Dry Ice

[pomona51]

I heard that you can get dents out of your gas tank by using dry ice. Is this even possible and if it is will it get all kinds of dents out even creased ones. How do you go about doing something like this. If this does not work how much do you think a body shop would charge for getting the dents out.

Thanks Jake

[thedeatons]

I've heard of the dry ice technique also, but am not sure of the process...

You're looking at some good money from a body shop, that's if they know metal work... most use filler these days...

Sorry I couldn't give exact numbers.... FYI - Mike at Vintage is charging me about $400 to do my tank and forks, and the tank has a couple good dents in it. That price is color matched with all original decals and the tank done inside.

[Rasuel]

The dry ice idea would work in theory, but you would need one helluva seal to make enough pressure inside to force out dents, i dont know how you would seal it up that tight. As far as body shops go, i think they would have to use either bondo or fiber glass. Its pretty hard to knock a dent out of a gas tank because unless you cut a chunk out of it, bang the dent out and weld it up again, i dont know how you'd get inside and have enough room to swing a hammer. If you want to try the dry ice idea its pretty easy once you seal the tank. Just put a bunch of dry ice inside and when it melts it creats a gas which in a sealed invironment creates pressure (same idea as baking soda and vinagar in a balloon). The only problem I see is making a good enough seal that there is enough pressure to force out a dent, but not so much you dont blow up your tank. You would need a relaese valve of some kind... thats as far as I can get you, hope it helps.

[willcamach]

ive heard of people just filling tanks with water and letting the water freeze as the water freezes it expands and takes out the dents but you have to be careful not to destroy the tank. iknow people also use this technique on pipes also.

[Huffa]

Hmmm :wondering , that sounds backwards because it's when you heat water up that it expands.

I had a dent knocked out by a body shop that just used a tool on the inside. You would turn something on the tool and it would spread out inside the tank and knock the dent out. This was more of a knee dent though with no crease.

I also popped a dent out by filling tank with air through the petcock. That was a good 20 years ago though and don't recall how I sealed the gas cap opening totally. It did work though but it all depends on the type dent and how thick the gas tank metal is.

[Somekindofjerk]

This might sound stupid but put toilet bolw cleaner and alluminum foil balls in. that makes enough pressure to blow up a bottle. mabey it would work? I might even try that on my tank.

[conig]

water expands when it freazes, I have wanted to try this but my gas cap won't seel up enough. there was a hole drilled into my gas cap.

[pomona51]

Thanks for all the help. I want to try the dry ice put like some of you said i dont want to blow up my tank. Maybe i will try to pick one up on ebay and try it that.

Thanks a million

[hrc200x]

Some kids many years ago were behind a grocery store and found some dry ice the store had threw out. They put it in a glass 20oz bottle and put the lid on. The bottle blew up and the kid was full of glass. The stuff can be dangerous so be careful.

[dblshockpower]

Anyone ever take their tank to an auto dent doctor? bet they'd have a tool to pop out the problem! I hade my accord done and couldn't believe the nasty-ass deep dent they got out perfect...gone.

[Solid Snake]

Anyone ever take their tank to an auto dent doctor? bet they'd have a tool to pop out the problem! I hade my accord done and couldn't believe the nasty-ass deep dent they got out perfect...gone.


They take out this big ones by drilling a hole and inserting a rod in the hole which gets welded in. Then they stick a puller on the rod and pop the dent out. The rod is then cut off and the bump left from where it was welded in is grinded down, then sanded, then painted. I doubt they would be able to do this on a gas tank from any three wheeler because of the lack of space for the right tool to pull the rod that'll pull the dent out, most likely on a gas tank they would use filler.

Also, it is true that water expands when frozen, it is the only substance that does that besides non-elemental chemical compounds specifically designed to do just that. It has to do with the arranged shape of the molecules.

[MTS]

You can try bending a steel bar to fit in the tank and push out the dent yourself, body shop's also have a tool that welds a rivit to the dent then pull's it out

[dblshockpower]

the dent doctor I went to was paintless..they have tools to get inside the doors and fenders then leverage the dent from behind...he charged me $100 for two dents on a car but if he's sucessful that's cheap compared to decals, bondo and paint.

[dreadhed]

Also, it is true that water expands when frozen, it is the only substance that does that besides non-elemental chemical compounds specifically designed to do just that. It has to do with the arranged shape of the molecules.
Yes water expands when frozen.

[willcamach]

correct me if im wrong but doesnt water boil then evaporate when heated? either way i know some people use the frozen water trick on 2 stroke pipes but say to be careful not to leave it in to long because the water will eventually freeze completly and disfigure the pipe or tank...as for dry ice i play with that stuff all the time because i run an ice cream vending business on the side and ive also put dry ice in a sealed bag never in a glass jar but i dont think it would work well for dent's the pressure seems to build enough to barely bust the plastic bag. dont think a metal tank will give that easily

[Oldshell4481]

the toilet bowl cleaner idea is really dumb, that creates an acid which wouldnt be good for your fuel system/tank.

[thedeatons]

The tool is referred to as a dent puller.... No holes are drilled to use it. You can pick up an economy one fairly cheap. You remove paint in a dime size area, then load the machine with the rod. hit a button on the machine and the rod welds itself to the metal. There is a sliding handlegrip on the bar that you slide away from the metal with force, when it reaches the end of the rod the force pulls the dent out. Then, like it's said above, you grind the rod away and flatten the space back out. This is your best, safest bet. This is what body shops use when they aren't using filler. I also talked with Mike at Vintage Motorsports today and he said this is the method he uses and will use on my tank. After it is pulled out he will use a very light coat of filler just to get the shape and flatness correct. Good filler will not crack or peel away. Read this VW article for the dent puller I mentioned above...

http://www.vwtrendsweb.com/tech/0402vwt_super/

[Solid Snake]

Ah so it welds right to it, thanks for the correction.

[trikes=fun]

oww dry ice hurts i'v been burned by it before!!!!! Never heard of that before i might do that got a quarter size ding in my tank from someelses handle bars.

[Jim mac]

isn't the dry ice trick used on cars with hail damage? You put the dry ice on the dents and the metal contracts and shrinks the ding, or pops the dings flat. never seen it done buy thats what I heard. Jim

[pomona51]

If I use the welding trick I probably want to make sure there is no gas in the tank. LOL. Thanks for all the help guys. I will let you guys know what I decide.

[monster 84r]

the meathod stated a few posts above me sounds good. in theory the dry ice should work, since metal has a memory, but the ammount of psi it would take to force out a dent would first baloon out the sides or create leaks in the seams, before it would force out a dent.

but i was just thinking of mabe trying the dry ice trick, but heat up the dent mildly with an acetylene torch while the pressure builds so that it pops out eisier. that way instead of deforming the whole tank with a ton of pressure, the dent goes back to normal and the tank is fine. of course you would have to sand down the dent so the paint doesnt melt from the torch, and then repaint afterwards.

and its true that alot of smaller shallow dents can easier be covered with a thin coat of body filler. the hot rod fabricators use it on metal bodies to get everything smoth and uniform.

[88 Turbo Coupe]

There is a suction cup method which pulls out dents. Harmless to the paint. No welding, bondo, painting or sanding needed.

[conig]

turbo coupe I have seen that thing on TV does it actually work?

[88 Turbo Coupe]

turbo coupe I have seen that thing on TV does it actually work?


I dont know if the TV one works but if you look in the yellow pages you can find an outfit that pulls dents from cars using this method. The principle seems sound.

[conig]

I have pulled larger dents with a "mission impossible" or "entrapment" style suction cup but I don;t think most dents in my gas tank would have that kind of surface area. plus the dents have creases that won;t come smooth.

I agree the theory does seem as sound as using a slide hammer attached to a rivet or tach weleded wire.

[Fox250R]

Dryice never lasts long around my house im always try to blow it up :)

[88 Turbo Coupe]

I have pulled larger dents with a "mission impossible" or "entrapment" style suction cup but I don;t think most dents in my gas tank would have that kind of surface area. plus the dents have creases that won;t come smooth.

I agree the theory does seem as sound as using a slide hammer attached to a rivet or tach weleded wire.

The slap hammer method will of course work. But you are right, you need surface area to make the suction method work right. I didn't know yu had a crease in it. Almost seems worth while to buy a dented tank and try some of these methods. But all the internal methods mentioned (freezing, dry ice, aluminium added to) you dont have any control over. No guarantee that the dent will push out. A semi eliptical shape (dent) is more strong than a flat surface (undented tank).

[Rex Karz]

This thread .......... HAR HAR HAR !

[3 weelin geezer]

Forget the toilet bowl cleaner. Use an mre heater and some water. Not really. Just cut off the bottom with a thin dremel cutoff tool, bang the dent out and get it all tig welded back together. Yeah, it seems a lot of work but it will be better than screwing it up with a shortcut.