Tractor Repair: voltage leak, cable clamp, field terminal

Question
I am helping a friend with a International / McCormick 434 loader tractor . Originally a British Positive ground I think .. Her problem is that it has never held a charge and has rewind 2 new batteries .
  I have had the alternator rebuilt and also put a new battery in it today.  One thing I noticed Is that I get a 12 volt reading between the ground post and the post clamp with the key off.I also disconnected things until I got a zero reading and found that the alternator bat. wire connection at the starter is the leak.
 When I disconnect the bat. wire the reading goes to zero between the negative post and the ground cable clamp.
      Can you offer any advice on this problem .
          thank you in advance
              Regards , Tim ..

Answer
Hello,

  You are correct, it was built in England and originally had a positive ground generator system.  If the alternator was rebuilt, then obviously something else is not correct ever since it was converted to a negative ground alternator system.  If the electrical draw was gone when you disconnected the alternator wire at the starter, then the alternator is still the problem, so it sounds like the alternator is probably not wired correctly.  Without knowing what type of alternator is on it, I can't offer specific advice on how it should be wired.  If it has an internal voltage regulator, that makes it easier.  The field terminal should only have power to it when the ignition switch is on