Hi Meli:
I have a running John Deere tractor that I am going to refurbish. When it is cranking over at start up I hear what seems like a loud knock. I don't hear it while it is running but do hear it again at shut off. What may it be? I plan on rebuilding the engine so I guess it will eventually be taken care of. It would be nice to have an idea as to what it could be so that I can prepare.


Hi Jim,
    It is SUPPOSED to do that!    What you are hearing is the recoil mechanism in the magneto. At VERY low rpms it winds itself up, and then it RECOILS and gives the mag a spin (THAT'S what makes the "click"), so that there will be a HOT spark just at the right moment. Once the engine is running, centrifugal force disables the recoil. It is no longer necessary because at higher rpms the mag will provide a good spark on its own. When you shut down the engine, you will hear the recoil mechanism again because just before the engine speed drops to ZERO, the recoil will become active again as the engine makes its last gasp.
Pay Attention!!!

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