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Supercharger Casting Repair

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  • Supercharger Casting Repair

    An friend and associate just purchased a used supercharger for his 15 year old Mustang, which he keeps in the garage and drives for special occasions. The super charger itself was in good shape, but when the previous owners engine failed something must have hit the drain plug boss on the bottom casting of the supercharger and cracked it. The first three pictures show the dent in the casting and some of the cracks that were present.

    An friend and associate just purchased a used supercharger for his 15 year old Mustang, which he keeps in the garage and drives for special occasions. The super charger itself was in good shape, but when the previous owners engine failed something must have hit the drain plug boss on the bottom casting of the supercharger and cracked it. The first three pictures show the dent in the casting and some of the cracks that were present.

    Click image for larger version  Name:	1. Cracked Casting 1.jpg Views:	1 Size:	110.0 KB ID:	702894

    Click image for larger version  Name:	2. Cracked Casting 2.jpg Views:	1 Size:	102.8 KB ID:	702895

    Click image for larger version  Name:	3. Cracked Casting 3.jpg Views:	1 Size:	92.9 KB ID:	702896

    New castings are no longer available from Ford, so he asked me to weld it up. The first question is what Aluminum alloy was the casting made of. The casting was very smooth and there were what I believe might be ejector pin locators, which would indicate that it was die cast. Usually the ejector pins are 1/8 or 1/4 inch, but these were larger so I wasn't sure.

    4. Ejector Pins ?

    Click image for larger version  Name:	4. Ejector Pins.jpg Views:	1 Size:	88.8 KB ID:	702897

    The most common alloy for die cast Aluminum is 380. To confirm the alloy my friend brought it to a metal scrap yard and had them shoot it with their X-ray gun. The concentration of the various elements matched the Aluminum 380 alloy, so I purchased one pound of 2319 welding wire, which is recommended for welding this alloy.

    I decided to machine off the existing boss because the crack around it would be difficult to grind out and the threads in the boss were stripped as shown below anyway. What was left of the threads were also filled with RTV.

    5. Stripped threads on drain plug boss


    Click image for larger version  Name:	5.  Stripped threads on drain plug boss.jpg Views:	1 Size:	102.6 KB ID:	702898
    sigpic
    Miller Thunderbolt
    Smith Oxyacetylene Torch
    Miller Dynasty 200DX
    Lincoln SP-250 MIG Welder
    Lincoln LE 31 MP
    Clausing/Coldchester 15" Lathe
    16" DuAll Saw
    15" Drill Press
    7" x 9" Swivel Head Horizontal Band Saw
    20 Ton Arbor Press
    Bridgeport

  • #2
    Because drain plug boss was cracked on three sides and only supported on one side, I decided to cut it with a hole saw, because I was concerned that a more aggressive means (Such as a large end mill) might damage the casting if the tool caught and ripped off the boss.

    6. Setup to hole saw off the boss.

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    7. Hole sawing off the boss

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    Click image for larger version

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    Now that most of the material was removed, I could use a boring bar to remove the rest of the material and open the hole up to a standard size.

    8. Boring the hole to size.

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    Next I made a replacement boss for the drain plug. My friend didn't want to add the threads at this time because it is primarily required for the PCV valve that he didn't want to add just yet.

    9. Turning and parting off the new boss

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Name:	9. Turning and parting off the new boss.jpg
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    10. Grinding a drain passage in the top of the drain boss

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    sigpic
    Miller Thunderbolt
    Smith Oxyacetylene Torch
    Miller Dynasty 200DX
    Lincoln SP-250 MIG Welder
    Lincoln LE 31 MP
    Clausing/Coldchester 15" Lathe
    16" DuAll Saw
    15" Drill Press
    7" x 9" Swivel Head Horizontal Band Saw
    20 Ton Arbor Press
    Bridgeport

    Comment


    • #3
      Next I went over the cracks with the TIG torch to bubble the impurities to the surface. It also showed up the crack as a black line.

      11. TIG heating the cracks to bubble up the impurities

      Click image for larger version

Name:	11. TIG heating the cracks to bubble up the impurities.jpg
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      Now that the cracks were visible I ground them out from the inside of the casting.

      12. Grinding out the cracks from the inside of the casting.

      Click image for larger version

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      To keep the casting from cracking we preheated it before welding to 250 degrees F.

      13. Preheating the casting

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      Next I welded up the cracks from the insides. In some cases I had to grind out the weld and re-weld it because there was still too much porosity in the weld. below is a picture showing the welds on the inside of the casting. It was difficult to weld because the casting was hot and the walls got in the way of the torch and filler rod. Below are the welds on the inside of the casting.

      14. Welds on inside of casting

      Click image for larger version

Name:	14. Welds on inside of casting.jpg
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      sigpic
      Miller Thunderbolt
      Smith Oxyacetylene Torch
      Miller Dynasty 200DX
      Lincoln SP-250 MIG Welder
      Lincoln LE 31 MP
      Clausing/Coldchester 15" Lathe
      16" DuAll Saw
      15" Drill Press
      7" x 9" Swivel Head Horizontal Band Saw
      20 Ton Arbor Press
      Bridgeport

      Comment


      • #4
        Then I ground out the cracks from the outside of the casting and welded it up.

        15. Welding the outside of the casting

        Click image for larger version

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        16. Welds on outside of casting

        Click image for larger version

Name:	16. Welds on outside of casting.jpg
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ID:	702913
        sigpic
        Miller Thunderbolt
        Smith Oxyacetylene Torch
        Miller Dynasty 200DX
        Lincoln SP-250 MIG Welder
        Lincoln LE 31 MP
        Clausing/Coldchester 15" Lathe
        16" DuAll Saw
        15" Drill Press
        7" x 9" Swivel Head Horizontal Band Saw
        20 Ton Arbor Press
        Bridgeport

        Comment

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