Chemist Needed!

[KenBolton]

I found a very minor gas leak around the steering column support bracket in my newly restored pickup. It has 800 miles on it. The tank was acid striped, sealed and painted. I can see a crack off to one side of the bracket that is very narrow and less than one inch long. I hate to remove the tank but will if needed. I was told some have successfully jacked up the front of the vehicle so newly added sealer will run to the back of the tank around the bracket. Has anyone here had success with this approach? Am I really out a lot if it doesn’t work and I have to pull the tank?
I replaced the original steering column bracket with a 31 bracket. The tank is drained. I read another post recommending rinsing with wax and grease remover and then a final rinse with Acetone. I have these products but am wondering if either or both will destroy the liner I would just as soon leave unmolested?

[AL in NY]

I would try sanding the area of the crack. Then rough-up the area with a scribe and apply some JB Weld. It's very gasoline resistant and will bond very well with the tank metal.

PS Drill a small hole at the end of the crack to prevent it from growing longer

[SAJ]

Chemist here Ken!
I agree with AL. My roadster leaked badly. I drained the tank, dried the crack from underneath with an IR lamp. Ground the area with a burr in a dremel to remove an old resin repair that had failed, wiped with acetone, heated with IR bulb again and applied a 24 hour cure epoxy that I thickened first so it would not drip. Then after it had gelled I cured it for 24 hours at about 70 deg C with the I R lamp from inside the car. I monitored the temperature until it stabilized with an IR thermometer gun, so it did not get too hot and blister the tank paint.
I am sure the 24 hour JB weld would work just as well, but probably not the 5 minute mercaptan-curing version.
I made my own putty up because I own a factory making filler products, fibreglass resins etc so I have all kinds of epoxies, thickeners, thixotropes etc in my laboratories.
I am an lndustrial Chemist. Notwithstanding that, for our leaky Tudor, there was cracked solder in the area. So I ground it clean and re-soldered. That is not easy upside down under the dash!
Both have held for 10 years or more and tens of thousands of miles.
If the epoxy repair fails I will just do it again for another 10 years or more.
Removing the tank was not an option on the 1930 roadster because a previous "restorer" somehow bonded the dash rail in and it would destroy the paint and probably the rail itself to get it out.
In both cars I installed the later column brackets and left-off the original bracket caps and mounting rubbers so there is no load on the crack repairs.
SAJ in NZ

[KenBolton]

Thanks for the guidance! I cleaned up the area and found solder. The crack must be very small as now that the paint is gone I can’t find it! I will scratch it up and fill with JB Weld. I may still want to add additional interior sealer so, is degreaser-Acetone rinse the way to go?

[History]

I had forgotten that I'd repaired a crack in a gas tank on a Japanese mini truck I have. It has held for years with no seepage at all. I know preparation is key to success. Good luck and let us know with photos if you don't mind.

[Benson]

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[katy]

I will scratch it up and fill with JB Weld.

Good luck w/that, I once used JB weld to hold the baffle on a gas cap and the JB weld failed shortly after.
I suspect the ethanol in the gas was the culprit.
Maybe current production JB has been formulated to avoid that?
AL in NY in post #2 says JB is "very gasoline resistant ".

[rotorwrench]

A good quality tank sealing material used in aerospace is Proseal PR1422 B1/2 and it's available from Aircraft Spruce. It has a shelf life so a person can sometimes find the stuff on Flea-pay for less money after it passes the shelf life. It ain't cheap. The SEM kits are a one time deal unless a person cuts the thing apart to keep the activator separate from the main ingredient. The parts have to be completely free of any contaminant for it to bond properly. Fuel likes to stay in a crack by capillary action and this affects epoxy bond as well. It would be better if the tank is upside down where compressed air can be used to blow the residue out of the crack.

It is common to get fatigue cracks around the steering column support. It is subject to all sorts of motion during the operation of steering the car. It's almost impossible to stop that unless the tank is cut open and the area is properly reinforced. This requires temporary removal of the steering column support in most cases for a good long lasting repair. A soldered patch on the outside will work longer than any sealant application since they are really just a temporary band aid for the problem. It just flexes too much in that area.

Finding a good radiator man is not as easy as it once was. All the plastic radiators in use now days have made the brass & copper radiator repair business a niche market business.

I just wish some company would start manufacturing accurate reproductions of the model A gas tank designs. A person can purchase almost any other type but the model A designs.

[KenBolton]

Can anyone answer the question of whether or not the wax and grease remover and/or Acetone will destroy the existing liner or nearly soften it for better adhesion?

[rotorwrench]

Acetone is what most folks use to remove the common white tank sealers. Wax and grease remover should be OK since it is closer to gasoline in make up.

[GeneBob]

The original formula JB Weld is much tougher than the quick set up version. However, you can find gas tank repair epoxies at your local auto parts store. It is about as thick as chewing gum so it won't get pressed into a crack but if the surface is clean and roughed up, it should seal on the surface.

[Ernie Vitucci]

Good afternoon all...I would also give some thought to the new support bracket that most of the major suppliers have...It clamps to the steering column and under the dash and relieves the pressure on the clamp attached under the tank. We can patch the current leak, but people tend to pull down on the steering wheel when they climb behind the wheel which is what normally causes the leak...The new bracket sort of makes sure that a good leak patch will last longer than most of us will! Ernie in Arizona

[Ivan in southeast va.]

I would take care of the outside of the tank first and leave the inside alone for now.

[SAJ]

KenBolton. Wax and grease remover is a weak solvent. Petrol is stronger. Wax and grease remover is formulated as weak enough to not attack acrylic lacquer.
Acetone will probably dissolve or peel the tank lining. I wouldn't use it except on the outside on a rag.
And acetone will attack most paint types on your tank and dash if you manage to splash it about.
SAJ in NZ

[old ugly]

i had a leak in the fuel tank of my model b in the 1980s i ran a small bead of "sealall" on the source of the leak and it never leaked the following 25 years that i owned it.
maybe not your choice but that stuff worked for me.

not a chemist

[daren007]

Air plane repair shops should have Pro Seal in bulk cans both sealant and hardener in separate cans. Sealant white and hardener black. Mix to a gray color. The mechanic can help with this. They will most likely give you some of each so you don’t have to buy a large quantity.