March 20, 2009

• John Deere "B" won't start

  My dad and I both have John Deere Model "B" tractors.  Mine is more or less the way it came out of the factory in 1949, sans a few repairs to keep it running.  We don't know as much about dad's because it came from an auction instead of being inherited from a family member.  His "B" has been modded to a 12-volt electrical system.  Also, his "B" won't start.  Granted, it did the day before he bought it, just not the day of.  Or ever since.

  We've taken the starter out to get it checked, and the tests came back that it was fine.  Today I took my multi-meter to both tractors.  I disconnected the negative terminal of each battery and measured the resistance across the battery cables while pressing the starter button down.  My "B" (the one that runs) has a resistance of about 0.2 Ω.  My dad's tractor has a resistance of about 25 kΩ.  So (assuming these stay the same when actually trying to start) I can pull about 30 A when starting and dad can pull about 0.00048 amps when starting.

  My next step is to find some long bits of wire to see if I can find out where the bulk of that 25 kΩ resistance is.  My guess is that the starter is actually bad, or perhaps one of the wires running to the battery is disconnected partly or corroded.  If anyone has any ideas or experience with a problem like this, please let me know your thoughts.

  • 2:01 pm
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