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How to fix small hole/leak in fuel tank?

33K views 25 replies 19 participants last post by  Skinnykid 
#1 ·
I just "Evapo-Rust'ed" the tank on my 1980 cm400t. It seemed to get about 90% of the rust out, but it also brought a small hole to my attention. This tank has been soldered and/or welded numerous times from the looks of it. The hole is about 2 or 3mm (tiny), but still leaks a good amount.

My question is: How do i fix it? Should i solder it, weld it, or can JB Weld be used on a hole this small?

Any advice would be greatly appreciated. -Mark
 
#17 ·
If you decide to go with the KREEM sealer I can save ya some cash.I've got 2 of the jumbo packs for tanks up to 5 gallons.The kits are new and still wrapped in the original plastic.Average retail price is $54 per kit.I'll ship the 3 bottle kit to your door for $40...here's a guide that is as good if not better than the instructions that come with the kit.Thanks,Junker.
How to use KREEM Gas Tank Sealer Kit to seal your gas tank

**This procedure is best done outside.

**Remove any petcock, cap and crossover hoses there may be and seal all openings except the fuel inlet.

**DO NOT get any Tank Prep A (diluted or undiluted) on the painted surface of the tank as it will damage the paint!

How Much Do I Need?
For small tanks (1-5 gallon) use 1 pint bottle of Fuel Tank Liner.
For larger tanks use 1 quart of Fuel Tank Liner per 20 gallons of tank capacity.
Thin Fuel Tank Liner with Methyl Ethyl Ketone to brush or spray on.


#1 - Clean and etch the inside of the tank:
The inside of the tank should be completely free and clear of all loose particulates and corrosion. Even more importantly, it must be totally devoid of any and all oily substances, including any and all traces of gasoline, oil and grease.

Begin Here If Using An Old Or Used Tank - An old or previously used tank may need some extra prep work to get ready for the KREEM treatment. If your tank is really greasy or very rusty begin with this extra step. If you have a unrusted new tank or lod tank in really good condition skip ahead to the application of the Tank Prep A.

Pour about a pint of liquid degreaser full strength into the tank and slosh vigorously with all the openings capped off. Do this for several minutes, and don't forget to invert the tank and get all of the surfaces degreased up around the fuel inlet, as well as the very top of the inside of the tank.

If the inside of the tank is really rusty or has particles stuck to the inside surfaces add several loose nuts and bolts to the degreaser to help break loose the surface contaminates. You may also use a couple 8" lengths of medium size linked chain or anything that will rub against the inner surface and can easily be removed.

Next, add about 1/2 gallon of the hottest water you can get to the degreaser still in the tank and slosh it around again for a few minutes. After you are quite certain that you've degreased all surfaces pour out the entire mixture and remove anything you inserted to help scour the inside surface (nuts, bolts, chain, etc.).

Now pour about a tablespoon of hand dishwashing liquid and about a gallon of very hot water into the tank and slosh thoroughly. Follow with as many cold water rinses as necessary to remove all trace of the dishwashing soap.

Now you are ready to use the Tank Prep A (Wash/Cleaner) that came with your KREEM Tank Prep Kit. This will completely clean and etch the inside surface of the tank.

Begin Here If Using A New Tank - You may begin here with a new tank or begin at the extra cleaning steps listed above if you feel your tank can benefit from the more rigorous cleaning required with old or previously used tanks.

Pour 2 to 2 1/2 gallons (depending on your tank volume) of the hottest water you can get into the tank and add Tank Prep A. Slosh the mixture around for several minutes being sure to get all inner surfaces etched including the inside top and fuel fill area. Sit the tank down for several minutes (10 - 15) between sloshings to let the Tank Prep A solution work. Prop the tank in different positions so the solution contacts all inner surfaces. Leave a small opening in the fuel filler plug to allow gas that is produced during the etching process to escape.

Carefully pour out the Tank Prep A solution into a container for storage so you may use it in the future. Flush the tank with cool water. Inspect the inside of the tank to be sure all rust has been removed and the inner surfaces are etched. Reapply the Tank Prep A solution if needed. Flush the tank with cool water until the rinse water no longer foams and all trace of Tank Prep A is eliminated.


#2 - Remove all water from the inside of the tank:
Perform this step in a WELL VENTELATED area. Immediately pour Tank Prep B (Conditioner) into the tank full strength and slosh it around so it contacts all inside surfaces. Pour the Tank Prep B out and immediately coat the inside of the tank with Fuel Tank Liner.


#3 - Coating:
Pour entire bottle of Fuel Tank Liner into the tank. Coat the interior surface by slowly rotating the tank in all directions. When all interior surfaces have been coated a large excess should remain. Let the tank stand for 10 minutes with the fuel inlet open. Seal the fuel inlet and rotate the tank again to recoat all inner surfaces. Let the tank stand on a different side for 10 minutes with the fuel inlet open. Repeat this process until the tank has the desired coating. Do not let the excess Fuel Tank Liner pool and dry. Drain off excess Fuel Tank Liner for later use.


#4 - Drying/curing time:
Unseal all tank openings. Allow the coating to air-dry for at least 24 hours in a well-ventilated area. If possible extend the drying time to 96 hours (4 days). A nozzle of a low pressure air compressor blowing into the fuel inlet and out another hole can shorten the drying/curing time.
 
#24 ·
I have welded a lot of tanks from rust or collision damage. and each tank presents a different challenge. Sometimes the metal is too rusted to plug weld and requires an extensive patch to be fabricated in. Regardless of repair type, if any heat or welding is to be used, I recommend using dry ice in the tank during this process to eliminate any fumes from igniting.
 
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