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Old 12-10-2009, 07:44 AM
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Default Diesel Fuel Tank Repair

I am trying to figure out the best way to approach fixing a small leak that developed in the fuel tank of my Case skid loader. As many of you probably know, the fuel tank is built in and an integral part of the machine. So, I am not able to remove the fuel tank.

It appears that the leak is coming from a weld joint about 3 inches from the bottom. After wire brushing and cleaning the area it looks like the leak is from a pin hole in the weld that suddenly decided it was time to leak. I do not see where I damaged it in any way because the paint is in excellent shape with no scratches or anything.

I would like some non-welding fixes if possible. I have heard about people welding on diesel tanks with no worries about fire or explosion, but I am very leery about welding on anything that contains, or has contained flammable substances. The old guy down the road told me that since I have about 3/4 of a tank of fuel, there is no way it can explode because the leak is below the empty part of the tank where any vapors would be present. Even then he say's you do not have to worry about diesel fuel vapors exploding......I don't know about that, the fuel is designed to go bang so it can run the engine. Also, I do put Power Service diesel fuel additives in the fuel, and on the containers it states that the fuel conditioners and injector cleaners are flammable. Anyway's, is there something like JB Weld that will stop diesel fuel leaks. My problem is trying to keep the area dry so whatever leak repair substance I use would have a chance to cure. Even if I did want to try to empty the tank, I think the fuel residue would keep seeping from the pin hole leak for eons........maybe not.

The other concern I have is that any type of substance I could use that needs time to cure, will be curing in very cold temperatures because I have no place to put the skid loader where it is warm

Any explosion or fire proof repair methods would be greatly appreciated.............thanks.
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Old 12-10-2009, 08:34 AM
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I used a two part epoxy fuel tank putty on a friends car once with success. We didn't empty the tank just mashed it in the leak area to press the putty in the hole. It hardens pretty good on its own without applying heat.
It would be worth a try as a first option because you could always grind it off.
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Old 12-10-2009, 08:38 AM
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If it's just a small leak, fill the tank and do a quick tack weld. The fuel will keep the inside weld cool. Or you could drill out the pin hole to what ever size tap it and install a screw with a rubber washer. If it were mine I would just tack it.

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Old 12-10-2009, 09:41 AM
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I have seen a very experienced pipe line welder try to fix a small crack on a liquid filled tank (50% water,50% glycol), and it was an frustrating job for him. He ended up chasing that crack for several inches before finally managing to get it under control. The glycol mix was at ambient temperature at the time (below freezing IIRC), which may have contributed to the problem.Preheating may have helped, but we didn't feel like pumping out 250 gallons of fluid, then heating a 6" piece of pipe, plus the bulkhead it was welded into.
I think that you might run into the same problem with cold diesel fuel.Try carefully peening the hole with a punch to try and get the leak slowed as much as possible, then get it welded when the temps are nicer.My $.02 (Canadian)
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Old 12-10-2009, 09:56 AM
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Originally Posted by randy_m View Post
If it's just a small leak, fill the tank and do a quick tack weld. The fuel will keep the inside weld cool. Or you could drill out the pin hole to what ever size tap it and install a screw with a rubber washer. If it were mine I would just tack it.

Pat , I have welded on live Natural Gas lines , it takes three elements to start a fire , fuel , an oxidizer and an ignition source . As long as the triad is not complete you are safe . With diesel fuel above the leak , oxygen can not get to the weld on the inside of the tank . You might have a flare up on the outside of the tank but it would not amount to a large fire . If you have a mig welder , purge the tank with your shielding gas to remove any fumes that are in the tank .
Clean the area well and then with stick welder with 6010 or 6011 weld downhill with a "whipping" motion to cover the pin hole . It might take a few tries to close the hole , if you do not get it on the first time grind off weld you deposited and start over . Putting weld over weld can cause more problems by spreading the leak over a larger area .
You might want to run a little hotter than normal when try this .
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Old 12-10-2009, 10:23 AM
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I welded a patch on a diesel tank on a Cat loader using this method.
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Old 12-10-2009, 11:46 AM
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Thank you for all of the suggestions. After reading the response from cramd, I followed his advice. First I put the cup wire brush on the grinder and removed all the paint in the immediate area. I then took a punch and smacked it several times with a hammer in the very small area that it was leaking from. I then wiped the area off and left it for about 20 minutes. To my delightfully surprise after going back out and looking at it, I could see a very small (pin head size) bead of diesel fuel that had escaped. Tomorrow comes part 2. I am going to grow a pair and follow some of what Digr posted and fire up the Trailblazer and dab a little 6011 on it. If it goes boom, I hope it takes me with it because I do not want to be as LW puts it "licking the bus windows". Actually I believe it will work out very well because there should be nothing to ignite. I will let you know how it goes/went......thanks again.
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Old 12-10-2009, 01:32 PM
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Old 12-10-2009, 02:31 PM
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I remember reading in one of my off-road magazines that someone makes an epoxy that you can slap on your oil pan if you bash a hole in it, while still full of oil. The oil acts as a binder, helping the epoxy cure to the metal. I don't know if that would work with diesel, but since it's petroleum based, it might work if the welding doesn't.
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Old 12-10-2009, 02:31 PM
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I welded up a couple of small leaks in a diesel tank. Like others have said, make sure the fluid level is above the weld area and don't burn through.
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