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7.5 Hp Fairbanks Morse Rebuild

Discussion in 'Quitters' Club' started by garage gnome, Feb 6, 2023.

  1. Feb 6, 2023
    garage gnome

    garage gnome ECJ5 welder

    Western MA
    Joined:
    Jun 19, 2009
    Messages:
    3,083
    I picked this Fairbanks Mose up back in June. It's nothing too special, but is is a nice complete unit.

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    I started taking it apart today.

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    The hopper has a pretty nasty crack in it. The hopper is full of leaves and junk. It must have froze and cracked.

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    The head is cracked as well.

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    At least the combustion chamber looks good.

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    The rings look to be in good shape as well. Take note of the hole in to piston too.

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    Typically the grease cup (circled on right side) faces up to allow for easy access to grease the connecting rod. The hole in the piston also needs to face up so the oil from the drip oiler can ooze in and lubricate the wrist pin. Someone, either a farmer before me or the factory put it together wrong. The grease cup was facing up and the hole in the piston was facing down when I took it apart.

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    The wrist pin looks like it got pretty warm to discolor the metal like this. Also, the wrist pin retainer bolt was snapped off (on the left of the wrist pin). My guess is, the wrist pin bushing seized onto the wrist pin when it was running and the retaining bolt snapped. The nail was being used as a cotter pin to keep the retaining bolt from backing out. :rolleyes:

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    I made up a new retaining bolt on the lathe. The wrist pin bushing is still in good shape too. It doesn't seem to have much slop in it.

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    Twin2, dozerjim, Ol Fogie and 4 others like this.
  2. Feb 7, 2023
    garage gnome

    garage gnome ECJ5 welder

    Western MA
    Joined:
    Jun 19, 2009
    Messages:
    3,083
    Got the piston and connecting rob back in today. I had to make a special tool to ream out the wrist pin bushing since it was so messed up from being beaten around. I took a 1.375" hole saw and wrapped some masking tape around it. Then I wrapped some 80 grit sand paper around it. The hole needed to be 1.500". Well that worked perfectly!

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    Also made up a new head gasket and repaired the cracked head.

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    This thing sure has some compression! Hopefully tomorrow it will make some noise.

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    jeepstar, 47v6, Fireball and 3 others like this.
  3. Feb 7, 2023
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
    Joined:
    Jul 30, 2003
    Messages:
    8,513
    I enjoy watching you working on these and bringing them back to life.
     
  4. Feb 8, 2023
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
    Joined:
    Jun 15, 2003
    Messages:
    2,132
  5. Feb 8, 2023
    garage gnome

    garage gnome ECJ5 welder

    Western MA
    Joined:
    Jun 19, 2009
    Messages:
    3,083
    I don't like the looks of locknstitch. The screws never rust up. my cast iron filler rod blends in so much nicer.
     
  6. Feb 8, 2023
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
    Joined:
    Jun 15, 2003
    Messages:
    2,132

    Certainly. I'm assuming you are comfortable welding cast then. Way better for sure. I'm assuming you pre and post heat as well?
     
  7. Feb 8, 2023
    Dne007

    Dne007 Well-Known Member 2024 Sponsor 2023 Sponsor

    Cypress, Tx
    Joined:
    Sep 2, 2019
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    1,549
  8. Feb 9, 2023
    garage gnome

    garage gnome ECJ5 welder

    Western MA
    Joined:
    Jun 19, 2009
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    3,083
    I just let it naturally cool. And I do preheat it.
     
  9. Feb 9, 2023
    garage gnome

    garage gnome ECJ5 welder

    Western MA
    Joined:
    Jun 19, 2009
    Messages:
    3,083
    I took the mag apart and well, it's toast. It was full of water and everything was badly corroded. Luckily, there is one on eBay, so hopefully I win it.

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    In the meantime, I took the mag off my 5HP Fairbanks. Good thing the 3, 5, 6, and 7.5HP engine all use the same crank and cam gears. Actually, the 3HP became the 5 and the 6 became the 7.5HP engines. They did this by increasing the RPM and water hopper size.

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    And after a couple flips of the flywheels, it fired up!



    I decided to tackle the crack in the hopper now that it runs.

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    I decided to braze it up. After grinding it down and hitting it with a flap wheel, it gave it a really cool appearance. If you can't hide the repair, might as well embrace it!

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  10. Feb 9, 2023
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
    Joined:
    Feb 9, 2018
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    5,624
    Nice job on the brazing!
     
    dozerjim and garage gnome like this.
  11. Feb 10, 2023
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
    Joined:
    Jun 15, 2003
    Messages:
    2,132
    Yeah, nice brass work, my grandfather would use old coat hanger wire and oxy/acetylene.. No joke... I've gotta rebuild the mag on my JD B.. too many other projects to get there yet.. haha.. I did get my Cub Cadet 1650 moving again. Had to replace the stator, which pretty much requires dismantling half the tractor..
     
  12. Feb 10, 2023
    dozerjim

    dozerjim Member

    western New York
    Joined:
    Nov 22, 2010
    Messages:
    966
    x2
     
  13. Feb 10, 2023
    garage gnome

    garage gnome ECJ5 welder

    Western MA
    Joined:
    Jun 19, 2009
    Messages:
    3,083
    Tackled the seat/toolbox and footboard today. Luckily, there was enough original wood to use as a template for the seat back. I cut it out with a jigsaw.

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    And what was left of the original toolbox.

    And I was missing one side of the steel brackets, so I made those up.

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    And the finished product. Still have to stain it to match the drawbar. This is my favorite part about old engines, you get to work in multiple medias, wood and steel. Both are just as fun.

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    I made the drawbar yesterday and put it on today. The eyelet at the end was made a by a blacksmith. It was pretty cool to find that.

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    jeepstar and Twin2 like this.
  14. Feb 12, 2023
    garage gnome

    garage gnome ECJ5 welder

    Western MA
    Joined:
    Jun 19, 2009
    Messages:
    3,083
    I made up a new throttle linkage. The original one held the throttle plate open at a quarter throttle. By doing so, the engine would bounce like crazy on the cart. My new one is adjustable, so now the throttle plate stays closed now and it runs nice and slow. :cool: Also replaced the spring on the throttle shaft.

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    And of course everything is all stained now.

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    I love the way it runs now. Just need a new gas tank and it will be show ready!

     
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