1950 Farmall M Problems


New User
Good Afternoon all! I apologize ahead of time for the lengthy post, but I want to try to get it all out there for others to better understand.

Backstory: I have a 1950 Farmall M that was given to me by my grandfather who used to farm with it. He actually even used to pull with it back in the day at a couple of fairs and I have his old photos and trophys. This tractor means the world to me. It sat for probably 15-20 years and last year I finally got it home and got it running again. My goal is to take it to the local tractor pulls this year in July. I have no intention of winning, but its in his memory that I want to do this.

Anyway, this tractor ran pretty well given how long it sat. I did the following engine related work to it last summer:

1. New cap and rotor
2. New points and condensor
3. Completely cleaned full tank
4. New plugs and wires
5. Oil change and new filter
6. Cleaned carb
7. New (shorter) governor spring [however as of today, I changed it back to the original spring]

The tractor ran well since then, but I believe the rings in cylinder number 4 are starting to go as I get a bit of white smoke when shes running. I also noticed that the spark plug for cylinder number 4 had some sort of an extension piece on it which I was told was to eliminate fouling of the plug. I had never seen that before, but a friend of mine apparently has. So I decided this spring to get her back in the garage for an in-frame rebuild.

I got the tractor in, ordered the piston kit, but was told they were on backorder until July a week later. With the pulls in July, I decided I was going to have to forgo the rebuild until this winter. So while she was in the garage I decided to do the following work:

1. Carb rebuild kit
2. New exhaust manifold
3. Cleaned slight sludge as best as possible from top of head
4. Oil change (already had it drained expecting a rebuild)
5. Took the generator apart since it didnt charge and noticed the armature was shorting itself on the field due to a bad brass bushing. Couldnt find the exact bushing I needed and decided to do a 12V conversion.
6. Installed Steiner 12V conversion kit [one-wire alternator, internally resisted coil, new one-wire harness from Brillman]

As of this morning I got the tractor outside and fired her up for the first time. She started immediately and rain pretty well. Still had the little puffs of smoke, but nothing terrible or out of the ordinary. However this leads me to my two issues that I need help with:

1. Installed the Steiner 12V conversion as well as new ammeter and wired it exactly as it was shown and the tractor will not charge. If I unhook wire from alternator, it is producing about 15V, but when I hook it back up it is no longer charging and the battery reads ~12.6-8 volts. The ammeter does not really show a discharge or a charge in either direction. Is there anything else I can do to try and figure this out? Are there any diagrams for one-wire alernators that are different than the one Steiner provides? Do I need a diode even though it is not a 3 wire alternator?

2. Another issue that is new is that when I shut it off with the ignition switch the tractor almost dies but then putts like an old hit and miss motor for another 30 seconds so. Eventually it had a final puff where the motor appears to run backwards for a second and I get a bunch of smoke out of the air filter intake. I have tried a bunch of things here to try and fix this like:

a) installed original governor spring
b) lower idle as low as possible
c) messed around with carb settings, even had the fuel screw completely screwed in and it didnt seem to change anything
d) unwired alternator and it still did the same things [this eliminate a backcharge from the alternator]
e) tightened all wiring connections
f) tried multiple different wiring methods involving the ammeter

Honestly I am at a complete loss. The tractor now smokes pretty good with it running, which seems to be caused from the 'dieseling' that it is doing when I try to shut her down. I read multiple posts about some people just living with it, but I just cant. I'm a guy that stuff like that drives me nuts!

The rebuild kit is now back in stock even thought I talked myself out of it for this year...but because of all of this part of me wants to just do it in case carbon in the cylinders could be causing this...could also just be because Im stumped and angry...

I appreciate yall taking a second to read this post and possibly help me out with it. If you have any questions, or need some more information, please let me know.
not sure about number 1. number 2 when you say lowered idle down are you refering to throttle down? I would throttle all the way down and let run a minute or two and shut off. sounds like its trying to fnish burning all fuel . just my two cents worth. I'm no mechanic but why bother the wiring on number 2 question. doesn
t make sence to me.
Thanks for the reply! When I say getting the idle down I mean
lowering idle on carb. The throttle is always cranked all the way
down during shut down.
Some things you have not done:
1. Adjust the valves/rockers, grind valve seats
2.Check compression in cylinders
3. Set engine timing
Also has the tractor been switched to negative ground with the 12v conversion? Or is it still positive ground with 1 wire alternator?
Have you checked for coolant leaks? Cracked head, bad head gasket, etc.
What sort of oil pressure you get?
The list is endless. Changing a bunch of parts hoping things will get better when you are not sure what's wrong is a waste of money and time.
Perhaps get a service manual. Farmall M's are a great tractor when they run right, don't get discouraged.Maybe take the cylinder head off to see what shape the things are in.
In terms of not charging, a good chassis connection is needed for electrical paths to allow charging. So be sure all mechanical points between alternator and its mounting to the engine are clean of any paint and rust. This applies to the battery cable from battery negative post to the tractor chassis also.

Also, some alternators (maybe all?) will not start charging until they are spun faster at startup. Try revving the engine to full speed and see if charging starts.

1. I did not set the valves or mess with them in any way. I also didnt pull the head since I wasnt going to mess with anything. Had I pulled the head, I probably would have taken it to get machined.

2. I did check it before, I dont recall what it was. I will double check that, specifically now since the issues.

3. That will be next step.

4. Negative ground.

5. No coolant leaks, no coolant in oil, no drips on block anywhere.

6. Have oil pressure, but dont trust the current gauge. New one is on its way.

7. I agree, Im not just throwing parts at it hoping something will fix it. Trying to be as strategic as possible. I do have a bunch of different manuals for the tractor that I use religiously. Definitely have helped me a great deal.
Ive looked at the connections, they all seems pretty good. But I guess I could probably take a grinder or some sandpaper and make the connections even better. Always better to triple check.

As far as the revving, I read that here and I tried all different RPMs and left it there for some time and nothing. When I unhook the wire and test the alternator alone, it is pumping out over 14 bolts, so its definitely creating a charge with no wire attached, only isnt when wire is attached.
Hello Greg welcome to YT! So far you have done nothing that actually harmed your tractor, so quit worrying about that. The puffs of smoke are nothing, that requires the overhaul youre planning to take care of that. Lets determine if the fact that it keeps running after you shut the ignition off is caused by actual electrical or something else. Some guys are very fearful of a shock from a stray ignition spark so I am going through the following instead of telling you to just pull out the coil wire. Get yourself a like 3 inch long piece of electrical wire strip both ends. Then pull the feed from the ignition switch off the coil. Take one end of the stranded wire and tighten it under the nut on the coil terminal. Then take the other end and make a small hook Hook the eyelet from the wiring harness on that hook. Start the engine get it warmed up as you probably had it before and then go over by the coil and disconnect the wire off of the hook. If the engine continues to run on like I did before chugging etc. then you know that something in the actual engine is causing the problem and its not electrical. This is most likely caused by hot pieces of carbon in the combustion chamber. Driving it in road gear up some hills may help this. If you have fairly long hills around start slow in road gear at the bottom and pull the throttle open and let it come up to speed. If there is more hill left idle it down and again let it pickup speed. You are trying to work the engine as hard as you possibly can. Having the idle speed of the engine set to high adds to this problem. Secondly lets check your alternator wiring. I am going to attach a link to a generic wiring diagram for a 12 V conversion. Following that diagram, see if two things seem to be correct for the diagram you have, and the wiring on the tractor. Does the large terminal wire off the back of the alternator run directly to the amp meter? Does a wire on the opposite side of the ammeter run direct to battery positive like off the starter or most Ms are equipped with a heavy duty push button switch. (my diagram does not show this type of starter switch) Your feed to your ammeter should be connected to one of the terminals on that switch that the positive battery cable is connected to. Disregard the circuits that go to the L and S terminals of the alternator on the diagram I provided, that diagram is for a 3 wire set up. The connections of the large terminal of the back of the alternator and the rest is all the same one wire or 3 wire.
Generic 5 to 12 volt conversion diagram
You don't say if you have looked for bubbles in the radiator from a coolant leak on the compression side of things that would not necessarily be a external leak. Look at the old plugs or take the ones you are running and look at them see waht they say about how it is burning in each cylinder. Black is to much fuel or oil brownish gray is what you are looking for. The valves might need some adjustment and there might just be a stuck ring that might free up with some use and seal your puffs of smoke also. With valves set and then points and timing it should run well. As for the wiring and lack of charging lets fix one thing at a time. Now for the charging it sounds like you have either a poor connection some place or a wire not connected to the correct location. And some of those 1 wire alternators need a faster speed than you can get from tractor engines.
Back in the day, it was not un-common to put stock from factory tractors in tractor pulls. Alot of guys did that. Some even took them out of the field to go to a pull, and then went back to the field with them when the pull was over.

But it's really not that way anymore. Unless a particular pull has a special class that limits the tractors in that class to be stock from factory. If not, you can bet your buttons that all the tractors there are doctored up for tractor pulling. We're talking special hitches, altered wheels, hyped up engines, and the list goes on and on. If your not playing the same game as all the others, your just wasting your time. I'm just saying. It's not like it use to be. Back when alot of guys just did it to be involved, and alot of stock tractors would show up.

Anymore, a guy kind of really has to choose how he wants his tractor to be set up. As in, set up for tractor pulling, or not. And what you'll be doing with it as the deciding factor.

Around here, you don't see any stock tractors even at the antique pulls. You show up there with one, and you'll just have your lunch eaten by the others.

I'm not trying to take the wind out of your sails on this, just kind of letting you know how it is these days. And if you got a dead cylinder until an overhaul can be done on top of it???
Redforlife, The pull I am connected with is still like that. Over the years I have put many a puller out before start of pull because they tried to sneek things past. Not doing much any more due to age connected to health. One person kept showing up with a propaine powered tractor saying it was factory and that make never made an LP tractor, especially with a 30# capper LP bottle hanging on side of tractor and no drawbar. You better not have threaded rods sticking out of rar wheels to put multiple wheel weights on, you are limited to 2 weights and factory mounting or you are out of pull. First couple of years started enforcing the rulls some tried to sneek the rods sticking so far out from wheel somebody just walking past tractor could get hurt. So they could pull they took the weights off. If not a propertyly bolted clevice on drawbar for sled hook out of pull. Good amount of pullera and nice croud watching.
I'm not sure people would even play fare in that situation. What about the things you can't see?? Like over bored sleeves and pistons?

They don't even have a class like that in pulls around here (not saying they don't where your at). About the closest thing they got to that, is at one pull they do have a 'farm' class. Kind of just an added class at that one particular pull for a few local guys. Rules are so lenient, that they haven't red flagged anybody and prevented them from pulling. Suppose to be right off the farm. But they're not. I know they throw in a few tricks and still pull. Some of the participants have even told me (me being just a spectator) what they did to thier 'farm' tractor for the pull.

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