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exaust manifold crack welding?

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  • exaust manifold crack welding?

    I have to weld a crack in an exaust manifold and aint sure what to use, don't know if I should stick weld or mig it, and what type of rod to use if thats the case any help would be great thanks

  • #2
    I did one that is still on the road. I ground out the crack and used an old Eutectic rod that I don't know the composition of. The second pass was with E309 stainless.

    Edit: Oh yeah, preheat and SLOW cool.
    Last edited by MAC702; 05-12-2006, 06:07 PM.

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    • #3
      Exhaust manifolds are hit and miss because all the good stuff is burned out. I just used 7018 when i did them years back. Cast or SS rod would be ideal if you want to spend the money...Bob

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      • #4
        Patience

        That is the key to weld the manifold,first you preheat till the peice stops really stinking and starts to clean up (about 350 deg) on its own
        Everthing depends on judgment ie ;material thickness ,so on age is a big thing because older cast tend to get brittle over time you can braze the peice if you want or stick weld it there are lots of good cast rods available if you choose that rouht make sure you peen between welds to releive internal stresses cover the peice in sand after or wrap it in a weld blanket and let cool slowly

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        • #5
          I would braze it...

          I have done several and I brazed them. I "V" out around the crack good and then I preheat them like they said. I then load it up with flux and have at it. I have even done one on my old 292 Ford that I cut the flange off and removed a section to adjust the angle, and then brazed it back together. That was 8 years ago...

          I dont know if it was all necessary, but I had my Dad surface off the head sealing surface to make sure I didn't warp it...

          Might be a low tech way, but worked quite well..

          Thanks!

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          • #6
            exhaust manifolds

            heat the casting to a minimum of 350F, to bake out the oils and impurities, then let it cool. The weld repair can be done hot, with pre heating and cooling slowly, or it can be done cold. Due to the small cross sections of a manifold, it can be easily welded with Ni-rod or cast rods with little pre heat or post heat, so I will go with the cold method. Build a jig to hold the pieces in the right shape, then V-groove the joint 90 degrees, leaving a small root, 1/16" to 3/32", then grind the surface of the casting to clean up the porosity about 1/4" away from the joint. Use low heat, 60 - 80 amps for a 3/32 rod, and weld stringer beads, not more than 2 - 3 inches in length. Peen the weldment between passes, and let the casting cool between passes so you can touch it with your bare hand. The more peening during cooling, the better. Avoid weaving because it contracts the edges of the groove too much and causes cracking. I've used many different types of cast rods for repair, Ni Rod, Arctec supercast 80 and 90, Arctect cast 3, Certainium alloys, and another, Cronetron 211. Cronetron 211, as put, "the cast iron problem solver', is by far the best I've encountered in the past twelve years. Any of these electrodes will work, as long as they contain a sufficent amount of nickel. You want a rod that has a good elongation, so it doesn't allow cracking before you peen. Some electrodes are designed for hot cast welding, where temps are controlled for lengths of time, and some are more forgiving. After the joint is filled, you can grind the face reinforcement off and finish the weld repair with a needle scaler to give it a 'as cast look' which also relieves stress at the same time.

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            • #7
              We used to repair a fair number of cracked manifolds for Detroit Diesel engines. I was most impressed with the Cronatron cast iron rod for weld quality and forgiveness. The rep who demonstrated the Cronatron rod was quite proud of the fact that repairs could be done without removing the manifold - and without much prep work. Obviously, no one in the shop believed him - since we were used to extensive cleanup, grinding, and preheat. The sales rep explained that his rod was coated with a special flux which effectively purged the cast as it was welded, and then proceeded to prove it. The Cronatron rod is expensive, but it works better than anything I've ever seen before.

              One piece of prep work that I always do with cast iron parts is to drill a small relief hole (about 3/16 to 1/4 inch) at each end of the crack. Drilling the ends of the crack helps to prevent extension of the crack as the cast expands and contracts during the weld process.

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              • #8
                Old methods for crack repair on Cast Iron

                We have to repair many many cast iron manifolds for both antique repair and for modern production. After years of testing, Oxy-Acet. welding using cast iron rod and the old cast iron flux, following AWS procedures for preheat and cooling, produced the best repairs for long term useage. Also spraywelding is commonly used in the marine industry as an assembly and repair tool for exhaust manifold production. 350 is warm enough to burn out oil, but if this engine ran on leaded fuel, beware of the lead salts, they can create loads of trouble if you dont preheat to 750 or 800 for an hour before hand. Cast is funny and not always the same from batch to batch, especially old stuff, take your time and dont rush it!
                -Aaron

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                • #9
                  An interesting thread with some great replys.

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