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  • Saving a rusty exhaust manifold.

    I have an old tractor. The exhaust manifold has a threaded piece of plumbing pipe screwed into it and they are rusted together SOLID!

    I want to save the manifold if at all possible since it appears to be in really good shape aside from the rust.

    I've been trying a combination of tapping with a hammer, penetrating oils, and a hot air gun (~830°F).

    What do you recommend?

    I do have an oxyacetylene outfit available if I need to step up the heat.

  • #2
    Ordinary threaded pipe? Just cut it off close and die grind it on the inside in a couple of spots to thin it, then use a chisel to collapse it. Once you get it down to the crest of the threads it collapses easily.
    Location: Saskatoon, Saskatchewan, Canada

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    • #3
      Yep, ordinary threaded pipe.

      If I can pull that off without cracking the manifold it should be faster than what I've been doing...and getting nowhere.

      Thanks!

      Comment


      • #4
        You didn't mention what size pipe but I've reamed old fittings with a pipe reamer then just re-tapped the threads. The reamer will cut the threads loose most of the time and you can pick them out. The tap will push or breakup the rest.

        Use a drill press on dead-slow for the reamer and use a coolant. Peck at it when you start getting close. By the way, pipe reamers are tapered.

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        • #5
          Remove the manifold from the engine. Saw off the pipe as close as you can to the manifold.

          Then, use your oxy-acetylene cutting torch to burn through the pipe. If you work fast you will not harm the manifold.

          An oxy-acetylene cutting torch generally leaves cast-iron alone. The only danger you have is melting the crests of the threads if you dilly-dally with the cutting.

          If you don't believe me, play around with a piece of scrap cast-iron. You'll soon be a believer.

          Good luck!

          Orrin
          So many projects. So little time.

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          • #6
            I'd try electrolysis.

            http://www.stovebolt.com/techtips/ru..._derusting.htm

            I bought a vise that had been sitting outdoors for who knows how many years... it was rusted solid. It ended up taking the better part of a week, but eventually electrolysis not only got it free, but removed 99.9% of the rust.

            Lots of people will tell you that it's "line of sight" but I've found that it works on any exposed parts even if they're blocked by other parts. The effect is much faster in a straight line and it'll remove that rust first, but if you leave it going long enough, eventually it'll get all of the rust.

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            • #7
              I have had excellent results in similar circumstances by placing in Evaporust. It will chase rust down the threads. Electrolysis also...

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              • #8
                I've used Arcane's method several times, with univerally good results. The sawing takes but a few minutes; I use one of those plastic handles that clamps onto a hacksaw blade, but tape would work just as well. Cut until you actually see a bit of the threads. Make 2 cuts, then take a cold chisel and collapse the remainder of the pipe.

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                • #9
                  I'd agree with the electrolytic rust removal. I've gotten some incredibly rusted together crap apart by this method.

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                  • #10
                    Rust removal via electrolysis has my vote. All you need is a standard 12VDC battery charger, some washing soda (to keep the solution basic and not acidic) and some electrodes. If I can find the link I'm after, it's a pictorial story on a guy that actually did this to the entire cab of a real old truck. Every rusted bolt and screw came right out after that. It was amazing! But in the mean time this will get you started:

                    http://1bad6t.com/rust_removal.html

                    I've done this method to a Bridgeport vise and then it went from that tank to a phosphoric acid bath over night for a cheap Parkerizing effect. From there to an oven to bake for a couple of hours and I have one stunning original vise that looks like it belongs in a gunsmiths shop

                    If I find that other link I'll add it on to this post.

                    *** found it!! Your gonna love this. Check out what this guy did. He's got LOTS of pics for ya

                    http://www.bbssystem.com/manuals/Derusting_oldtruck.pdf
                    Last edited by Metalmelter; 09-09-2011, 11:33 PM.
                    "To invent you need a good imagination and a pile of junk" Thomas Edison

                    Better to have tools you don't need than to need tools you don't have

                    73's KB3BFR

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                    • #11
                      Worse comes to worse, You could allways use a pipe reamer to ream it completely out, even damageing the thread if need be, then pipe tap it.

                      Its a tapered thread, So you just have to keep taping untill you are deep enough to restore the thread (Note for larger pipe tap sizes, this can be a ****LOAD of torque, Consider not doing it with the manifold on the tractor..), since taping continiously recuts all threads deeper and deeper, ruining the crests is OK.

                      Then you just need to grind back the manifold if the pipe nipple has to screw in too deep.
                      Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                      • #12
                        Originally posted by Black_Moons
                        Worse comes to worse, You could allways use a pipe reamer to ream it completely out, even damageing the thread if need be, then pipe tap it.

                        Its a tapered thread, So you just have to keep taping untill you are deep enough to restore the thread (Note for larger pipe tap sizes, this can be a ****LOAD of torque, Consider not doing it with the manifold on the tractor..), since taping continiously recuts all threads deeper and deeper, ruining the crests is OK.

                        Then you just need to grind back the manifold if the pipe nipple has to screw in too deep.
                        Just because it had a pipe screwed into it does not guarantee that the receiving threads in the manifold are tapered.
                        James

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                        • #13
                          There is the option of trying to shrink the fitting a tad. Cut it off leaving maybe 1/2 inch sticking out, then saw from the inside towards the threads. Saw right through one side where it sticks out. Try to crush the fitting with vise grips while attempting to back it out.
                          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                          • #14
                            That's a problem I see every so often.My fix is cut it off leaving a half inch there about,then run a couple cold passes of weld around the inside of the pipe.Start out at a low amperage so you don't burn through.

                            When the weld cools it contracts and breaks the rust bond.Tack a piece of flat bar across it for a handle and twist it out.
                            I just need one more tool,just one!

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                            • #15
                              Originally posted by J. Randall
                              Just because it had a pipe screwed into it does not guarantee that the receiving threads in the manifold are tapered.
                              James
                              Sure, Iv had that problem before. But the threads where nicer tapered after I was done!

                              darryl: Not sure id want to saw through the threads, While you don't really need a whole thread, Im not sure how its gonna seal with a gap in there, unless you then use some high temp... sealant of some kind.

                              wierdscience: Very intresting approch. Im sure the intense localised heating helps break the bond too.
                              Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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