1945 M will not start! HELP!

I have a Farmall M that was running fine until a couple of weeks ago. It is something electrical, as I am not getting any power to the starter. It had a bad battery when I got it, as I had to jump start every time. That quit working, so I went out and bought a new battery. Still nothing. I have a voltmeter, and I get 12.5V @ the battery and at the junction block (not sure what it is called- where the battery cable goes into, and has heavy cable going from it to starter). I am getting 11.4V on each side of my "PUSH OFF/PULL RUN" button when pulled out. Any ideas where to look?

I am getting 4.8V @ the wire on the battery side of the previously mentioned "junction block", but nothing on the other side.

How do I look into my push to start button?

Probably need the new dimmer sw type.

The drop in voltage indicates bad connections, or badly corroded wires. You should have 12.5V all the way.

What "junction block" are you talking about? There shouldn't be any junction block anywhere. One thick wire from one battery post to a bolt on the tractor's frame. The other thick wire from the battery goes to one terminal on the pushbutton switch, then another thick wire goes from the pushbutton switch to the starter.

First thing you need to do is take each connection apart and make sure that everything is clean and shiny, then reconnect them and make sure the bolts are tight. If either of the battery ends is one of those replacement ones that bolt on with a strap, you need to take that apart and clean it up as well. It wouldn't hurt to cut off the end of the wire that was clamped and strip off some fresh wire to make the connection.

As a general rule, you'll find a bad ground connection, the one that goes from the frame of the tractor directly to the battery. The iron/copper connection gets corroded more easily.

If all the connections are clean, bright and tight, and you still have no start, replace the heavy pushbutton starter switch. There's a reason these aren't used to start vehicles anymore, and it's because they don't last...

I will take some pictures of the "junction block"-

There is a 4 terminal block in front of the fuel filter (glass globe). It has one heavy gauge wire coming to it from the + battery terminal, then another going into the starter. It also has two thin gauge (16ga or so) wires coming off of it. The first one (closest to the battery terminal side) goes to the "PUSH STOP/PULL RUN" button. There are about 5-6 wires that branch out off of that button. Two of these wires have in-line fuses and another has a flasher. I checked the fuses and they are good. I believe they power the rear spotlight and the fender mounted yellow flashers. The difficult thing is all the wires are bound together very tightly and I need to get some replacement zip ties before I want to start cutting them all out. That and the wire colors are all red and black, and are not used correctly (red is not all + and black is not all ground - for example one of my in-line fuses has a red wire going into one side and a black wire coming out the other. This wire is hot when the ON button is out and should be +).



I will clean all contacts as I thought I should be getting 12V (or high 11V at least!) at all contacts. I believe my junction block is a relay for the starter. I just can't figure out where the disconnect is, although I have a feeling it is the push button starter. I was just wondering if anyone knows how to go about testing it?

Where do I find a replacement or can I repair this one? Thanks for the help so far!

~Kevin

sounds like someone put a solenoid in the wiring harness when they did the 12v conversion, more than likely a ford solenoid. two big posts on the bottom, two little posts on top. big battery cable comes from battery to big terminal on solenoid, then on other big terminal, that cable goes to the starter. the small terminal on top will have a wire going to the start button. if you want to test the solenoid, get some #12 insulated wire and touch one end to the big battery side cable on the solenoid, then momentarily touch it to one or the other top little terminals. if the solenoid is good, it will engage the starter.

Sounds like a starter solenoid. Does it look similar to this pic. Hal

It does look a lot like that (although mine is a little different, like the same thing only an older model or something). I'll take pics of it- not sure if that is the problem or not though, I do not get any power to the left side front post. I will try and jumper the two and see if the starter kicks in. Thanks much for all the help! I need this tractor to run, it has my loader on it and manure is starting to pile up! ;-)

Be careful when jumping across the small terminals
make sure the tractor is out of gear and the brakes set. One of those small terminals should have an S on it. That only gets voltage while cranking the engine. The other small terminal should have voltage on it all the time and proably feeds voltage to your ignition switch, lights and starterbutton or to a key start
switch. Hal
PS: If your battery cable is connected at the solenoid you need to remove the battery ground and remove the battery cable at the solenoid and clean the cable until shiny and if corrosion is on the solenoid clean it too. Then reconnect the battery cable and reconnect the ground cable last.

KStatz: In my little town the "long necked" push button starters are hard to get--so I rebuild the old ones. It is very simple-- pry up the tabs on the bottom that hold in the base, you will find a wedge-shaped copper contact. Clean it 'til its bright and also the contacts at the posts. I routinely replace the insulation on either side of the wedge-shaped contact--usually with plastic trimmed from a coffee can lid. Reassemble--bend the tabs back in place and check across the posts with a multimeter while depressing the button.

Mr Kirsh I'm not wishing to start an argument here just difference of opinion. I would like to know where i find a switch that will last for fifty years like that and not need to be cleaned once in a while. The ones made today will not be around in half that time.
As for the real problem at hand about not starting I would dump that relay switch and go back to the original setup. We have been going to the group 31 batteries with the 3/8 thread stud on top as they take less cleaning and are cheap as I get them from my semi and not all are bad. I change the set and use the good ones for the farm

Hal, with respect, the "I" terminal on the starter relay is not hot all the time, it is switched separately but at the same time as the connection to the starter motor. If it were it would feed Ignition to bypass the ballast resistor all the time, or back feed into the starter and short out the ignition. It is a separate contact inside only "on" when the starter is engaged. Jim

OK so I spent today (finally got some good weather!) looking at the tractor and I believe my starter selenoid is bad. Even when I jump across the I and S terminals I get no power to the starter lead. I took it off and tested it with a small battery (8.2V RC Car battery) and I get 8.2V @ the I and the input when I connect it. If I jumper across the I and the S I still get 0 Volts to the starter side.

My next question is now where do I find a replacement? This is a Ford Selenoid? Can I bring it to Autozone and get a replacement or do I need to go to a Ford dealership (or a Ford tractor place)?

Thanks in advance!
PS - I also removed all connections and cleaned them with a wire brush, the + and - battery terminals, the tractor ground, the push button to activate the starter (I removed it and tested it and it gets connection when depressed) as well as the back side of my ignition pull switch.

Unless my starter is bad too then with the new seleniod I should be good to go. Any way to test the starter without the selenoid?

Thanks!
~Kevin

So where do I find a replacement selenoid, and how do I test the starter with a bad selenoid without burning it up?

Thanks in advance!
~Kevin

708-768-3869

solenoids can be had at any parts stores. Just take it in. You can test the starter by using a set of jumper cables directly to the battery. Solenoids are fairly inexpensive as well.



T.C.

You can get these solenoids from NAPA or Advance Auto... Just ask for one off of a Ford Truck. If you have a good parts guy and bring in the old one, they should just be able to grab it off the shelf. I had to do the same thing last year to my M.

I tested to see that my solenoid was bad by directly touching one of the battery cables to the starter post, and that turned things over. Not something I would do all the time, but worked for what I needed it to.