Gas Tank Repair

[Guest 1930]

1930, I too, have (some big) dents in my gas tank. I like your post about putting water in it. I assume I need to plug all holes but one, and how much air should I put in the tank? I thought about drilling a small hole, and use a slide hammer to get some out, but don't want to add more holes. When you said, "work the dents out", how do I do that?

Hi Willy, I would not drill a hole slide hammer deal, plug all of the holes like you say in a way that the tank can become pressurized, make an adapter type fitting on one of them, doesn't have to be fancy or a time consuming matter, could be something as easy as sticking a fuel line hose on your fuel outlet and then stickin a male hose barb on the hose.

Fill tank maybe 3/4 of the way with water doesn't have to be precise and then give it a few pounds of air, depending on how large the tank is will determine how many pounds I guess.

If the dents on the bottom than keep the water on the bottom as best as you can and as your filling it with air ( not going to take much air, make sure you have a regulator on your air line so you don't put too much in at once )

You will start to see the pressure from the air/water push the dent a little, take yourself a hammer, maybe a soft faced one and start tapping all around the outer ring of the dent.

Whenever you have dent does not matter how big or small, how sharp, whether its a crease or a soft impact where ever that dent is there will be an area outside of the dent that has been pushed up and out, this is what I refer to as the ring above, cant always see it but it is there.

Metal is being stretched when it feels an impact, you need to un-stretch it to the best of your ability by relieving the tension, best way you can do ( with a fuel tank that has and always will remnants of fuel within it ) this is by doing your best to hit it with a hammer in a sweeping motion, I like in many cases to sweep it in toward the center of the dent.

Best I can maybe explain sweeping is imagine your hammer sitting right now on that ring I spoke about above, now imagine your hammer ( still sitting on that ring ) moving slowly in toward the center of that dent, you are going to make this same motion when you hit it with your hammer.

Sometimes if the dent is two extreme and I know there is no way I can do a great job without the aid of some filler ( more fillerthan I care to admit ) than I will push it the other way, ( yes believe it or not when you make the sweeping motion you are pushing and pullin metal ) and keep pullin it ( with reason ) until the area is more subtly dented, sorta trying to hide the mess by making it a little bigger than it originally was but spread out.

We used to shrink metal with torches and a shrinking hammer and or dollies. Metal now-a-days is so thin, harder to get any kind of good results and as always it makes the metal brittle.

Back in the day we would get it ( metal ) glowing with the torch, use our shrinking hammers and dollies which had corrugated faces, knock the dent in what fashion we felt would work best for the job than quench the metal with a wet rag.

Talk about making it brittle, tempering the metal but harder you make it the more brittle it becomes.

I wouldn't suggest trying torch on a gas tank, even if its been cleaned out professionally unless you really know what your doing. If you know though how to use the torch properly you can raise a dent from a tank just by positioning the torch on it correctly, like magic but in my experience this is one of those deals where sometimes you are lucky and sometimes you make a bigger mess.

Water being in the tank and me working from the water side I wouldn't be concerned ( much ) about getting that tank too hot ( water inside isnt going to allow it to happen ) from my small rosebud tip but again I wouldn't suggest this to anyone reading this unless they are confident or just didn't have much regard for a healthy day.

I could go into this further, I really feel a tug too do so but I must refrain as I don't want to hear of anyone getting hurt.....take a metal tomato can, make a dent ( not in the corrugated section, too hard there ) fill it with water and put an air fitting on it, practice with the torch, move it all around not getting it too hot in any one place until you find the sweet spot, once you have found the sweet spot you will know it, you will see the magic of heat, might not even have to ever hit it with a hammer.

I have never met a bodyman that didnt have to put some filler after he was done, you will prob get all sorts of guys P.M you sayin that un-true and to these guys I say they dont know what straight is, let me look at the tank after their supposed filler-less repair is made and I bet I could go surfin on it.

On a fuel tank you dont was to file on it too much, no point in thinning the metal any more than time has already done but you could take out a few high spots if need be with a hand held file ( no not a shop file but a body file ) couple of quick passes is all I would make, no more.

Fill the rest with a skimcoat of filler of your choice.

Good luck with your tank.

Edited April 20, 2012 by 1930 (see edit history)

[R.White]

Good that you have a sound tank to start with, Mike. Did you know that ethanol can attack solder?

I have even heared that it can make the carb floats leak at their seams. I hate the stuff! If it had benefits to the environment, I could sort of understand, but it INCREASES fuel consumption so makes things worse!

Sorry for sounding grumpy.

The horn button is on the steering wheel boss and is not the right one.

Ray.

Edited April 20, 2012 by R.White
cock up (see edit history)

[Guest 1930]

Quote..........Did you know that ethanol can attack solder?...........Ethanol is in all of our fuels, what a mess

[MikeC5]

I didn't know that. Solder! I believe there are still some brands of gasoline that don't have ethanol.

[ply33]

Original poster made no mention of leaks, just dents. So why the discussion about need for a sealer?

I recall when sealers became popular in the the '70s and then maybe 10 or 15 years later the additives in gasoline changed and the original sealers failed and ruined many a fuel system. And I recall people that used the reformulated sealers in the late 80s or early 90s that ended up with equivalent problems later when the gas changed again. The modern sealers claim to have solved all those problems but who knows what is going to go into gas in 5, 10 or 20 years? Why chance it if you don't have an immediate problem?

[1936 D2]

I second that point from ply33! Only seal if necessary - like many pinholes etc.

[R.White]

As has been expressed, it is unfortunate that the authorities have banned the use of effective tank sealants and I for one would not use any of the products that are currently available in the States unless it was as a last resort. I don't think we have had the same problems in the U.K. but that is only my experience and I am in no way smug about it.

The most important point to remember, I believe, is that the ethanol in petrol is only corrosive to the fuel system if it has been allowed to stand for any length of time. The longer petrol is left these days, the more acidic it becomes and will attack the original tank lead lining, or 'tern plate'. A simple solution to the problem is to introduce a suitable additive, now available and which should eliminate the need for tank sealant and allow petrol to remain stable in the tank for much longer.

Ray

[MikeC5]

Ray, is there a specific brand of fuel stabilizer that claims to prevent corrosion from methanol containing petrol? Or is it just by slowing down the decomposition of the fuel that prevents the acidity from increasing?

[R.White]

Good question, Mike. I personally have not yet purchased any of the additives; all I can offer at this stage is this link:

FBHVC Blog Archive FUEL STABILITY ADDITIVE TEST RESULTS

Also my post #33.

[Pete K.]

Mike, I've had great results from a product available most auto stores, it's called "Seafoam".

[MikeC5]

It would certainly make sense to put a stabilizer in there over the winter months or drain the tank and run it out of gas. One thing that occurred to me about ethanol in gas is that ethanol mixes with water and as such, might it not be better have the alcohol and (if any) water mixed than having water separate out on the bottom of the tank? It would seem ethanol is the lesser of two evils.