Has anyone used the heat and compressed air method of removing dents? How much air pressure would be a good starting point?
I don't think using compressed air for that is a feasible method, for several reasons. Either the dent puller mentioned in the above post....or heating the dent and shrinking it with a wet rag might help. Ray
I used to build my expansion chambers for my 2 stroke race bikes. Every once in a while a pipe would get smashed or dented. I have used air and heat. A rubber pipe plug on one end and I made up a plug with a Shrader valve. You only need a little heat, not cherry red or you can blow a hole or cause a bulge. Depending on the dent, mild dent I would start at 15 to 20 lbs. I have used much more ( 50)but I didn't feel safe . Heat at the crease. And wait a little before more air and heat. I made the pipes with 20ga and used a .000 welding tip I used a .00 for dent repair. An auto header is thick so maybe a 1 or .0 tip. Take you time and don't hurry. Posted using the Full Custom H.A.M.B. App
Well, I'm not an engineer by trade...so my opinions are intuitive. That disclaimer made, I think it would take considerable psi (guessing 100 or more) to 'push' the dent, the smaller the dent the more psi required, I believe. So, how do you propose to seal the header tube to contain compressed air? How do you control the air pressure....when the dent 'moves' to prevent it stretching outward? How do you prevent it from blowing up? These are just some considerations that come to mind. You don't have to accept, or even like, my opinion. But I offered it because you asked. I may be incorrect, but I'd rather error on the side of caution with compressed air in a sheet metal tube. Too much like a pipe bomb to suit me. Ray
Make up a mandrel the ID of the pipe and pull that through the dented portion. Applying heat at the dent would help.
This. Especially since you said they were slip together headers and can work one tube at a time. It's the correct term for what most would call a tire valve or air valve, used to inflate your tires. It's the nipple you put the hose on. (Hey, that sounds kinda kinky, not that there's anything wrong with that.)
It only takes 15 to 20 psi to push the dents out. I cap the collector ends and bolt both headers together with a gasket between them. One of the caps on the collector end has a air chuck with regulator. Use just enough heat and the dent will come right out. To much and it can bulge or blow out, just keep your face away from it. I have never had one blow out yet and I have done quit a few of them. This is pretty common repair on dirt bikes. joe
I can regulate the air pressure on the compressor and use a air hose fitting. I'll try it out and see what happens. Posted using the Full Custom H.A.M.B. App!
This sounds logical to me, having never done it. I've always just cut out the damaged area and T.I.G welded in a new section. It may sound like a lot of work, but I always have tubing and mandrel bends on hand and I can do it really fast. I have heard of guys putting water in the tube and freezing it with good results, but that seems risky to me (tube splitting)? Has anyone here used the freezing method? Posted using the Full Custom H.A.M.B. App!
By golly, I never thought that 15-20 psi would do it. I also was assuming above a 100psi. I learned something already this year. LOL My idea was to use a steel ball that would just roll into the tube, then tap around the dent, letting the inertia push the dent out. Like hammering off dolly!
The term for a valve that is in your car tire is Shrader valve Posted using the Full Custom H.A.M.B. App
I used the water/freeze method on the zoomies on the Avanti. Got a deep dent and just added some water and tipped it so the water was sitting where the dent was. Friend had a chest style freezer and in it went overnight. Next morning no dent and no damage. Let it thaw and it was as good as new. I think I have pictures of the before and after. Much safer than compressed air. Just saying.
I guess if you leave space in the tube for expansion , the water will expand along the length of the tube instead of splitting the tube. Posted using the Full Custom H.A.M.B. App!
I do it all of the time. It also works good on gas tanks or anything else you can compress air in. Posted using the Full Custom H.A.M.B. App!
I used the screw and blow torch method screw in the dent then red hot and pull out with a pair of pliers . then weld the hole up from the screw , if it was real bad and could get with my steel rods I would work from the inside out , if it was real bad replacing the section often had to do .
I have repaired a lot of motorcycle exhaust pipes by drilling a hole in the back side opposite the dent then inserting a drift punch in the hole and knocking the dent out from the back. After the dent is out just weld up the hole.
A single pipe would not be as bad as far as sealing it as say a 4 tube header with a collector. It could be done but I would not do it my self. I have use d dent puller to remove dents from a header, that was before the day of the welded stud, drilled a hole and screwed that bugger in then give it a yank. Weld the hole shut and your done-ish.
I ended up drilling a hole through the backside of the dent and tapping it out with a punch. The dent was small, about an inch square but with sharp crease. Turned out great. Brazed the hole I drilled and called it done. Thanks for the ideas. Randy Posted using the Full Custom H.A.M.B. App!
#30 ball bearing, Prestone and a rag. At the most 20 psi, we just used a rag stuffed in the collector and rags stuffed in the primarys, heated the spot and applied air. A couple of trial hits with air and the dents come out.
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