Welding a Exhaust Manifold

Mopar Exhaust Systems

  1. bobscuda67

    bobscuda67 Well-Known Member

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    Hey everyone. I have a 340 right side exhaust manifold with a piece missing at the exhaust pipe bolt flange. I was wondering if it can be welded. What type of rod should you use?
    I can still bolt up a headpipe if I use a washer to span the missing section and it doesn't leak but I'd like it repaired.
     
  2. oldkimmer

    oldkimmer FABO Gold Member FABO Gold Member

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    ..............I'd braze it........kim.......
     
  3. Treblig

    Treblig FABO Gold Member FABO Gold Member

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    If you make a search on the web for "welding cast iron" you'll get many sites where someone has documented the best way. Just be sure and read a site where they talk about welding "exhaust manifolds" as they are a special case. Evidently, exhaust manifolds have a high carbon content from all the exhaust and heat that they are exposed to and this high carbon content makes them harder to weld.

    treblig
     
  4. Treblig

    Treblig FABO Gold Member FABO Gold Member

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  5. Louie70Dart

    Louie70Dart Back home in K-Town WI. Woo Hoo FABO Gold Member

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    Plus I saw something on Spike TV, the Power Block shows. About the only time they weren't tooting the chebby horn. They, Tommy?, did a weld on an exhaust manifold. Also welded an ear on a block once. Hope this helps.
     
  6. cudascott

    cudascott wish I had a Hemi

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    I have welded lots of cast iron. Just heat up the area to be welded red hot and weld with a high nickel rod and cool slowly if you let it cool too fast it will crack. The best way to cool it slowly
    is to get a tub or container that the part will fit in add about 2" of sand in the bottom of the container then as soon as the weld is complete put the part in and completely cover it with sand
    and and forget it for a while.
     
  7. Tom Swope

    Tom Swope Well-Known Member

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    Bolt an hp flange to the manifold along with the broken piece in place. Make sure the flat (gasket side) of the flange is not the side that is welded to the manifold. Thick lazer cut flanges are best and are flat on both sides unlike stamped flanges. After preparing the manifold for the welding process ( wire brushing, grinding etc.) weld the flange to the manifold and to the broken piece. Weld the flange 360 degrees around where the flange meets the manifold. Stronger than new. Works every time. The extra amount of distance this process drops the exhaust pipe ( approx. 3/8") is negligible and rarely causes an issue.
     
  8. jbc426

    jbc426 Well-Known Member

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    Use your BBQ and some briquettes to per-heat the part before welding with the correct rod, then leave the part in the BBQ to very slowly cool down as they burn out over the next couple hours.
     
  9. ntsqd

    ntsqd Well-Known Member

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    Wouldn't it be easier to get another manifold? Or is that crazy talk?
     
  10. mopar jimmie

    mopar jimmie Mopar Jimmie

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    i did this exact same repair on a drivers side 340 hp manifold , i used a flux coated brazing rod and it welded perfectly .I welded it over 15 yrs ago and its still going strong with no issues
     
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