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  1. #1
    Join Date
    Nov 2007
    Location
    Appleton WI
    Posts
    59

    Default cast iron muffler

    I have a cast iron muffler on a diesel lawn tractor with a crack. I don't handle cast at work and have never dealt with it in the past. Rather than shell out $400 for a new one, I'd like to try to repair this one first. I know cast is pretty sensitive to heat change. I'm looking for some advice on repairing this thing. It's not in a high stress area. I have a cheap little HF stick/tig here, but I have a lincoln square wave tig that will also do stick. Everything I do is mig, tig, or sub arc, so stick is bit of a gray area for me. I also read that brazing is a possibility? Any info is greatly appreciated. Thank you!

    Pete

  2. #2
    Join Date
    Dec 2009
    Location
    Williams Lake, British Columbia
    Posts
    722

    Default

    I would try brazing. Clean good and braze at her.

  3. #3
    Join Date
    May 2008
    Location
    Austin Tx.
    Posts
    101

    Wink

    I welded some cast iron a while back by taking a nickel stick rod and cleaning off the black flux coating by hammering on it and then using a scotch brite pad and then tig- brazing.
    It actually worked pretty good.
    You have to clean the crack real good with a wire wheel.
    Might give it a try.

  4. #4
    Join Date
    Apr 2010
    Posts
    1

    Default

    nickel rod worked good for me, the few times i have welded exhaust manifold cracks

    an important part of fixing a crack on cast iron is to drill relief holes on the end of the crack on both sides otherwise you could end up chasing the crack around and/or breaking the piece apart.

  5. #5
    Join Date
    Feb 2010
    Location
    Houston, Tx.
    Posts
    378

    Default

    You can stick weld it. Ni-99 rod will do just fine unless you plan on machining the weld afterwards. You either weld cast iron hot or cold no in betweens. To weld it hot, you preheat the entire piece to a certain temp, weld and leave in post heat, then only drop the temp a certain amount per hour until at ambient. Most people don't have the facilities for this. To weld it cold run short beads , 1" or so, letting the welds cool to room temp between welds. Cast iron wants to crack when the temp is changed drastically in one area of the casting. I've had good luck with the cold stitch welding technique, just don't apply too much heat for too long.

  6. #6
    Join Date
    Feb 2007
    Location
    West Farmington, OH
    Posts
    746

    Default

    I've done as both fendermender and Wolfgar have suggested with great success. I welded some cast arms on our bandsaw 6 years ago and still going strong using nickel rod and TIG welding and have repaired numerous cast iron pieces by drilling holes at each end of the crack.

    Good luck with your repair
    Blondie (Owner C & S Automotive)

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