Removing dents in a gas tank

[Willy]

My gas tank  (1918 DB Touring) has several large dents. I thought of using a slide hammer in a hole, then solder the hole.  Or is it better to have a new tank made?

[Beltfed]

Depends on your skill level, like doing your own work, and how deep your pockets are.  Some would cut a hole in the tank in order to get hammer and spoons inside then weld the hole closed.  Others, and there seems to be many here, just order a new tank.  

[Curti]

I use a Stinger dent puller. It welds a stud on to the tank, then you pull it out with a dent puller.  I just did a tank that way last week. 

[Friartuck]

I like Curti's suggestion. I was never fond of putting holes into something unless absolutely necessary.

[46 woodie]

Any good body shop has a "Stinger" or stud welder and I agree with Curti that that is the best way to pull the dent. The last thing I would want to do is put holes in a gas tank. I just used a stud gun on a small gas tank last week and it worked fine.

[keiser31]

I used water and air.

[Rusty_OToole]

An old timer showed me how they did it on motorcycle gas tanks in the 20s. Sand off the paint and tin the area with solder. Solder the head of a roofing nail where you want to pull, clamp the nail in a vice and pull the dent out. You could do the same with a slide hammer. When you get done melt the solder and wipe off the excess with  a damp rag.

[emjay]

You make it sound so easy, but a dent means stretched metal and the possibility of oil canning.  You might need another skill of the heating and cooling shrink method.  Some are good at it.  

[keiser31]

1 minute ago, emjay said:

You make it sound so easy, but a dent means stretched metal and the possibility of oil canning.  You might need another skill of the heating and cooling shrink method.  Some are good at it.  

That is why I used the water and air pressure method.

[Spinneyhill]

What sort of air pressure did you need?

[keiser31]

8 minutes ago, Spinneyhill said:

What sort of air pressure did you need?

If I remember correctly (it was quite a few years ago...I was young), I used about 3/4 tank of water leaving 1/4 tank for air. I think used about 30lbs to start with and the dents came out with a slightly higher pressure. I have seen guys use less pressure....depends on the severity of the dent.

Edited May 12, 2016 by keiser31 (see edit history)

[cahartley]

Using a compressible agent in a pressure vessel, which a gas tank becomes under internal pressure, is a very dangerous thing to do.

Even at 30 psi if that tank blew it would be a helluva thing....... 

When I pressure tested the boiler on my 60 HP steam engine I filled the boiler to the max, put an adapter in the filler hole and pumped it up with diesel fuel using an electric hydraulic pump from a snow plow.

If something were to let go using non-compressible fluids virtually nothing would happen except leak out a few drops of liquid.

[keiser31]

What I should have said earlier is that my compressor was set at 30psi. It probably didn't get that high before the dent popped out.

[JFranklin]

I have used air pressure but was instructed to use a body hammer not the edges of the dent and it came out. Compressed liquid sounds safe. I figured that if the tank burst it would do so at the seams so wasn't too worried. I used more than 30PSI but don't remember how much more, maybe 40.

Edited May 13, 2016 by JFranklin (see edit history)

[nick8086]

Is this the part?

[Willy]

Thanks to all! I'm going to look into the solder method - that sounds safe. If that doesn't work for me, then I'll try the water/air method. But you're all right - I won't drill into the tank. Willy

[mercer09]

concerning the air method, there are several utube videos where guys blew their tanks up........................ careful with that.

 

also saw one with a tennis ball at the opening of the tank, so as to blow the ball out before the tank-seemed to work well.

 

the videos Im speaking of were for cycle tanks, but the same basic principle. I personally used a blood pressure cuff in my cycle tank to pump out the dent.

[R Walling]

I used to pop out dents in alum truck tanks by filling them up with water all the way and then just use water pressure to pop the dent. worked good on several tanks.

 

 THEN, one tank had a scratch on the bottom and the pressure blew it wide open in a flash. There was no "explosion" just a big woosh, but the tank was destroyed.

 

 Now I just replace the tank, as the liability of a ruptured tank in the future on the road is too great.

 

[Amphicar BUYER]

Use the welded stud method! Avoid using heat as that will affect the metallurgy. If the dent isn't huge or severely creased, this method is the least damaging (only a 1/8" spot on the surface) and give complete control unlike pressureising it. No dager involved either. Any decent body shot will have the tool you need.

 

[Bhigdog]

Fuel tanks are usually made of terne plated steel for corrosion resistance. Terne is a low temperature alloy that solders easily. The high heat of spot welding studs on the tank will burn off the corrosion resistant plating in dime sized spots both in and out side. Your dent free tank will be very vulnerable to interior rust.

Soft soldering studs (galvanized roofing nails are ideal) for the pull will not harm the terne plate...............Bob