[AT] Farmall starter switch

[k7jdj at aol.com]

Sounds like the starter is stuck.  Don't know what kind of starter drive is used.  I would try and make sure the engine is free and or put tractor in a high gear and rock rear wheel with the ignition switch off.  Also put a voltmeter on the battery and see what the voltage does when you apply start current to the battery either with the switch or putting the battery cable on the starter.  It should drop a couple of volts if the starter and grounds are OK.

Gary
Renton, WA.


 

 

 

-----Original Message-----
From: Dean Vinson <dean at vinsonfarm.net>
To: 'Antique tractor email discussion group' <at at lists.antique-tractor.com>
Sent: Thu, Jul 24, 2014 3:39 am
Subject: Re: [AT] Farmall starter switch


Claude, thanks--now that I think about it, I remember that from working on the 
other M years ago.  Makes sense.

Dean


-----Original Message-----
From: at-bounces at lists.antique-tractor.com [mailto:at-bounces at lists.antique-tractor.com] 
On Behalf Of Claude
Sent: Thursday, July 24, 2014 6:11 AM
To: Antique tractor email discussion group
Subject: Re: [AT] Farmall starter switch

Starter current does not go thru ammeter. Too much current.

Claude

Sent from my iPad

> On Jul 23, 2014, at 9:56 PM, "Dean Vinson" <dean at vinsonfarm.net> wrote:
> 
> Nuts.   Got to thinking, "That might just be a bit too easy," so I went back
> out, reconnected the starter cable to the battery, and touched the other end
> of the cable to the bare post on top of the starter motor.   Big sparks but
> no response from the starter motor--so my theory that the switch 
> simply wasn't making contact appears to be incorrect.  Time to take 
> the starter motor off, but that's a task for another evening.
> 
> Before doing anything tonight I'd once again tried to start the tractor
> normally, and watched the ammeter while doing so.   Nothing.   Ammeter
> deflected just fine when I turned the lights on, so I'd assumed the 
> lack of any noticeable deflection when I pulled the starter switch meant there 
was
> no current flowing and the problem was in the switch itself.   But bypassing
> the switch sure didn't get that starter motor moving.   Did make a new
> little arc divot in the top of the post on the starter, though.
> 
> Dean Vinson
> Saint Paris, Ohio
> 
> 
> -----Original Message-----
> From: Dean Vinson [mailto:dean at vinsonfarm.net]
> Sent: Wednesday, July 23, 2014 9:22 PM
> To: 'Antique tractor email discussion group'
> Subject: Farmall starter switch
> 
> The Super M wouldn’t start the other day, wouldn’t even show any sign of
> trying to turn over, despite plenty of battery power.   Tonight I had time
> to take the starter switch off the starter motor (this is a late Super 
> M, with the switch mounted right on top of the starter motor, rather than
> behind the fuel tank support like on an M or early SM).   The spring-loaded
> copper contact plate inside the switch and the copper post on top of 
> the starter motor are both all chewed up where they come into contact when the
> switch is pressed.   I assume an electric arc occurs when I make or break
> that connection, probably boosted quite a bit by the tractor’s 12-volt 
> conversion, and over time those arcs have removed enough material that 
> the contact plate simply doesn’t reach the copper post any more so the starter
> motor never receives the “go” signal.    Anybody ever run into something
> like that?  
> 
> http://www.vinsonfarm.net/photos/SM_starter_switch_post.jpg
> http://www.vinsonfarm.net/photos/SM_starter_switch_housing.jpg
> 
> Coincidentally enough, some years ago the starter switch on the 1950 M 
> I had at the time quit working--but it was the opposite problem, too 
> much electrical contact rather than not enough.  I fixed that one by 
> replacing the worn-out cardstock insulation with some polystyrene 
> modeling sheet, to keep the moveable switch plate from directly 
> shorting out to the switch
> housing:
> 
> http://www.vinsonfarm.net/photos/M_starter_switch_1.jpg
> http://www.vinsonfarm.net/photos/M_starter_switch_2.jpg
> 
> This time I think I’ll look for a replacement switch and hope the post 
> on the starter motor is okay for a while longer... seems like that’d 
> be the easiest fix.
> 
> Dean Vinson
> Saint Paris, Ohio
> 
> 
> 
> 
> 
> 
> 
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