Manifold Repair

Mopar Exhaust Systems

  1. DentalDart

    DentalDart Well-Known Member

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    So I've searched and read through different threads on repairing cast iron exhaust manifolds. I just got the matching ds hp exhaust manifold. The most anterior (front) bolt ear is cracked ever so slightly on the outer surface. I've seen people say they have had good luck "braze" fixing it also others say it can be welded but it's extremely difficult. Even saw one person say JB weld lol. Is there a clear cut best way to fix it? My uncle owns a very large welding company, but he says I'm the second person in 35yrs to ask him about cast iron welding and that it is very very difficult but he will ask around.

    I also was thinking of cleaning up the ps manifold, it has a little pitting and rust on it. Can this be done at home or is sand blasting the best way to do it? I know some of you own giant shops and can sand blast at home but that's not an option for me.

    Pics for clicks .

    Edit I'm aware of the 3 different manifolds in pictures. Car came with 68hp exhaust manifold and 72hp manifold on it, and I got the matching 68hp just yesterday. I'll try and clean all 3 up in this project.

    IMG_1086.jpg

    IMG_1085.jpg

    20190915_191931.jpg

    20190915_192013.jpg
     
    Last edited: Sep 28, 2019
  2. clifftt

    clifftt Well-Known Member

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    DD, I can’t advise you on the welding, but I cleaned mine really nice in a tall tray of cheap vinegar.
    I took a kitty litter cat box, got a few gallons of cheap vinegar at the grocery store, and let them soak for a couple of weeks. Occasionally, I would remove some vinegar and replenish with fresh vinegar. With almost no labor and under $15, they came out nice. The vinegar dissolved the rust. I shot them with a couple of coats of Eastwood’s exhaust paint. After a couple hundred miles, they still look great! You can kind of see them in this picture...

    C66D01A6-998D-44D4-8FC9-F03DD2079B9F.jpeg
     
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    • DentalDart

      DentalDart Well-Known Member

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      That looks to nice for me car.... Advice from someone else?

      Just kidding, that's a great idea, also have heard to soak them in vinegar before, or Coke (the drinking kind). Maybe this is what I will do as I have headers on my car and these aren't going back on anytime soon. Just gives me another project to do while enjoying the car, plus helps me learn something new.
       
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      • Dana67Dart

        Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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        Check out this video.



        .
         
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        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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          Nickel rod would work good to braze that.
           
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          • DentalDart

            DentalDart Well-Known Member

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            Both look good, what I'm seeing is it's going to cost more buying toolss to fix it than the manifold cost :rofl:
             
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            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              Probably.
               
            • DentalDart

              DentalDart Well-Known Member

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              Shhh! Don't tell my wife that though.
               
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              • Plymouth 65

                Plymouth 65 Floorable Deplorable

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                Nickle rod will quell the carbon in the microstructure of the cast iron from coming to the heat affected zone of the weld and eliminate/reduce micro cracking. 65'
                 
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  I think the best way.......however you weld it will be to break the ear off completely. If you don't, even after you weld it, it will continue to crack. Brazing is probably the easiest, but that Muggyweld is probably stronger. Either way, you will need to weld it all the way around, so that will mean milling the head sealing face. So there's "THAT" expense as well.
                   
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                  • DentalDart

                    DentalDart Well-Known Member

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                    I was going to ask if I should break the ear off completely, glad you thought ahead.
                     
                  • 69_340_GTS

                    69_340_GTS Well-Known Member

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                    There's a 98% chance that the sealing surfaces are warped. Even on the manifolds that are not cracked. If you put warped manifolds back on, they usually crack because cast iron isn't exactly very flexible. So any exhaust manifold you want to re-use should at least be fly-cut (milled) flat.

                    When you get the ear welded back on, the bolt hole will need reaming out and the entire face will need to be milled.

                    And no, J-B weld won't work.
                     
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                    • krazykuda

                      krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                      I burned through an exhaust manifold once while porting it and mig welded the hole closed with no problems...
                       
                    • dcl68

                      dcl68 FABO Gold Member FABO Gold Member

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                      Last edited: Sep 29, 2019
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                      • 4spdragtop

                        4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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                        I've heard good about these, thanks for the review.
                         
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                        • toolmanmike

                          toolmanmike Moderator Staff Member FABO Gold Member

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                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^This!
                           
                        • Tooljunkie

                          Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                          I broke the cast manifold on my kubota. Vertical muffler and pipe. Tagged the hoist in the shop as i backed in under it.
                          I popped it back into place and mig welded it while it was still hot. It held fine until i did the exact same thing again a month later. :BangHead:
                          So i made a new elbow,and exhaust goes downwards now. Wont happen again.

                          Think i would v out the crack with a die grinder,heat it up and fill it back in with mig.
                          Keep it hot and and cool it off slow.
                          Then true the flanges,as thats likely what cracked it to begin with. I never used gaskets on my power wagon 318. Just a smear of high temp silicone. 15 years plus since i had them off.
                           
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                          • brian6pac

                            brian6pac Well-Known Member

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                            You need to break it off also so you can clean all the rust out before you weld it.
                             
                          • MoparMike1974

                            MoparMike1974 FABO Gold Member FABO Gold Member

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                            V out the crack, drill crack stops at each end, pre-heat part then weld with nickel rod. Cover part with sand so it can cool slowly. This is the old tried and true method for cast.
                            However, like mentioned here mig can repair cast well. It really depends on if its a high stress part. The problem with a manifold is they are thin and they expand and contract all the time.
                             
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                            • DentalDart

                              DentalDart Well-Known Member

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                              Thanks! Im going to try and get those muggy sticks and take them to my uncle's shop one day.

                              Maybe they'd be able to mill it, sand blast it and powder coat it all there too. I know his company does all those things, so we will see what he says.
                               
                            • red67gts

                              red67gts FABO Gold Member FABO Gold Member

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                              then only weld about 1/4" and peen it good and wait maybe 15 min then repeat
                               
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                              • MoparMike1974

                                MoparMike1974 FABO Gold Member FABO Gold Member

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                                Why peen it? Stress relief?
                                 
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                                • red67gts

                                  red67gts FABO Gold Member FABO Gold Member

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                                  yes
                                   
                                • RustyRatRod

                                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                                  Yeah. Cast iron will crack if you look at it sideways.
                                   
                                • halfafish

                                  halfafish Damn those rabbits, and their holes! FABO Gold Member

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                                  I had some extremely rusty/nasty parts to deal with. I used a 10:1 mix of water to molasses and let the stuff soak for a few weeks. They came out very nicely, and it cost me less than a dollar.
                                   
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