Ford 8N TractorDear Ole Mechanic; 

I am having some problems with my old 8N Ford tractor.  I am trying to update it by installing a 12 volt electrical system in place of the original 6 volt system.  Also, as the starter is the original one as far as I know. I thought it would be best to put in a new one.  That way it could better handle the 12 volts.  The installation of the one wire alternator, coil, points and battery went OK.  I had saved your column on the Ford tractor coil problem and it really helped. 

Now for the problems.  After I put in the new starter, I started the tractor, and it made a horrible noise.  I got it shut off real quick.  Thinking that I had somehow installed the starter wrong, I pulled it back out, checked it over and reinstalled it.  No change in the noise.  I pulled the starter again and checked it next to the old starter, and the shaft with the starter-drive on it was about a quarter of an inch shorter than the original.  I did some measuring, and it was shorter enough that the starter drive would not disengage from the flywheel.  I had the housing machined so that the shaft stuck out further and would letthe starter drive disengage.  I reinstalled the starter, fired it up a couple of times and it worked fine.  The third time I fired it up, the noise was back and louder.  I shut it off and then tried to fire it again.  The starter buzzed but didn’t crank the engine over!.  Out came the starter and part of the starter drive.  After I fished the broken parts out of the bell housing, I reinstalled the old original starter; it worked just fine and fired the tractor right up.  Then, after the tractor sat for about a week before I could get back to work on it, the battery was dead!  It charged up OK and started the engine just fine.  Another week later, the same thing--the battery was dead. but it charged up OK.  What is going on?  Is the starter draining the battery while it sits?  Did I get a bad new battery?  I am about ready to change it back to 6 volts!  Help!

Fed Up


Dear Fed Up;

You are fighting two separate and unrelated problems.  I am going to get the dead battery out of the way first, as you have--in fact--fixed the starter problem.  It is not a problem with the battery--it's an alternator problem.  Well, actually not a problem but a fact of life with one wire hook up alternators.  To make an alternator a one-wire hook-up, a small, solid state-module is used.  Like many small computer chips, there is a small amount of current draw all of the time.  This is not a problem if the tractor is used daily or at least every few days, as the small amount of draw does not drain the battery down far enough that it won’t start the tractor.  The one-wire units that I have checked pull anywhere from 200 milliamps to 500 milliamps all of the time.  To put it another way, 500 milliamps is one-half of an amp.  Over a week with out running the tractor to recharge the battery, it is enough to drain the battery to the point that it won’t start the tractor.  That is why I prefer using the three-wire alternators, but NO, you do'nt need to get another alternator.  All you need is a battery disconnect switch.  They can be had for less than $10.  When the tractor is not going to be used for awhile, just open the switch.  Yes, you could just pull off the battery ground cable, but the switch makes a neater looking installation.  Problem solved.

Now for your starter problem.  It sounds like you got a miss-machined one.  Unfortunately many places have a “No returns on electrical items” policy.  It is probably an “out sourced” starter that comes from a company that is clear out of the country.  You should let the business where you got the starter know that you received a less than usable unit.  Hopefully, if they get enough complaints, they will tighten up on their quality control or maybe even find a USA manufacture to get their starters from.  I do not expect that you will get any satisfaction from them, especially since you had some machining done on the starter, and the drive is now in broken pieces.  There should be no problem if you use the old 6 volt starter unless the brushes or bushings are worn or there is an internal electrical short.  At 6 volts the starter uses more amperage to do the work, so heavier wiring is used.  Putting 12 volts to it means that more of the work is done by the higher voltage, and the 12 volts actually would not need as heavy a wire, so the old starter will work just fine.  I know of one N-Series tractor that has had 12 volts going through the old original starter for more than 10 years now, and it works fine.  By the way, I did check and the same starter part number is used on all 9N, 2N and 8N Ford tractors.  If you are set on replacing the starter, I suggest that you take the old starter with you and compare the old one side-by-side with the new one; if it doesn’t match exactly, don’t buy it.  That's one way to solve the “no returns on electrical items” policy.

Herr Professor Nuzanbolts