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Cast aluminum repair Part 2

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  • Cast aluminum repair Part 2

    ​ I am a proponent of preheating my parts.

    It does two things, it burns off and out-gases some of the impurities and secondly I don't have to wait as long for the part to get up to temperature. I use this hot plate for small parts and it can't heat anything over 200 degrees. If you decide to use the heating coil type for "nice" parts, remember to put a small plate of aluminum between the coil and the finished part. I don't like the idea of red hot steel being in contact with finished aluminum.

    Click image for larger version

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    I have a box fan in the window and I vent the garage door while welding. This repair emitted a little fume but wasn't as bad as I thought.

    I normally run 3/32" tungsten with a standard collet body and a #6 cup. It's simple and allows enough coverage for exterior joints but is small enough to get into tight spots. If there's anything really deep that a ceramic cup blocks the view, use a pyrex cup when welding into corners.
    Straight argon, around 15 CFH, 5356 1/16" filler. I don't ground directly to parts but I will place a thin aluminum plate down to isolate the aluminum part that is being welded from the steel table surface.

    Strike arc. If the arc is relatively stable with no cloud of fume and the material isn't turning into a powdery hole, the quality of the casting is "ok".

    With oil saturated castings, there will be black soot and "pepper" no matter how CLEAN you think you got it. Castings have voids, tiny voids that will trap oil in them when its hot (open) and once cooled are closed, trapping the oil inside.

    Use the arc to draw out the contaminants.
    If there is a lot of contaminants. STOP and wire brush. Most contamination must be REMOVED not burned away!

    Approaching melting temperature draws more contaminates out of the voids (This also helps identify where the damage is located under the hood).

    Move along the entire crack slowly to release the impurities. DO NOT AD FILLER. Getting the part up to temp is part of this process. Heating AND cleaning. As the part gets closer to "welding" temperature adjust heat to close up the voids AUTOGENOUSLY. If there are too many contaminants it will key hole and you'll see the impurities remain in the keyhole. If the part is clean enough the keyhole should allow the contaminants to rise to the surface and can be removed by brushing.

    Generally thicker material will require the use of a burr-bit or rotary file to remove the heavily contaminated pockets (voids). This oil pan is about .125" thick so using the arc to draw out impurities and removing them from the surface with a (stainless) wire brush was adequate.

    Here is the Before on the LEFT, During (cleaning stage) CENTER and After with the weld metal deposited on the RIGHT

    ​​ ​​ Click image for larger version

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    Once the majority of the contaminants were removed and coalescence was achieved over the entire repair I added filler watching the toes fo the weld puddle carefully for any signs of cracks or fissures that I had missed. The pan has cracks all over the inside surface so watching for sooty voids was evident.
    Building up the inside repair with enough material to allow a hot pass on the outside without burning thru (creating a porous surface that could render the entire repair useless) was avoided.

    Once the inside weld was complete I moved to the outside.

    Again, strike arc and move along the crack, pulling any contaminates to the surface and removing with a wire brush.
    Once coalescence was achieved over the entire repair I welded it up.

    I made a second pass around the first to ensure no voids were present and filled the center. Done.

    Click image for larger version

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    ​​


    I wanted to share this to deter anyone that might be considering using JB Weld on their next cast aluminum oil pan repair.

    and

    How'd that old thread go,"Why buy it for a dollar when you can make it for a 100" ​​
    Last edited by Electric4Life; 02-04-2020, 01:52 PM.

  • #2
    Dang. I wish the pics came out for me.

    Comment


    • #3
      The forum must’ve realigned. Earlier the pictures wouldn’t show for me either, now they do.

      Looks like you got it handled pretty well.

      Comment


      • #4
        Yep. Pics coming through now!

        Comment


        • #5
          Thanks for the tutorial.

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