Forum Discussion

opnspaces's avatar
opnspaces
Navigator III
Mar 07, 2020

What can I use to get water out of a gas tank

The gas tank is out and sitting on the ground. I need to solder a fitting back on without blowing myself up. I've done this before by washing the tank out and letting it sit in the shed for a few days first. But I really would like to turn this repair around today. Any ideas how I can safely get a flame close to an empty gas tank?

I've thought about just filling it with water, but I fear the water would absorb the heat and make soldering impossible. If I wash the tank out, how can I get the residual water out before reinstalling? Would swirling a few bottles of 90% rubbing alcohol around in it do the trick? Can anybody think of something better to use, something that is fairly readily available off the shelf?

15 Replies

  • We soldered with the tank full of water. A small bubble of space at the top won't let the water absorb all the heat or allow enough gasses to collect to be dangerous. The only thing special I recall doing was adding a few bottles of gas line antifreeze to absorb any residual water.
  • For drying out a (car) tank, I used a shop vac to blow air into the tank. It naturally heats the air a little and after 45 minutes, it was bone dry.
  • A friend of mine that did welding said the best way to deal with a gas tank is to wash it thoroughly 3 times, steam the inside twice, and then give it to someone else to deal with. :)
  • Get a small gas engine eg lawn mower, edger, etc. connect the muffler to a small flex pipe. Flex conduit is fine. Secure it into the opening of the tank. Start motor. Weld.

    The CO from the motor pushes the o2 out so no explosion. Seen it done many times at the welding shop near where I grew up.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,300 PostsLatest Activity: Aug 13, 2025