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  • Cast iron welding

    Trying to fix crack in early 70s exhaust manifold. It is bad cast. Tried in rod stick. Pure ni tig. Mild steel stick mig but it wants to separate. Always has a line on the edge that is not fused. Not an amateur. Taught at local 458 for years but this is kicking my butt. Heated it peened it but the non fusion is still there. Don't really want to go brass. Any help?

  • #2
    Why would you not want to go brass, Ive been welding up exhaust manifolds for 25 plus years with good success, well over 100 of them throughout the years.

    However, you can usually buy a new one cheaper than I can repair one for, so I only repair hard to find ones now days.

    You need to get it bolted to a plate to keep it straight, prep the joint, put it in the oven and bring the temp up to about 450 F., braze it, peen it, put it back in the oven and bring it up to 450 for about 10 min., take it out and wrap in fiberglass blankets and it should still be warm when you take it out 8-10 hrs later.

    I then put it on my belt sander to face it off, if you dont, it will crack when bolting it onto the head.
    Cost approximately $ 150.00

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    • #3
      Cast iron welding

      I tell you what I've done in the past with some cast parts I've repaired, probably not nearly as experienced as PW is, but here goes...

      Prep the weld site. I like to use a gouging rod, like "metal mover" or "Electra" from Nassau/Rockmount. I think the gouging helps burn some crud out of the base metal.

      Then I get a good fire going in my fire pit and cook some hotdogs.

      As soon as the hot dogs are done, I toss the cast part into the fire.

      Then I eat the hotdogs.

      As soon as I'm done eating, I pull the now most likely about to melt through the work bench red hot piece out of the fire and get it in place in whatever fixture I've managed to come up with to hold the hot piece of cast iron. Brush the weld site good.

      Then I TIG braze it using aluminum bronze, on AC with the balance turned up to around 80-90 percent EN, the freq at around 100. Seems to work pretty well for me in the past. Try and melt as little of the base metal as possible.

      When I'm done brazing it, I toss it back in the now smoldering fire and let it ride it out until morning. Take it out, brush it off and clean it up.

      So far, so good on my cast repairs using this highly scientific method.

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      • #4
        Ryan Jones, Aluminum Bronze, are you sure you don't mean Silicon Bronze.

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        • #5
          Originally posted by ryanjones2150 View Post
          I tell you what I've done in the past with some cast parts I've repaired, probably not nearly as experienced as PW is, but here goes...

          Prep the weld site. I like to use a gouging rod, like "metal mover" or "Electra" from Nassau/Rockmount. I think the gouging helps burn some crud out of the base metal.

          Then I get a good fire going in my fire pit and cook some hotdogs.

          As soon as the hot dogs are done, I toss the cast part into the fire.

          Then I eat the hotdogs.

          As soon as I'm done eating, I pull the now most likely about to melt through the work bench red hot piece out of the fire and get it in place in whatever fixture I've managed to come up with to hold the hot piece of cast iron. Brush the weld site good.

          Then I TIG braze it using aluminum bronze, on AC with the balance turned up to around 80-90 percent EN, the freq at around 100. Seems to work pretty well for me in the past. Try and melt as little of the base metal as possible.

          When I'm done brazing it, I toss it back in the now smoldering fire and let it ride it out until morning. Take it out, brush it off and clean it up.

          So far, so good on my cast repairs using this highly scientific method.
          How would you do this if you weren't hungry for hot dogs Well written and fun to read.
          Richard
          West coast of Florida

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          • #6
            Cast iron welding

            As a general rule, I never attempt to repair cast iron without a stomach full of amazing artery clogging hotdogs and all the fixins....

            PW, no I meant aluminum bronze. I find it to be stronger, it flows like honey when you have your machine set right and the cleaning action of the AC seems to help clear out the crud in the cast iron. Honesty, the hardest part of it, for me at least, is getting the puddle started without puddling the cast with it. But once you get a puddle going, it's quit nice to use. The last project I repaired was a bench vice I broke in half. Snapped the jaw clean off of that sucker. Performed my repair process, hotdogs included, then whomped on it with a hammer to see if it would hold. Still going. I'll run out to the shop in the morning and put up a couple of pics up of it.

            Tig man, my suggestion is aluminum bronze. Get a hand full from your LWS and run some practice beads. Anyone else have a suggestion that might help him out?

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            • #7
              Forgot all about this one...

              Busted that jaw clean off the shaft and TIG brazed it back on with aluminum bronze. First I gouged it with a cutting rod (trying to grind as little as possible) then I heated that sucker up and brazed it back on. Built the bead up over flush and used a flap disc to bring it back down in size to fit right.
              Attached Files
              Last edited by ryanjones2150; 06-14-2015, 06:41 PM.

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              • #8
                I just watched a you tube video aluminum bronze verse silicon bronze, The guy doing the video said silicon bronze was for joining dissimilar metals such as stainless to other metals.
                So I gave up watching, the only thing I use on stainless is silver solder and stainless.

                Brass does not stick to stainless very well.

                I guess I will have to do a little more searching on aluminum Bronze.

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                • #9
                  Cast iron welding

                  I think saw that same video. A guy that keeps air-quoting "weld"? I've never heard that aluminum bronze is used for joining dissimilar metals, but that doesn't mean he's wrong. I highly doubt I would try to use it for stainless, mostly because I don't see it as necessary since I have plenty of stainless rod that seems to work fine.

                  I've used it to join mild steel and for cast iron repairs and have had good luck with it. I have used silicon bronze as well, mostly for thin steel like auto body fab on a drag car.

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                  • #10
                    He actually said silicon Bronze can be used on stainless not aluminum Bronze, when I heard that I realized he didnt know what he was talking about and quit watching.

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                    • #11
                      In my early, lower-tech days I managed to successfully weld a couple of exhaust manifolds with a Sears buzz-box and nickel alloy stick rod. The weld beads had good adhesion to the sides of the joint at the time. Many years and tens of thousands of miles later I had a chance to look at them again. The beads had peeled away from the top part of the vee-ed out joint, and looked like a length of clothesline lying in the bottom of the groove. Yet somehow the joint had remained sealed at the root of the joint; no leaks.

                      As I recall the technique, after gouging the cracks (side grinder, finishing with a rotary file to clear any carborundum), pre-heat and re-clean any glop that has been sweated to the surface, and surround as much of the part as possible with fire-brick to retain heat. Then weld 1/4" at a time, peening in between these very short runs. Slow-cool the part while wrapped with asbestos cloth. Re-surface the mounting face with a big belt-grinder. Celebrate with hotdogs and suds.

                      Nowdays I throw away the old iron manifolds and fabricate tube headers.

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                      • #12
                        Cast iron welding

                        That vise I repaired cost around $100 on eBay after shipping. It's an import (of course), but a handy little sucker that's around 25 years old. I have three other vices in the shop. It just pissed me off to be honest about it. I ended up spending just about what a new one cost to fix this one. Not counting the cost of the hot dogs.

                        I made a video of the repair, just never got around to putting it up on YouTube. Making videos like that is a lot of work by yourself in case you've never made one. Unfortunately I wasn't able to get video of the part when I pulled the piece out of the fire, laid on the work bench, the tack welds all came loose, I attempted to pick the red hot metal up with my welding gloves padded with fireman's gloves, which promptly burst into flames and set the fire alarm system off in the shop. It was a gong show to say the least and I wish I had video of it. I would totally share it with you guys too.

                        My old repaired one is still going and the new one is sitting in the box under one of the work benches. I doubt I'll use it to flatten the ends of 1 1/4", 11ga stainless pipe ever again. Using a cheater pipe to tighten a vise is probably not a good plan.

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                        • #13
                          Originally posted by ryanjones
                          Using a cheater pipe to tighten a vise is probably not a good plan.
                          Using a Chinese cast iron vise as an anvil isn't a swell idea either.

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