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My 1981 CM400C came with a bid dent on the right side of the tank. PO said it fell over and hit something. The tank isn't punctured, but it's unsightly. Any advise on how to pop it back out?
Thanks,
Tom
 

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Send pictures please
 

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Air compressor line into the filler hole with a rag around it to seal it, and petcock turned off. It May or may not do something. Depends on just how bad the dent is, if it has alot of creases to it then it likely won't pop out. Have to weld rods on it to pull out with slide hammer. Or just hunt down another tank if you don't like body work.
 

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Do you want to repaint or keep it origional? .. I have tried multiple ways (dry ice, compressed air, hot glue)... with a repaint you are up for pretty much anything (except drill)..
paying a pro to do a "paintless repair".. is your best bet for best results..
 

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The 'pros' use a steel bar to lever the dents out. The bar is bent in a fashon to get behind the dent. Then it uses the gas filler as the folcrum. It may take a helper. Let us know how it comes out.
 

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Air compressor line into the filler hole with a rag around it to seal it, and petcock turned off. It May or may not do something. Depends on just how bad the dent is, if it has alot of creases to it then it likely won't pop out. Have to weld rods on it to pull out with slide hammer. Or just hunt down another tank if you don't like body work.
Put enough air in it and it may push the floor of the tank down and both sides out at the same time, I've seen it happen several times.
 
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I was tempted to say put a dent in the other side and start a trend. But it looks like you got better advice here . . .
 
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Watch a few videos on youtube with different techniques. You can pull or push it out, paintless repair or not. Many times you can glue and pull it out without damaging the paint. Use as little filler as possible.
 

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don't know if the guy was full of you know, but he told me to fill it with water and freeze it. the ice will push the dent out.
 

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I'm no expert but anything that expands can push out a dent. From what I've seen on youtube, when it's not controlled it may damage the tank. I think it's better to pull or push it out with a tool by hand.
 

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^^^^+1^^^^^
Post picks.. if you are set on using "compressed air".. try a "bladder".. it will help focus the pressure but remember it will also be pushing on the opposite side of the dent. You also have to consider the condition of your tank, the bottom seam after years of condensation may not be in the greatest condition ..
Again, tell us what your intentions are with this tank.. it will help clarify any advice that can be offered.
 

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Heat it with a heat gun and see if you can press it out. You’ll have to get creative obviously on how to press it, but perhaps the bent end of a small crow bar. Maybe wrap the end with a thick rag to help spread out where you are applying force. Hopefully you’ll be able to get out a lot of it.


Sent from my iPhone using Tapatalk
 

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+1 on looking for another tank if you'd rather ride dent-free. But I'd say look around on ebay at some of the other dented tanks to get a feel for what people are asking for them. You may sell it quickly if the price is right and offset the cost of a nice tank.
 

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This tank could be saved for $$$. First it would need to be hot tanked at a radiator shop or equivalent. This will make it safe to weld on. Then the dents could be pulled out with a stud welder (see link). It will still be creased around edges of the dent. These could be hammered in and smoothed with bondo. The big cost would be the stud welder, but if yu had access to the equipment it would be feasible. Otherwise this tank is not economically feasible for repair. https://www.eastwood.com/stud-welder-dent-pulling-system.html
 

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Gotta agree ... no chance in saving that paint... I have used stud welders on tanks with mixed results... the spotwelds create a "hard point" on the sheet metal of the tank... then when "pulled" back to its origional position it creates micro "cracks" around the hard weld.. basically making thin metal around the spot weld... not a major issue.. sweat/brazen around this when ur done will eliminate leaks.
Sweating/ soldering a contact point to be pulled will also help as it is only "secured" to the surface as apposed to creating a hardened spot..,
F**k it.. find another tank.. but take the tank you have and give it a shot in trying to repair it.. try the least "intrusive" process first.. then progress to more agressive.. worst case ... you learn something
Keep us posted... I'm curious how things work out and how you progress..
hell.. spend a couple hours searching "youtube".. give something a try, maybe you can pass on what you learned to a young kid in your neighborhood that can learn from you...
.. he maybe the guy passing on info when he has someone asking him questions in the future ..
 

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I was wondering if it'd be feasable to just drill a hole and saber saw the dented bit out, hammer the dent out on a shot bag and weld the piece back in place. Some filler and paint... And Bob becomes your uncle!

Kinda like the cut/flip/weld knee dent routine.
 
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