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Outboard engine repair - lower unit

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  • Outboard engine repair - lower unit

    This looks like a fun repair, huh?

    It is my buddy's lower unit on a boat he just picked up. The engine has just been rebuilt and purrs like a kitten, but there is some damage to the lower unit that I have been elected by unanimous vote to try and repair.

    Unfortunately, I forgot to take a picture before I started to clean up someone else's FIRST attempt at welding this some time ago (which didn't hold at all). I think the culprit might be the guy below because it looked a whole lot like pigeon $hit!! haha

    Having said that, I might not do much better! I am working with a Millermatic 211 and a Spoolmate. Wish me luck!

    (No doubt, I have a feeling my work will be ground flat and painted.)

  • #2
    I picked up where someone else left off on one of these. They hadn't properly cleaned the material at the joint and was also missing a small piece. I should have cut it off and fit a new solid piece in and shaped as needed after welded. Would have been much easier and quicker in the long run.


    • #3
      I've done a few of those.


      • #4
        Originally posted by Showdog75 View Post
        That's nice lookin' work!

        Here is my start before I have to shut it down for the night... go the wifey taking me out somewhere to eat for my birthday.

        It's not as pretty as you tig boys, but I think I can piece this back together. The biggest problem will be were the anode goes in place. That is a HUGE hole. There is an aftermarket cavitation (sp?) plate that bolts on, hence the holes. I wonder if I even need to fill in this hole. ?? I probably better. Maybe I'll cut a little jigsaw piece and weld it in place.

        Here is a shot of the first pass. Again, no nearly as pretty as a TIG weld!


        • #5
          I do some of those every summer. For the big holes i just lay it on a piece of clean steel and weld over it, instant patch...Bob


          • #6
            what the boat guys appear to do here is put a copper backing strip behind the repair (big hole) and with a spoolgun and preheat, weld to both sides of the crack till its gone then machine the unit to spec.


            • #7
              I've done many of these

              replacement Skegs can be bought. They are of the same grade aluminum as the lower units. Simply cut to match your repair area.

              Here's a link from one supplier:



              • #8
                Originally posted by PA Weldor View Post
                replacement Skegs can be bought. They are of the same grade aluminum as the lower units. Simply cut to match your repair area.

                Here's a link from one supplier:

                that's. Great!


                • #9
                  Your weld is a little grainy which means your material is not very clean, I noticed that You still had a little paint on your preped pc.

                  A grainy weld has contamination in it which makes it weak.

                  Do a little better clean up prior to using filler metal and your weld will be shiny and good.

                  I dont mean to bash you, Just constructive criticism.


                  • #10
                    Outboard engine repair - lower unit

                    Your welding cast aluminum with mig? What are you using for wire?

                    That needs to be tig welded.


                    • #11
                      Thread from January guys, revived by a spammer.


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