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  • I'm guessing this is a bad idea, but hear this

    So I have a broken bolt in the valve head of my jeep. Unfortunately nothing is protruding to weld a nut on.

    on another forum a guy suggested with oxy torch or welder, hold the tip on the welder on the bolt until it's cherry red. Whaaaaa?

    Is this as great way to ruin your machine or get electrocuted? I've never heard of such a thing, wouldn't the tip fuse to the bolt?Click image for larger version  Name:	20190127_135152.jpg Views:	0 Size:	51.2 KB ID:	703550

  • #2
    Originally posted by HOBARTxj View Post
    So I have a broken bolt in the valve head of my jeep. Unfortunately nothing is protruding to weld a nut on.

    on another forum a guy suggested with oxy torch or welder, hold the tip on the welder on the bolt until it's cherry red. Whaaaaa?

    Is this as great way to ruin your machine or get electrocuted? I've never heard of such a thing, wouldn't the tip fuse to the bolt?Click image for larger version Name:	20190127_135152.jpg Views:	0 Size:	51.2 KB ID:	703550
    Do a search on "Removing Broken Bolt",at the top of this page, then come back with questions, after reading, do not use friends advice.

    Comment


    • #3
      First question is why is the bolt broken? Is it seized so that whatever method you use is also going to have to fight a seized thread? Or should it come relatively easy once you have a method to turn it?

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      • #4
        I'm uncertain of why it's broken, its a used rebuilt motor. If I had to guess they broke it pulling the motor, but I don't know.

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        • #5
          Exhaust manifold bolt/stud???

          Dale
          Lives his life vicariously through his own self.

          Comment


          • #6
            So, the $64 dollar question is going to be, what are you going to do to remove it?

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            • #7
              Is this a steel stud in an aluminum head?

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              • #8
                Start with the LH drill bit, then the broken bolt extractor in the hole it makes. If neither of those work, use a nut big enough to get your welding rod into the middle of, but small enough where the weld won't join the bolt to the head when you weld the nut to the broken bolt face.

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                • #9
                  Originally posted by MAC702 View Post
                  Start with the LH drill bit, then the broken bolt extractor in the hole it makes. If neither of those work, use a nut big enough to get your welding rod into the middle of, but small enough where the weld won't join the bolt to the head when you weld the nut to the broken bolt face.
                  AND, put a thin cardboard washer under the nut. This will help by insulating the nut at first, and will burn up, and leave a space that will prevent the nut seizing against the casting when it cools.

                  Comment


                  • #10
                    Originally posted by HOBARTxj View Post
                    So I have a broken bolt in the valve head of my jeep. Unfortunately nothing is protruding to weld a nut on.

                    on another forum a guy suggested with oxy torch or welder, hold the tip on the welder on the bolt until it's cherry red. Whaaaaa?

                    Is this as great way to ruin your machine or get electrocuted? I've never heard of such a thing, wouldn't the tip fuse to the bolt?Click image for larger version Name:	20190127_135152.jpg Views:	0 Size:	51.2 KB ID:	703550
                    Somewhere between the world of magic and scientific fact is removal of that broken bolt. The magic is the welder who understands the science. The science is understanding the condition know as "Up set". Upset is the knowledge that steel when heated will expand In all directions, and contract on cooling in all directions. The up set condition is present when expansion is restrained. On cooling the item will still contract.

                    Simple terms, if the bolt is heated enough to expand, restrained in doing so by the casting, on cooling it will contract in size becoming smaller, the bond will loosen. Magic.

                    The question then becomes, how does the magician accomplish that task? I could offer up a few different ways of doing so, including the way I'd do it. But that would mean giving away the secrets of the magician. What's important to the trick however is the science behind it.

                    So...did you manage to remove it?

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                    • #11
                      I think I understand the concept. First photo is three sheared off grade 8 bolts in a transmission output flange. If looking closely it can be seen the yellow circled stud has been drilled with two left handed carbide twist drills and not much gained. The second photo shows the same flange after the thoroughly stuck fasteners were removed by the procedure mentioned prior. The third photo shows a couple of the extracted fasteners once removed from the flange. Fourth photo shows new fasteners run in the holes after chasing the threads to remove any possible fouling or clutter.

                      Pretty certain if I can do it almost anybody else can too.
                      Thanks for reading/listening.

                      Antique Hobart Engine Drive Lover X5

                      Comment


                      • #12
                        Yup, that's it in a nut shell. The secret is out now.
                        You mentioned grade 8 fasteners. Not to be a boar with the science part, but carbon content changes the temperature required for expansion. I'm sure a few other elements that typically go with higher carbon anything as well but, mostly carbon content.

                        Buddy mentioned about torch heating it red hot and letting it cool...small nail big hammer?
                        A focused arc from GTAW could do the same thing? Not over thinking it, a AC buzz box and a large diameter electrode stub shorted to the top makes a heating circuit.

                        Some guys will use a small E7014 or a small stainless rod, held perpendicular, drop building on drop and slag filling the threads as you build up to tack the nut, but it's really heating to cause expansion, upset and contraction when cooled. The slag breaks away as the stud is extracted. The rod is the yolk and slag the white around it. If you don't think you have that control, slip a short copper pipe tube into the hole to protect the threads.

                        If it doesn't work, ask why? Chances are, to much current blasting metal everywhere? Long arc lengths blasting metal everywhere? The wrong choice of rod for what's trying to be controlled in doing the job?
                        Even when broken off flush, maybe the guy doing it fills the nut before heating the broken stud. Quench makes that bond brittle and weak. Snap, time for another nut.

                        https://www.youtube.com/watch?v=YJElT9xK3bk

                        Thanks for the reply and pictures. On occasion, just drilling a small hole thins things out enough to reduce the need for higher heat volume if that makes sense? As well sending the heat deeper as it will get hotter filling a hole. But you got it, pictures to prove it.

                        Comment


                        • #13
                          just weld multiple nuts to it. first obviously needs to be smaller so just fill the middle of that nut with weld and don't worry much about melting that nut just make sure it's on there good. then weld whatever size nut you want on to the first and you should have enough clearance. alternatively you could try welding a bolt to it. either way the heat from welding should help the broken bolt release
                          Last edited by Andy578; 01-31-2019, 08:07 PM.

                          Comment


                          • #14
                            Originally posted by oldguyfrom56 View Post

                            Somewhere between the world of magic and scientific fact is removal of that broken bolt. The magic is the welder who understands the science. The science is understanding the condition know as "Up set". Upset is the knowledge that steel when heated will expand In all directions, and contract on cooling in all directions. The up set condition is present when expansion is restrained. On cooling the item will still contract.

                            Simple terms, if the bolt is heated enough to expand, restrained in doing so by the casting, on cooling it will contract in size becoming smaller, the bond will loosen. Magic.

                            The question then becomes, how does the magician accomplish that task? I could offer up a few different ways of doing so, including the way I'd do it. But that would mean giving away the secrets of the magician. What's important to the trick however is the science behind it.

                            So...did you manage to remove it?
                            Yes, but not from welding. I boogered up drilling through, was able to gave a friend chase remaining threads to get a new stud in.

                            I did however free a broken bolt on the harmonic balancer while almost turning the nut into a molten blob.
                            you never hear many talk of the light saber of doom protruding from a torch your not well focused on lol.

                            Comment


                            • #15
                              Originally posted by HOBARTxj View Post

                              Yes, but not from welding. I boogered up drilling through, was able to gave a friend chase remaining threads to get a new stud in.

                              I did however free a broken bolt on the harmonic balancer while almost turning the nut into a molten blob.
                              you never hear many talk of the light saber of doom protruding from a torch your not well focused on lol.
                              Well you got it out. That was after all the end goal so call it a success. I guess in retrospect, you learned enough to do it molten blob or other wise...winning!

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