John Deere Magneto Repair


| July/August 1984



If you are tired of paying more to have someone fix your engine's magneto than the entire engine itself cost, then you should consider repairing the magneto yourself. Many of the John Deere Type E engines in original condition have magnetos that fail to produce a spark. In some cases if they do have a spark, it is too weak to allow the engine to run. Usually, a good thorough cleaning of all the parts will be enough to bring back a good spark to the magneto. If most of the major parts are not cracked or damaged, anybody with a few tools can disassemble the magneto, clean it, reassemble it, and 90 percent of the time it will work. After the magneto has been removed from the engine, the first thing to do is gather all of the necessary materials.

There are only a few things needed: a screwdriver, pliers, an adjustable or open end wrench, and a scraper along with WD-40, clear, black, and aluminum spray paint, and some light oil. Two of the most important things are rags and a parts can.

After these materials are gathered, you can begin work. First wipe off as much of the dirt in the magneto as possible and spray all screws and nuts with WD-40. Next, remove the wire from the magneto by loosening the screw where it is attached. Then try unscrewing the large, round black plug the wire was connected to. If it does not come off by hand, carefully use pliers to unscrew it. After you pull this out, slightly stretch the spring and clean the black pick-up at the bottom.

Now unscrew the two screws on each side of the center strap that holds the horseshoe magnet in place and remove the strap. Firmly hold the base and try to pull off the magnet. If it does not come, lightly tap it with a rubber hammer (do not use metal because if you hit it too hard, you could reduce the power of the magnet). Then mark which direction it came off. Next, grab the gear firmly with your hand, use a wrench to remove the nut from the shaft, then pull off the gear. Be careful not to misplace any of the pieces. Now you have all of the external parts removed. The next step is to take apart the inside.

First, remove the four screws that hold the cap on. Slowly pry the cap off with a screwdriver, being careful not to damage the gasket. After the cap is off, slowly pull out the armature. (Make sure you have removed the black plug that the wire hooks up to as explained above because if you do not, you will break the armature.) Once the armature is out, use a rag to wipe it off, inspect it for damage and set it aside. Now everything is apart and each piece is ready to be cleaned.

Generally, everything except the armature and the black plug that takes the spark from the armature can be cleaned. Scrub everything else with soap and hot water until all dirt is gone. Next, wipe the individual parts dry with a rag and set them on some newspaper to air dry. After all the parts are dry, you can paint them if you want the magneto to look like new. Either clear or aluminum paint can be used on the base,- and black paint on the magnet. Spray paint usually works best because it goes on smoother and dries quicker. After the paint has had enough time to dry, you can begin reassembling the magneto.