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Welding on small engines

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  • Welding on small engines

    Yes, I have already tried a search on this topic with no luck. The question is this: have any of you experienced any problem with the engine starting after welding on things like handles on lawn mowers that have small engines, like a 4-cycle one-cylinder engine? I'm talking about the recoil-start non-battery type. (I already know about all the pro's and con's of welding on vehicles.)

  • #2
    I have done many without any problems at all. I weld on my buddy's mower deck all of the time and he has never complained, as a matter of fact we put a new skirt around the bottom of his kubota last week.

    Wheelchair

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    • #3
      I have a friend that has a mowing business. I've repaired (welded on) several of his big riding mowers with no issues.
      Jim

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      • #4
        Some of the ignition systems contain a primary coil which contains solid state components, those could possibly be destroyed by the arcing in close proximity.

        I welded on a motor mount on a Zenoah engine which has one of these solid state primary coils on it, with high frequency and it didnt destroy it, maybe I was lucky..............
        mike sr

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        • #5
          The 3 things that are most likely to cause unseen harm are:

          *Resistive heating through a current path

          *Transient voltages that are either induced electromagnetically or conducted directly

          *Magnetic fields

          If you clamp ground on a crankshaft and weld on an engine block, the current will travel through the bearings, the cylinder walls, the piston, the rings, etc, and these aren't the best conductors since they are coated in oil. There will be microscopic arcing all over and the engine can be seriously damaged or destroyed with enough current.

          TIG with HF can cause enough RFI to destroy poorly designed digital devices. Starting an arc with any process can create transient (ie milliseconds-microseconds) voltages of several hundred volts even on conductors not in the welding circuit. This can blow solid state devices in electrical systems of automobiles. But of course power equipment is a little bit lower tech, and low tech is good if you want to avoid damage. I don't think you'll find anything on that power equipment that will be damaged by anything short of a lightning bolt.

          Magnetic fields can magnetize, demagnetize, or reverse the magnetic polarity of metals. You can ruin some DC ammeters this way, but I don't think you'll find anything else that would be sensitive to a high magnetic field.

          So really, as long as you ground good and close to where you are welding, and ensure that it doesn't travel through bearings, you're good.

          But if, say, the ignition coil dies, welding will surely be blamed. I welded custom columns in a 3 story residential application and a 25 year old water valve in the owner's home wouldn't shut off. I had to fix that because they thought the welder somehow "got electricity into their pipes."

          Cost of doing business. There is actually a category for that... called "contingency" and 10% works for me. Note it is not called "unforeseen." MLB announcing tomorrow that the steroid cheats are out and Pete Rose is in would be an "unforeseen event." Paying for something you didn't break because you are in business is not just foreseeable, but a fact of life you better bank on.

          80% of failures are from 20% of causes
          Never compromise your principles today in the name of furthering them in the future.
          "All I ever wanted was an honest week's pay for an honest day's work." -Sgt. Bilko
          "We are generally better persuaded by reasons we discover ourselves than by those given to us by others." -Pascal
          "Since we cannot know all that there is to be known about anything, we ought to know a little about everything." -Pascal

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          • #6
            Originally posted by Bodybagger View Post
            I welded custom columns in a 3 story residential application and a 25 year old water valve in the owner's home wouldn't shut off. I had to fix that because they thought the welder somehow "got electricity into their pipes."
            that's some pretty funny chit right there....
            miller dynasty 350
            miller spectrum 1000

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            • #7
              Originally posted by reggie
              Arcing of bearings????
              NEVER place your ground where current will travel through a bearing when you weld. There is a chance that it will arc between the bearing races and rollers causing rough spots that will lead to bearing failure.
              Jim

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              • #8
                Thanks, guys. You have re-inforced what I suspected.

                Thanks especially to Bodybagger and Popspipes. That is some serious info you have relayed there.

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                • #9
                  "Arc-Racing"

                  Originally posted by Jim-TX View Post
                  NEVER place your ground where current will travel through a bearing when you weld. There is a chance that it will arc between the bearing races and rollers causing rough spots that will lead to bearing failure.
                  So, it's not a good idea to hardface the blade,while it's running?

                  Dave
                  "Bonne journe'e mes amis"

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                  • #10
                    ive welded many vehicles/ equipment, put ground close to work, remove ground on battery, that all i ever did, never any problems, i seen a guy ground to the neg cable on the bat which was still connected and then tried to weld on the back bumper on a service truck, both head lights blew out, after that he was fired, his first screw up was welding parts on top of empty 55 gal laquer thinner barrel, with expected results

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                    • #11
                      Originally posted by davedarragh View Post
                      So, it's not a good idea to hardface the blade,while it's running?

                      Dave
                      Sure, it is. It cools much quicker that way!

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