Hot Rods Welding on gas tank

I was just wondering what rod you would use.
If it was brazed at first you would be hard pressed to get all that ground out.

 

I've welded a few tanks and most recently added a sump to one my projects. What I did was us Dawn dish soap and really, really hot water. Fill it with a 2-3 gallons, plug the filler and fuel sending unit off and start swishing it around. Drain and repeat until it stops smelling like gasoline.

As far as welding, I just mig welded my sump in. Check for leaks with water and spot weld the pinholes if needed.

 

I will not attempt to offer advice on this one. I did however survive an attempt at welding a filler neck on to a tank. I had flushed it with a lot of water. Let it air out for a few hours. Then followed some really lame advice of warming up the tank to cause the vapors to come out. Well they came out alright and the last thing I remember was "KABOOM". There was a gouge in the ceiling of my garage from the tank and I couldn't hear out of my right ear for a while. Man I really wanted to use that tank but it was ruined. It didn't blow apart into pieces but it blew up like a balloon.

 

And you folks thought I was silly for the ear plugs suggestion.

 

I take out the sender and the cap, then run the outlet of a vacuum cleaner into the tank. I let it go for twenty minutes or so, until there is no smell of gasoline in the air coming out.

Then I leave the vacuum cleaner running while torching on the tank.

The vacuum cleaner pumps out a large volume of warm air, which does a great job of evaporating any residual gasoline. Plus, any flammable fumes that could be produced when brazing/soldering/welding are immediately carried away.

I am reluctant to use any strong cleaner or detergent in the tank, as it may remove the "terne" coating that remains, leaving bare steel that will rust quickly.

 

Thanks for all the replies. The tank is new with maybe 10 gallons ever ran through it so I’m not worried about varnish build up. I bought the car as a project with the tank in the deal so I’m not the original purchaser, so warranty is kinda out is the question. My only thinking is it’s designed for fully boxed street rod type application and not stock replacement for a frame that naturally twists. Had it Sitting out for a couple weeks now. Thinking flushing with warm water and dawn a couple times then argon purge it and check it with a match. Definitely one of the more critical parts of our hobby if we hope to hot rod anouther day.

 

Bleach is an oxidizer why would you put in a steel tank?

 

Have always used this method, run exhaust into empty gas tank for 10 or 15 minutes before welding and leave exhaust running till welding is done....
Have never tried dry ice, but I like the idea, think I will try it the next time the need comes up......

Lynn

 

If your car exhaust has enough unburned fuel in it to burn you need to have it looked at.

 

I wonder how those car flame throwers work?

 

Finding someone who will fix a gas tank has gotten to be virtually impossible. Even our high dollar tank repair and coating place went belly up. Twenty or more years ago our local shops quit doing it, so I started doing my own repairs. I've never had a problem but it always brings out the cautious side of me. I have done the rinse with Dawn and purge with Argon mostly with good results, I may try the dry-ice next time.

 

"Have always used this method, run exhaust into empty gas tank for 10 or 15 minutes before welding and leave exhaust running till welding is done...."

Sounds like pretty much the same idea that I use, and probably more available in the old days.

 

By pulling the choke until the car didn't hardly run or by injecting propane in to the tail pipes.

 

Yup. That's what we do.

 

Fuel injectors and spark plugs for the big boys.

 

Clean it out as well as you can ,set it in the middle of the yard . wad up about two foot of newspapers in a rope, put one end in the tank ,light the other end and when it fall into the tank you will know if its safe or not . Kinda cool when it blows up also.

 

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I've seen old times do the torch trick, usually with the tank around the corner and they reach out with the torch. Cutting exhaust off cars, I've had a couple of unexpected POPs from fumes that built up in the mufflers.

 

Would be more reassuring if only one common way would be the only answer from all. Kinda gives the impression that no perfect way has came to the surface yet. It always scares me when the scrap yards tell you what size hole YOU have to cut in a gas tank before they will accept it and they tell you THEY will not do it for you. I always think, they are in the business and won't do it theirselves ! ????

 

There are many ways to skin a cat, just some better than others. As testified here they have all been successful. Choose and use what’s available to you and the one you like the best. Bones