Any tips for welding something you can't see?

Does anyone here have any tips for welding in places that you can't see?
I'm trying to weld up some exhaust pipe on my truck, and can't see the top
of the pipe I'm trying to weld together.
Thanks!
Jeremy
--
It has become appallingly obvious that our technology has exceeded our
humanity.
-Albert Einstein
Reply to
Jeremy Chavers
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Are you sure you are not a weldment designer in your day job. It really helps if you can remove, weld , then reinstall. At least see if you can drop the pipe down off its hangers onto some temporary wire ties. If it is stick you can actually bend the rods. Some people don't know that. If you can sit a pocket mirror in the right place it helps. the mirror trick will not likely work overhead. Some mig nozzles are more bendable than others. If you have spare parts you can bend a custom gooseneck. Worst case is to cut a big hole in the bottom part of the pipe then weld up the upper section from the inside. After welding that up make a patch to cover the hole on the underside. Randy
Reply to
Randy Zimmerman
The R&R option would turn a 10 minute job into a 3-4 hour job. I'm trying to repair the Y-pipe on my '79 GMC 4x4, and removing it requires removing the front driveshaft and the rest of the entire exhaust system. I've actually gotten it pretty much done, there's just a small section at the very top that I couldn't get (MIG gun was hitting the bottom of the torque converter), and it's going to have to stay that way 'till I get my headers on.
Thanks!
Jeremy
Reply to
Jeremy Chavers
I made up a mirror out of a 3x5 gold mirrorized filter with a plastic cover lens to eliminate the pitting associated with glass. Then bend some 3/32 6011, set welder at straight polarity, turn it down, and think "backwards"
Reply to
Barnronhart
Except bending some 3/32 6011 won't do me any good with my MIG gun...... ;-)
Reply to
Jeremy Chavers
Is there any chance you could reach the spot with a small oxyacetylene torch?
JC> The R&R option would turn a 10 minute job into a 3-4 hour job. I'm trying JC> to repair the Y-pipe on my '79 GMC 4x4, and removing it requires removing JC> the front driveshaft and the rest of the entire exhaust system. I've JC> actually gotten it pretty much done, there's just a small section at the JC> very top that I couldn't get (MIG gun was hitting the bottom of the torque JC> converter), and it's going to have to stay that way 'till I get my headers JC> on.
JC> Thanks!
JC> Jeremy
Reply to
Ole-Hjalmar Kristensen
If you want to keep it down to a 10 minute job why dont you plug the remaining small section at the top with muffler gum?
ive used it and it holds good in high pressure ares. fixed a 1 inch gash which was 2 feet away from where the exhaust manifold mates to the block.
will take you 5 min. if it ever blows you can always revert to the full blown job.
the other idea i thought of was to wrap some thin sheet metal around this pipe and weld where the ends meet at the bottom where you can see. the metal will cover the exposed hole at the top.if the pipe here is not completely clyindrical you might want to add some muffler gum as a sealer.
Sam
Reply to
Sam
dare I post " JB Weld" to seal the rest
Reply to
Richard
Jeremy, When welding pipe which is positioned such that I am unable to see a portion of the joint I use one of two techniques. The first involves cutting open up a "window" in the pipe so that I can fuse the walls of the problem area by welding "through" the pipe(ie. welding the inside of the pipe to seal the outside. Then replace the window cutout and weld it back in its place. Grind to suit. The second technique is to use a "slip flange" which allows an easy inside fillet weld that seals positively and is easy to make in position. This second method assumes that you have room for flanges (which you can make for an exhaust system) and the second piece can be flanged on the bench and joined to the other flange in position. Tim
Reply to
taik
I don't know what a slip flange is. I'm imagining a piece of larger tube cut in half to fit over the break. Can you describe it?
Reply to
Zorro
To make the slip flange, go down to the auto parts store a buy any exhaust flange gasket for the tubing size matching that of your exhaust. Use the gasket as a template to cut the shape and holes into a piece of 1/4" plate steel- make two of course. Slip the flange over the pipe such that 1/8" of flange overhangs the pipe. You now have a weld you can see. Align the second flange and tack it to keep the alignment. Weld everything inside and out that you can see and finish the bolt up using the gasket you bought."Zorro"
Reply to
taik
Oh I get it. He has to cut the pipe in two to install & weld it. Pretty snazzy if he can flex the cut pipe. :^) With that thought, he could just buy two flanges and a gasket, cut the pipe, flex/muscle it into position for welding and then bolt it together. That would be my choice since I don't have stock that size to fabricate from, don't have the cutting skills(tools) to make it other than making it a half day job on the flange alone. If the pipe won't flex, he will be SOL since he probably won't know till it's cut in two.
Reply to
Zorro

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