Farmall M Surging Issue

[farmall_fiend]

Hey Everyone, I have a 1951 Farmall M and it has developed an issue where it surges upward in RPM occasionally. It appears to do it whenever I hit a bump/hole with the front wheels.

There is a loader on the tractor and I also noticed that it happens when pushing snow. It will push the snow just fine but when the front wheels reach the snow pile it will usually rev up as well.

I thought there might be a broken spring inside the governor that was allowing the RPMs to surge but after removing the side cover that doesn't appear to be the issue.

Any ideas?

Thanks!

 

[ih560]

It sounds like the linkage from the governor to carb might be binding and causing the throttle to jerk instead of coming in smooth. Does it usually accelerate smoothly?

 

[farmall_fiend]

Yeah thats possible, I can do some checking on that tonight. It normally accelerates pretty smoothly though.

 

[ih560]

I'm not saying this is for sure your problem, but if have seen the tube get gunked up and cause issues. I have also seen where you need to adjust the tube so that the throttle shaft could rotate smoothly. When first got my 450 it would rev up with the throttle but then not want to come back down to an idle. I loosened the bolts securing the tube on both ends and move it a little and let it settle in a nice neutral position. After that, everything was fine, and throttle worked correctly.

 

[rustyfarmall]

Quite possibly the governor is just flat worn out. If it just recently started doing that, and you have not touched it, then the linkage between the carb and governor is not at fault.

 

[the tractor vet]

Myself i would start by going over everything from the hand throttle all the way down and into the Gov. I can almost guarantee thqat the two harden bushing in the two arms inside the gov where the spring is are GONE , history . NO you can not just run out and BUY them . I make them out of bronze and machine for a press fit ( notice i said PRESS fit not just drive them in ) ya drive them in you will break the arms ( don't ask) once this is done then i do a total gov adjustment . I fix all the ware points from the steering wheel down to the gov. make the bushings and size to fit for free floating of the spring but still do it's job of forcing the engine back to ideal . A sloppy spring will not allow the gov to work as it should. and i install a new spring while i am in there.

 

[farmall_fiend]

I checked things over this weekend and found a couple issues. With the governor cover off I could see that the spring was loose when the throttle was set to idle and as mentioned correctly above the bushings were gone. I assume the spring should still be extended somewhat so it is at least tight and not flopping around when set to low idle.

I also noticed that when the throttle is set to wide open the max throttle adjustment screw was about 1/4" away from touching off. I adjusted that screw outward so that it touched off. I then put the cover back on and it does not seem to surge anymore so thats good.

I think my next step will be to get a new spring and also try to fab up some new bushings.

Thanks everyone!