welding on fuel tank

[WS6]

Don't hate on me too hard for this. I'll be putting my LT1 into my TA this summer and would much prefer an in tank pump compared to an external pump. I'm on a very tight budget so buying a new tank and welding on it is not really an option. So I was wondering if welding on my current tank can be done safely? Also, does anyone know what pump setup should work on my second gen?

[toxicz28]

So I was wondering if welding on my current tank can be done safely?
Yes, it can. You would have to purge the tank (fill with argon, and have the argon flowing continuously while you are welding).
Would I recommend that you do it, absolutely not. $300 (Year One's price) is cheap insurance compared to what it could cost if you attempted to weld on your tank and something went wrong:drive2:. Good luck!

[Mathius]

Yes, it can. You would have to purge the tank (fill with argon, and have the argon flowing continuously while you are welding).
Would I recommend that you do it, absolutely not. $300 (Year One's price) is cheap insurance compared to what it could cost if you attempted to weld on your tank and something went wrong:drive2:. Good luck!

I agree with what he said above.. on a motorcycle tank you could probably get away with cleaning the tank with soap and water.. I've done that in the past.. Let it soak overnight, drain it.. repeat until all fumes are gone... but there's no way you're getting water down that filler neck and draining it back out successfully without leaving crap in your tank.

Something to consider is how much argon are you gonna go through? I know you're on a budget, but it might be cheaper to have a shop do the work.

I have heard so many shade tree stories, or urban legends about welding on gas tanks. I always wanted to see Mythbusters do an episode on it. I even suggested it on their web page, but it was buried among millions of suggestions.

I know the argon thing works.... I know the soap and water thing CAN work.

Some of the OTHER things I've heard over the years:

"Just hook the end of your tank up to your exhaust.. that will purge it"

Except what do you do when your car is running rich and pooring more gas fumes into it?

"Dry Ice will purge it"

No comment on this one. Never worked with dry ice... don't really want to. How do you get it into the tank except in little chunks that you have to try and remove?

My personal favorite:

"As long as you open a hole at both ends it won't explode on you. A spark will just blow right through and you're good to go."

Sounds feasable from a logic standpoint... the flame/explosion whatever would seek the path of least resistance before destroying something... it's when pressure builds up that it backfires in your face right? Except that still sounds awful risky to just try.... how much of a "blow through" are we talking here?

Mathius

[parsonsj]

I've read that filling the tank with water can work. I've never done it though.

jp

[toxicz28]

Dry ice is just solid CO2. Once it melts,it's a gas. There's nothing to remove. Theoretically, other than displacing some of the vapors, I don't know if dry ice would be the right choice.

I've heard of someone trying the water thing also. The op's question actually reminded me of the story.

The guy had the tank propped up between his legs and filled with water so he could braze the filler neck back on. Well, there was a small pocket that couldn't fill with water and the gasoline vapors collected there, right around the filler neck area. When it blew (because it did), I'll give you one guess where the neck went. :eek:






Yes, it went THERE, right into the twig and giggle berries!

The $300 is well worth the piece of mind to me. And, if money was that tight,:idea: I would wait until I had the money to do the swap.

Come to think of it,I never asked what are you planning on welding to the tank? Are you going to have to cut the tank first? If yes, what will you use to do the cut? If sparks are involved, guess what? You'll need to purge the tank while you cut too.

[XLexusTech]

Back in the day .... we used to do this all the time. We would run exhaust gas into the tank while welding.

Same principle as argon but free..

[MirandaBuilt]

wash it with soap and water really good!!! and weld it. if you smell gas keep washing.

[buds87gn]

I've read that filling the tank with water can work. I've never done it though.

jp
Thats how i installed my sump, i flushed it with water for about 10 minutes. I will admit, i was a bit nervous making the first cut

[WS6]

I had heard the fill it with water line before and thought I would do that to cut the opening in the top. From there, I would drop in and weld the recessed patch in place of the cut out section. The recessed patch would have the lock ring for the drop in OEM style pump as well as the fittings for a return line. I just wasn't sure I could weld metal with water on the back side of it. I think I'll look into a new tank or go with an external pump for now. I was also thinking about baffling a stock tank as well so that the fuel stays around the pump versus building a sump section

[jpdeuce]

Water, Argon, Nitrogen, whatever. No Oxygen equals no flames. Its gotta have O2 to burn.

[Vegas69]

Soap and water and your good to go.

[pimtina]

I took my tank to a radiator shop, had them clean it, took it to my shop, cut it, welded on it, no problems. Cost about $40.

[critter]

I've worked my tank a couple of times. Both times I filled it with water and kept water running through it for a while before doing anything. No Boom at my house.

[MickMc]

I welded on my gas tank last week.
I added a drain and a return line.
I hope you're a good welder because that tank is thinner than you think, and it can't leak when you're done.


I was told a long time ago, by a guy here in town that built all sorts of race cars, before I took him a gas tank to weld pickup lines on, to take the tank to the car wash and use the spray wand and spray that tank with soapy water until there was no more smell.
I took my tank to the car wash, used a half roll of quarters and let the tank dry overnight. When I took him the tank he smiled and I picked up the tank the next day, very nicely welded. That was a few years ago.

Mick

[WS6]

I just though of something. My tank is galvanized I do believe. I thought welding on galvanized steel wasn't possible. Or did I just have the wrong settings any time I tried it in the past?

[Twentyover]

Zinc needs tobe ground off. Don't breath it when welding, it will make you sick

[MonzaRacer]

OK first of all at rad shop we used Trich 111, but thats regualted now. So as for tthe exhaust idea, your supposed to hook it to an exh pipe and let car run hot exhaust run for a while, the heat will cook gas out of metal, actually the reason for washing is to get residual gas out. IF you let it set out in hot sun for few days it does same thingbut better safe than sorry, if yuo can see fumes its flammable.
I also agree, tanks are much thinner than you think.
But Ido like filling tanks with water while welding. Then the running car exhaust does help dry them out.
Good Luck

[Samckitt]

1978 through 1987 Monte Carlos all used the same fuel tank so an injected sending unit from an 80's G body would work in an older model. Any chance the newer F bodies sending units would work in an older TA tank? Then you don't have to do any welding on it.

[WS6]

I'll be attempting to use my 96 pump setup. I still have to cut a hole, and I'm not sure how to mount the setup to the tank like the factory did in 96. I figure there's going to be some welding involved.

I guess I need to scan the fuel system forum and look to see how to install a late model pump setup into an old tank.

[Mathius]

I just though of something. My tank is galvanized I do believe. I thought welding on galvanized steel wasn't possible. Or did I just have the wrong settings any time I tried it in the past?

Welding on galvanized metal is entirely possible, although some people find it more difficult than welding bare steel. The coating will burn up making the weld pool react differently and when finished you will often find an almost foamy residue from the burnt up coating.

Welding on galvanized is done all the time in the sheet metal industry, Even though welding galvanized is NOT good for your health.

When I first got into welding, my original instructors told me as Twentyover said before me to grind the coating off first. But most guys in the sheet metal industry that I have dealt with won't take the time to do that.

Honestly, if you want yourself to be as safe as possible, you should always weld with a respirator on, regardless of what you are welding. We all know about the guys who stick welded for 40 years and now are dealing with the consequences now late in life, but almost everything you weld gives off harmful fumes.

Even the byproducts of welding stainless have been found to be harmful to your health. There is a large thread related to this on Chevytalk right now. Most welders do not use respirators when welding, but everyone should. We're not necessarily talking about stuff that will effect you later in life either, but stuff that could kill you NOW if ingested enough.

Also, a respirator or at least a dust mask should be worn at all times when grinding or using a cutting wheel. The shreds of fiberglass dust that are created from the wheel are harmful enough for you by themselves, but why people would think that breathing the stuff while grinding galvanized coating is less harmful than breathing it while welding is beyond me.

Mathius

[WS6]

Check it out! I didn't blow myself up.

https://static1.pt-content.com/images/pt/2009/06/PICT1023-1.jpg


Thanks for all your help and info everyone. It wasn't bad or scary at all. When cutting out the tank top off my LT1 tank, I had it filled with water and it flared up once. No big deal at all. Burned through a couple spots where the new panel didn't fit up to the tank as tightly as I wanted but I got those welded up in the end.

If you see anything I am doing wrong with my welding, feel free to let me know. I'm still in my early leaning phase and obviously have a ways to go before I'm good.

Thanks

[Mathius]

If you see anything I am doing wrong with my welding, feel free to let me know. I'm still in my early leaning phase and obviously have a ways to go before I'm good.

Maybe it's just a poor picture, but it looks like your welds have very little penetration at all most of the way around. I see the rolled edge that looks to me like weld sitting on top, but not burned in well. If you look in the lower right corner of the picture where the welds are located, there are a few spots where it looks like you got good penetration, but if I look straight along the bottom of the picture, I see a clearly defined line where the weld looks like a log sitting on top of the metal.

I could be wrong and it could be a bad perspective in the picture, but did you do any type of leak testing yet or any destructive tests on your previous welds?

Mathius

[WS6]

Thanks Mathius. I believe you are correct on me not getting good weld penetration. My welding has gotten better as I have progressed with this project. I actually have another thread I'd like you to look at there to if you could.

So the weld should be flatter and look like the wire has melted into the the tank and cover? I will be leak testing the welds when I put gas into it for the first time. I know this isn't proper but it will be ok. I won't be driving the car much for various reasons so it's no big deal if I didn't get it right the first time. I have done some destruction testing on my welds and they looked similar to these. The test pieces held up well but I doubt it would pass any sort of certification. At least I would hope the certifications would be more stringent. Then again, I may just be knocking myself because they were ugly welds.

If you notice the ring of obvious heat penetration around the pump ring, can you see or tell anything about the weld penetration for the welding that I did on the underside? The welds looked similar to the top ones. I think what my problem was with the tank, and I'm basing this on how I have done since then, is I was moving too fast because I was worried about burning through the tank. Could this have been my problem?

Thanks

[Mathius]

If you notice the ring of obvious heat penetration around the pump ring, can you see or tell anything about the weld penetration for the welding that I did on the underside? The welds looked similar to the top ones.

It looks like you're getting good penetration when you get the metal to burn through to the other side like that, but weld penetration and weld strength are not always the same thing. You want a nice penetration all the way to the edges of the weld without having undercut.

Undercut is hard to explain without a visual, but basically you burn into the base metal but you don't leave the puddle there long enough to fill the hole you burned.

Given that the placements of these welds aren't likely to be under a ton of structural stress other than possible gas build up in the tank, you may never have an issue with them but it's always best to do your best.


I think what my problem was with the tank, and I'm basing this on how I have done since then, is I was moving too fast because I was worried about burning through the tank. Could this have been my problem?

Thanks

It could very well have been your problem. Again, you want your weld to burn into the edges of the metal as opposed to just having a weld sit on top of it. So yeah, if you're moving too fast, you're depositing metal, but maybe not sitting there with the puddle long enough to burn in well.

And again, your welds might be ok, it might just be bad photography. But from the pictures, it looks like you have a log of weld sitting on there, instead of having good penetration.

Mathius

[WS6]

Thanks Mathius. Based on what you've just said and what I was seeing and doing with the thicker metal on my transmission tunnel, I think I was moving too fast and the metal is simply deposited or partially burnt in on the tank. I had so many issues with the new panel warping terribly that by the time I got the welding the panel onto the tank itself, I was very worried about warping the tank. I should have known that the larger amount of metal that is the tank would take the heat much better than that small panel. Live, learn,and ask questions.

Thanks