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Thread: question on welding cast iron

  1. #1

    Default question on welding cast iron

    I have a "Junk" 1947 ford flathead engine sitting on my garage floor that I grabbed for free last weekend. at some point in it's life it sat with water in the jackets and froze. it's got a crack in the oil pan rail. not an uncommon thing with these motors. It's free to me and my son and I are taking it apart for a learning experience. I wouldn't mind taking a shot at welding up the crack.

    I've heard a few different processes for welding cast iron:

    55 or 99 nickel rod
    308 stainless rod
    *insert your magic rod here* brand of cast iron magic
    tig brazing with silicon or AL. bronze rod.

    given that this is in the oil pan/cooling flow location it won't see extreme heat and the stress that caused the crack was from frozen water... so that's not an issue.

    what are your thoughts and successes with such a fix?? I'm not going to be out anything other than the cost of the rod I used and my time if it goes pare shaped. perfect practice job, and if it works that's a bonus.

    pictures to follow
    Last edited by revkev6; 01-17-2017 at 06:09 PM.
    Everlast Powertig 225LX
    Harbor Freight O/A rig
    60 gal air compressor

  2. #2


    Click image for larger version. 

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    Everlast Powertig 225LX
    Harbor Freight O/A rig
    60 gal air compressor

  3. #3


    That's the perfect thing to take a free stab at, although to truly know how it worked you'll have to build it and run it! Which aint bad bit of fun either! Only pain I see bout it is it's a between the crack fix that will rely on both sides to stick and expand at same rate. I've had probs with that kinda thing on iron motors. If it was aluminum I'd grind that whole wall out to get a hole, then I just have to stick to side and not glue 2 sides. I've often either padded all back with rod, or pad till I can get sheet onto it. Since your messing round just giving you ideas to try.


  4. #4
    Join Date
    May 2012


    One option that usually works is tapered cast iron plugs. A company called Irontite makes them. You drill, taper ream and tap holes along the crack, and screw in the plugs until they break off. You put them in so they overlap each other. I have used them even in combustion chambers and they work great. They come in different sizes, but the ones I did the most of were about about 3/16" diameter at the bottom, and maybe 5/16" at the top. Since they are cast iron, there is no issue with expansion rates. I once did a water jacket freeze crack, but it was in the valley of a V8. Probably used around 100 plugs for that job, but it was a rare block, (427 side oiler from a 67 Cobra) so it was one of those whatever it takes jobs.
    Long arc, short arc, heliarc and in-the-dark!

  5. #5


    Brazing works well.

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