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Farmall & IHC Tractors Discussion Forum
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Farmall B switch

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Dave H (MI)

07-25-2007 16:11:07




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Getting around to working on the Farmall B that stopped running a while back. I am thinking an electrical problem and started at the battery. I am no mechanic but it seemed logical to start there so I gave it a good charge. In trying to see if it would turn over last night I was looking at some of the connections and noticed one of the two posts on the bottom of the upright pull-type switch was busted off. Pretty sure this could be a problem but not exactly positive.
I looked at the battery and the switch and the starter and it looks to me like the battery goes direct to the starter and that as long as the battery is hooked good to the starter and has a good ground the starter should work. Am I right or will the starter not crank with a bad switch?
I guess my question is....what exactly is the purpose of the switch? Thanks guys!

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Idaho Ron

07-25-2007 20:44:36




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 16:11:07  
I had much the same problems with my SC. I got a drawing of the wiring diagram. I tested every connection with a OHM meter. I was not getting full strength. I took off every connection and wire brushed them. Finally I could turn on the ign, switch and I could get a reading from the alternator connection to the coil. I tried the starter with a good 12v battery and it would just hardly turn over. I took the starter off and took it apart. I used electronic cleaner and a wire brush to clean it like new. I put new grease on the threads that the gear ride on and put it together. It fired the tractor right up. I cleaned the starter on the Model A and sure enough IT will start with the starter too. That starter has not worked in 20 years. Ron

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Owen Aaland

07-25-2007 21:26:08




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 Re: Farmall B switch in reply to Idaho Ron, 07-25-2007 20:44:36  
It is not a good idea to use grease on the starter drive assembly spiral. It can cause the drive to drag enough so that it does not engage the ring gear teeth before starting to turn. You may get by with it in warm weather, but when the grease gets cold and stiff the drive will not get engaged before the starter gets up to speed. (BTDT) That is the reason the repair manuals say to lube with light oil.

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Dave H (MI)

07-25-2007 18:25:40




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 16:11:07  
Thanks guys! Scotty has the description on this switch down to a "T". It is exactly how he described it and, yes, it does have a wire that runs to the coil as well as one that runs to the box with the ampere meter on it. I have to get a new switch as this old one is really shot. Can I take the wires from the two switch posts and hook them together until I get the switch? I guess the first order of business based on what everyone tells me is that the starter should crank and it doesn't. Since it did before now I am thinking the battery charge and cleaning the terminals may be the fix to that. Then I will need the switch to diagnose what all else might be ailing her (?). Can't post a pic or even get out to look at her because I am stuck at work tonight. I'll try to get some time after dinner tomorrow....have to work in the AM too (and glad of it!)

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El Toro

07-26-2007 08:22:48




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 18:25:40  
If the old battery cables are frayed or cracked I would replace them with 00 cables and use soldered
lugs on the cable ends, then clean them too. Hal



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Janicholson

07-25-2007 18:35:47




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 18:25:40  
Sure that will give it juice to the coil. Even a plain old house wall switch with some tape wrapped on it would allow it to be stopped easily. Clean those terminals so the starter turns. If the starter still won't make it turn, I would put it in high gear and rock it back and forth violently with the rear tires. This can jar loose a stuck starter. If this does not successful, take off the starter (while loosening the bolts, if you hear solid click, re-tighten them and try it. If nothing still, the starter may need to be checked at a Electrical systems repair store. JimN

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billde

07-25-2007 18:31:12




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 18:25:40  
Yes you can twist the 2 wires together, simply pull them apart to shut her down. Cap the wires after you shut it down so you don't have a ground out.



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billde

07-25-2007 17:43:44




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 16:11:07  
Also, if the push-pull switch has 2 terminals it must be set up with a distributor as a mag kill switch has only 1 terminal. So, you need both wires hooked up to the switch to energize the coil.



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ScottyHOMEy

07-25-2007 17:40:04




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 16:11:07  
Dave, if the button switch has two contacts on the bottom, it is for a battery ignition.

On mag ignitions, the switch has a single pole and is used to ground out the mag and kill the engine when it is pushed down.

On a battery ignition, the closed (meaning pulled up) switch provides continuity of juice to the points and therefore the coil. With the two-pole swithch in the "up" position, juice will flow through the points to the condenser and coil to make her work like she ought to. Pushing the button down breaks that continuity and shuts her down.

In neither case, battery or mag ignition, does that switch have anything to do with whether or not the starter will turn the engine.

I'm pretty sure a new switch will fix what 's ailin' her, but if you want to test it, look around for a dangling wire that may just have a terminal and a screw attached to it. Use what you have, but a test wire with aggilator clips on both ends that you can use to re-establish the connection would be ideal. Hook that loose wire back up to the busted-off post as best you can, and see if she runs.

I'm thnkin' real strong that a new swith and maybe some wirin' is called for.

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billde

07-25-2007 17:14:26




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 16:11:07  
The little push-pull button has nothing to do with the starter turning. There is a spring loaded plunger on the starter that is activated by the starter rod, take a screwdriver or punch and push down on that plunger. If the contacts are good inside it will turn over.
Let us know what happens.



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Janicholson

07-25-2007 16:47:50




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 16:11:07  
There is a switch on the starter. It is the device the big cable is attached to. There should be a mechanical (pull rod) attached to this switch. If these (and a good battery ground are connected, the engine should spin over (it may not start, but it will turn over.
The other switch is either a mag kill switch that is open when pulled out , and closed (conducting) when pushed in.
If it has a coil and distributor, not mag, the ignition switch is open when pushed in, and closed when pulled out. This switch shuts off electricity from getting to the coil, thus stopping the engine when pushed in.

A wire off of a coil system will keep it from running, but not cranking. A wire off of a Mag system will let it run but be unable to shut it off. Tell us more details. JimN

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El Toro

07-25-2007 16:47:44




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 Re: Farmall B switch in reply to Dave H (MI), 07-25-2007 16:11:07  
It would help if you posted a picture of the switch. You need to determine if the tractor has a magneto or a distributor on the engine. If it's a distributor you are going to need battery voltage fed to the coil and distributor. That is usually fed from a switch near the tractor driver to the coil and to the distributor. The mag has a grounding wire that will ground out the mag to stop the engine. It doesn't require any battery voltage at all. If there's a small cylinder shaped device with some wires attached to it could be a coil. The big wire out this will go to the distributor. You need to clean all those battery posts and cables until nice and shiny. That includes the where the is grounded on the tractor and at the starter. It should then crank
but, may not start. If its 6 volts they usually use the + battery terminal as ground. Hal

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