Trying To Solve An Electrical Problem On A TO20

I have been offered a TO20 at what would be a very reasonable price, BUT....it has an electrical problem. The tractor was converted to 12 volts at some time in the past and I suspect something was not connected properly. That said, all I know from the owner is "electrical issue where battery gets hot in 15 seconds reduces starter crank and drains battery".

I suspect that somewhere along the wiring harness, someone wired for a negative instead of a positive ground, or that the starter or solenoid is bad. However, am hesitant to buy anything that "needs work"--I'll bet some of you have had experiences that led you to feel the same!

Does anyone have any idea where the problem might lie and how it might be diagnosed? I have a voltmeter and a spare battery for testing purposes. Any advice at all will be most welcome!

Hi Dave M56. I have a TO20 like you. Great tractor. First question, what is a reasonable price? If it runs, and basically everything
else is OK other than your "electrical" then that is a good start. Now, to your electrical. You don't say whether the battery gets hot
while cranking the starter, or if it gets hot when you hook up the battery leads. I'm assuming it's when you start cranking. Does it
still have the original 6 volt starter on it? If so, it's possible that someone before you cranked too long on it, and burned up something
internally. Your description of the battery getting hot (while cranking??) and the starter slowing down is indicative of a major short or
electrical problem in the starter. The battery getting hot is an indication of a huge load on it, more than it was designed for. As
mentioned, if electrical is the only problem, and the rest of the tractor is in good shape (and runs) then I wouldn't shy away from a good
deal. Electricl is pretty much all external stuff and can be readily fixed. Mine is still the good old 6 volt positive ground system. It
starts right up and runs good, but you've got to have really good grounds on everything or it won't work, mainly the lighting. I just
thought of something else.......if you still have the internal starter switch (the one activated by the shift lever) then it's possible
there might be a problem with the switch grounding out as well. I'd start by disconnecting the starter, activating the shifter (switch)
and see if the problem still occurs. If so, you've narrowed the problem down considerably. But again, if the rest of the tractor is in
good shape, electrical wouldn't scare me away. Just my 4.5 cents worth.

Dave, I just re-read the post and noticed that you said "after cranking for 15 seconds" in the statement. 15 seconds is a LONG time to be
cranking. If it hasn't started in about 5 seconds, then it needs a tuneup, or something else. Especially if it has been converted to 12
volts and the starter is still the original 6 volt starter. Putting 12 volts to a 6 volt starter for more than about 5 seconds IS asking for
trouble. If this has been done frequently, then the starter may be "cooked" already.

Not a lot to go on there, but the electrical system on those tractors is as basic as it gets, nothing that can't be solved.

If that's all that is wrong with it, and you were able to get it running and put it through all the gears, and it had oil pressure, held coolant, no broken castings or missing major parts, descent tires, then that's a good start.

Unless you get lucky enough to find someones restored baby that just hit the market, finding a 70 year old tractor that doesn't need work is not likely to happen!

"Reasonable price". I have purchased one of those once. I picked it up for $800 needing an alternator and some slight rewire with near new
tires, good sheet metal and good paint.
From the sound of it, the starter is toast. You can run 12V on a 6V starter. Just don't crank on it for a long period.
If i does not start in about 6 seconds, let it cool for a minute before trying again.
Hope the reasonable price includes the cost of a starter at least.
That and what ever else might be causing it to not start.
If you don't like working on tractors, I heard tell there are new one's for sale just down the street.
I have a TO-20 that after reworking, it pretty much sits there for most of the year on a float charger.
No monthly payments.
Your mileage may vary.