[Farmall] More M electrical problems

[Jim Becker]

Dean,
You have a bad starter switch.  It has an internal short that is putting 
voltage to the starter switch housing when you hit the button.  The switch 
housing is grounded to the tractor through the mounting screws.  In this 
case, it appears that one screw is not making a connection and the other 
(the hot one) is making a connection that has enough resistance to cause it 
to heat up.

Why the starter didn't turn when connected directly to the battery is 
another question.  You did have the starter frame grounded back to the other 
battery post didn't you?

Jim Becker        jim.becker at verizon.net

----- Original Message ----- 
From: "Dean Vinson" <dean at vinsonfarm.net>
To: "'Farmall/IHC mailing list'" <farmall at lists.antique-tractor.com>
Sent: Monday, October 30, 2006 6:49 AM
Subject: [Farmall] More M electrical problems


> The starter motor on my 50 M seems to have quit, and there's something 
> going
> on around the starter switch that I don't understand.
>
> Wouldn't start yesterday afternoon.  The starter gave a little click, and 
> I
> noticed a brief little puff of smoke from down near the starter switch, 
> but
> nothing after that.  I made sure the battery was charged up and tried 
> again,
> and there's definitely some current flowing around that switch somehow.
> It's mounted to a piece of metal down below the gas tank, and one of the
> little machine screws that holds it on there would glow red-hot if I held
> the switch down for a few seconds.  After that one initial click, nothing
> more from the starter.
>
> It was getting dark so I took the battery out and the starter off and
> brought them both inside.  Hooked the starter up directly to the battery,
> and still nothing happened--no movement, but also no short, no current 
> draw.
> So I'll stop by a local electric shop and have the fellow there take a 
> look.
>
> But meanwhile, what would cause that little screw by the starter switch to
> get red hot?   It only gets hot when I close the switch, so the switch
> itself seems to be functioning okay.   But with the switch closed, the 
> whole
> frame of the tractor should be part of the circuit:  battery to switch to
> starter motor, then back to the battery through ground.  The screw is
> obviously grounded--so why does it get hotter than some other random screw
> elsewhere on the tractor?
>
> Not to mention why is there even any current flow to begin with, if the
> starter motor isn't pulling it?
>
> Dean Vinson
> Dayton, Ohio
> www.vinsonfarm.net