Farmall 140 Engine Trouble

[Asar2525]

Hi Everyone,

First post here! My father's old Farmall 140 has been having issues lately. I used it to brush hog about 8 acres and it did great, then I drove it home. One stretch of this road is a VERY bumpy dirt "road" that is downhill the whole way. After I got off the hill the tractor was running VERY poorly. When it was under load (uphill or high gear) the tractor would sputter and lose power. It also had a skip at idle. I pulled over and cleaned out the radiator, figuring maybe the huge amount of goldenrod pollen I had driven through clogged it and was causing the tractor to overheat but that didn't help. I limped home with almost no power and since then have: Cleaned the carb twice, cleaned the lines leading to the carb, and the screen in the bottom of the gas tank. I thought it was a gas flow issue, but that didn't help. We checked the distributor, plugs, and plug wires and all of those seem good. The only other two things we can think of are the governor, or the coil. We recently (<50 hours ago) did a 12v conversion and are wondering if maybe it damaged the ignition coil? Any thought or suggestions would be helpful before we start tearing apart the governor? Any way to test an ignition coil?

 

[Norm W]

Sounds like it is running lean. When you said you cleaned the carb, did you clean all the passages? Running down hill with a low fuel level, you had finished brush hogging, can loosen rust in the tank and get it in the carb. Usually it is a very fine rust that goes right through the screen. One old trick is to back out the high speed needle valve a couple of turns with the engine at full throttle and pull the choke out and in quickly. It will sometimes clear the passages. Then reset the needle valve. If you replaced the coil with a 12 volt coil or used a ballast resister with a 6v coil that shouldn't be the problem. If the plug wires are suspect, mist some water on the while the engine is running. If it is at night you should see some "Fireworks" if they are bad. Go for the simple stuff first.

 

[DJ54]

I'll have to agree, sounds like it's running lean.

Unhook the fuel line at the carb., and make sure you have a good stream of fuel. If you do, while the line is off, remove the elbow going into the carb. the fuel line attaches to. It should have a fine mesh filter screen (pictured below) that may be plugged. Some carb cleaner spraying back through the mesh, followed by some compressed air usually cleans them right up.

If it's still not running right, the next item to plug would be the discharge nozzle. It will need to be removed, and check the tiny cross drilled holes to see if any may be plugged.

 

[Asar2525]

Thank you both for the responses. I found the culprit in the carburetor, the needle valve was gummed up, and while I did clean the port when I cleaned the carb, I failed to clean the needle valve itself! Doh.

Now we have a new issue. My father decided to play around with the governor-carb linkage before I found what was causing it to run lean, and now the throttle response is not working as it should. Basically we have two speeds, idle or full open. We adjusted it according to the shop manual we have, which says to open the throttle completely, disconnect the clevis, and adjust the linkage until the pin goes in freely while the rod is pushed fully open at the carburetor. Any tips for adjusting the governor? This was working properly before adjusting it according to the manual, but we're unable to see what the length was.

 

[Norm W]

In a governor, the hand throttle spring is balanced by fly weights spinning at engine speed. If the engine slows, due to a load increase, the spring pulls the throttle open to increase power. It sounds like the fly weights have become disengaged inside governor. That would give closed or wide open throttle but no control. That probably occurred when the linkages were disconnected. It's been a while since I've had one apart. You might want to check a service manual for the easiest way to check out the governor.

 

[DJ54]

You left one thing out in your description of adjusting the linkage. Both the rockshaft arm, and rod should be pushed back towards the carb., then adjust the clevis so the pin slides through freely. Pushing the rockshaft arm back, puts the fork inside the governor itself up against the thrust washer it rides on, and removes any slack. If you adjusted it without doing this, it would allow some slop between the fork, and thrust bearing, and possibly cause your problem.

If you did push the arm back, then you may have other problems. I have had too small of a cotter pin in the rod, and it let it back out far enough to bind on the block.

And it may be possible, that when previous adjustments were made, it let the thrust bearing separate enough, that if the cage that holds the small ball bearings has disintegrated, they may have dropped out.

I would try readjusting it again, with both the rocker arm, and rod pushed back, and go from there.

 

[Asar2525]

DJ54, by pushing the rocker arm back, do you mean the arm coming from the governor that the clevis attaches to? If so, it is pushed back as far towards the carb as it can go while the throttle is wide open, then the linkage is adjusted. I'm beginning to think it is something inside the governor which is causing the problem. Should be a fun weekend project if playing with this linkage doesn't pan out.

Edit: We do have an IH service manual for the tractor which does include a section on the governor. However, I get nervous while working on anything with small springs.

 

[DJ54]

Yes, that's the one. I've noticed a tad bit of slop forward one a couple of mine when adjusting the rod. It only takes my left ring finger to make sure the rockshaft gets the fork back against the thrust bearing, via the cross shaft into the governor.

The only springs would be the one that holds the fork back against the bearing, inside the governor, and the bumper spring to keep the governor, from hunting. Slim to none chance they will come out.

So if you are adjusted properly, I'd have to guess the thrust bearing may have separated enough, that if the cage holding the tiny ball bearings has disintegrated, and dropped out, as mentioned above.

 

[Asar2525]

Okay, I'll tear it apart this weekend and let you all know what I find.