel fuel into the soil!

In the end, the decision is yours to make. I have personally taken "short cuts" or gone the "cheap route" only to find that my time had been wasted, and I had to pony up the cash for the new part(s) anyway. Mr Murphy tends to hang out with me most of the time, so I usually will take the hit and get a replacement part in a case like this.

Hope this helps out, and good luck!

[rsr911]

I've welded several gas tanks (as in gasoline) in the past. My trick is to completely drain the tank then slosh soap and water around in it, rinse and repeat. After the soap and water there will be little if anything left to catch fire or explode but for safety's sake I purge with argon from the mig then weld. When I'm done I like to dump in about a quart of alcohol to help dry out any remaining water, slosh the alcohol around then drain. Once I've done all that I let them sit in the sun for a day to dry out.

If it's rusty inside be sure to seal it or you'll be having the same fun my brother in law is having with his '73 TVR, clogged fuel filters. He wound up recirculating the gas through a cheapie glass filter which he had to clean several times and I still don't think he got all the rust.

FWIW my '66 911 tank was sealed with the Por-15 gas tank sealer about 9 years ago and it's holding just fine. The car has very stiff torsion bars so it takes a pounding on rough roads and it's had no effect on the sealer.

[gmatov]

Of course you are all younger people, so none of you would even THINK of using a copper soldering iron to solder the tank. heat the iron, heat the tin with the iron, with flux, pour the solder to it. Permanent fix, no Ka-BOOM.

Had a cousin, a professional, welding a diesel tank, empty, clean, purged. Blew up. Took him some months to die. Bloated up to about the size of the hospital bed from fluid retention. 50 years of welding and he is dead from a little overlook like, mebbe I shouldn't do this. He did, he is dead. You wanna do this, tell your survivors to let us know what the result is.

Cheers,

George

I'm not a zealot, I had both an Audi and an Olds Diesel, with rotten tanks, pulled them, put a hose from a lawn mower into the filler, brazed them, with oxy propane, didn't blow up. I don't know, was I just lucky, or is everybody else, including me, more wimpy? Like we hear so much "Don't NEVER do that" on forums, we get too scared to take a chance on anything. A nation of pussies?

[mrennie]

I've welded a couple of gas tanks before...in both cases I emptied out all the fuel, washed the tanks with soap and water then drained, and then connected a garage exhaust hose to the inlet of the tank and to a vehicle and let it run for at least 30 minutes (there must be a vent or some other opening on the fuel tank for the CO/CO2 to come out of to be effective.) Then I welded the leak. No problems....

...although I was 16 years old at the time. FYI, in both cases I had completely wasted my time at the tanks just rotted out somewhere else within months. In hindsight, unless the leak is a gash or crack at a weld, it is false economy to repair a leaky tank unless it is a very special application and replacements are not available.

[lynnl]

This is something that's always puzzled me, and I've never seen this mentioned in any discussion such as this.

Why? ...would anyone planning to weld on a fuel tank, not (after all the cleaning, purging, etc.) run some kind of fuse or spark generator down into the tank and ignite/activate that while watching from some safe distance???

That would give at least some degree of assurance that there is not an explosive mix still remaining in the tank.

[Wareagle]

You know, that is a great point! I have worked on jobsites where there were welders working with product lines (pipes) that contained flamable liquids, and they would pull plugs out of the line(s) after draining them, and put a torch in the hole to ignite the vapors prior to welding or cutting. It usually made for a loud bang, but it eliminated the risk.

I wouldn't put a torch in the filler neck of a gas tank, but like lynnl says, why not create a spark from a safe distance to ensure that there wouldn't be an unwanted event prior to performing any "hot" work on a tank.

Great idea lynnl!