M Governor/Driving Down Hill

So I've been on a couple tractor rides as of late and I'm having an issue with the tractor speeding way up when going down hill. I have noticed in 5th gear the governor and motor seem to have some effect
in slowing the tractor down going down hill, but usually I'm pumping my brakes and trying not to hit the guy in front of me. Mind you I try to leave a large gap before heading downhill. As for going
uphill I have almost no issues, you can hear the governor open right up and away we go. I have never experienced any "surging" in the engine, as mentioned in the service manual, at idle or any other
time.

I have a Farmall M, wide front with one set of rear wheel weights (no fluid in the tires as they are 3 weeks old).

Here's what I've done:
1. We checked the compression on the engine this past winter and it tested a couple pounds below what it should be in each cylinder
2. Rebuilt the carb this past winter and then set it based on what I read in my service and owner's manual.
3. I have checked and rechecked to make sure the tube from the governor to the carb is hooked up correctly.
4. I opened up the governor and all the parts appear to be moving freely and I didn't notice any slop in anything other than a bearing on the center horizontal shaft, with the bearing being towards the rear (carb side), seem to slid a little on the shaft.

I'm at a loss as to what to do to help correct this situation. My guess is it's probably time to rebuild the engine. Any other thoughts or things I may have overlooked? Thanks

I may back the throttle off on my tractors going down hills, sometimes to an idle.

(quoted from post at 13:28:13 07/17/17) I may back the throttle off on my tractors going down hills, sometimes to an idle.

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I tried that with little success.

My M behaves very similar. I really think it is all in the governor.

You back the throttleoff going down hills You dont want to over rev the engine with no load.

I've never tried going down hill at full throttle, but I have upped it a little off idle to see if that would make a difference, but neither setting seemed to do much.

Do you close it clear down to idle if needed?

OK , so your going down a hill in fifth gear and it will not hold back . So you now think the problem is the Gov. ????? You LOOKED INSIDE THE GOV and everything LOOKS ok . Well lets back up and look again , does the spring fit loose in the two arm holes ?????? I'll bet it does as most gov.'s i have been into i find that the BUSHINGS are GONE , yep there is suppose to be a harden bushings filling up that big hole where the spring goes and over time they fall out . when the spring fit's the way it is suppose to fit it helps shut down the gov. and hold the engine better at idle , it also helps on Gov response . . BUT IT IS NOT a Jake brake and the old M engine or any other engine is not going to give much hold back in road gear . SO for you young pup's that have never seen the sign's along side the old goat paths before a hill that warned truckers of a hill that read USE LOWER GEAR to descend a hill . even in forth gear the engine is not going to hold you back that much going down the hill . If it was a diesel it would be worse as diesels do not have the hold back as a gas engine that is why trucks of today have what is called a Jake brake or engine brake for hold back going down a hill . So yes you are going to have to use the brake pedals to slow you down . If you lived around here and have hauled loads behind a tractor at some point in time you have had smoke coming off the brakes trying to hold a load back and slow down . Paint on brake drums does not last long around here if you drive one on the road.

Also this brings back a memory from years back one mid Sept Saturday while harvesting taters . Someone found a need for my uncles one year old 706 D and made it vanish and we needed another tractor while we waited on the new replacement the dealer loaned a S/M with wide ft for use to use . it was getting the job done fine at the home farm where ya never got much over forth gear heading back to the fields empty and never above third loaded with eight to maybe ten ton of taters . But we had moved up the road about a mile and from the fields we were now in it was DOWN hill to the main farm . Not real back but still down hill , BUT once you went past the lane back to the farm by fifty feet or so IT really went down hill big time and at the bottom of that hill was a set of rail road tracks then it went back up hill for a bit then back down hill to a stop sign at the state road and then down hill once again down into the swampy creek bottom . I got to the farm around 1 in the afternoon as i had my reg job that was a half day on Sat. and i caught a ride to the field in one of the old trucks we used also to haul taters with . The M was setting there loaded and i went to get on it and my Uncle yelled at me and said DON"T USE road gear . Well them words fell on deaf ears as i pulled out of the field and turned on to the side dirt road and headed for the county road . The S/M did not have enough snort to drag the load up the little up grade in third and i had to back down and use first to get up on the county road and do most of the steering with the brake , once up on the county road i got it up in forth and was thinking this sucked and popped it into fifth at about half throttle thinking yea this is good . Till i started gaining speed and i shoved the throttle back and was still gaining speed and i start pushing on the BRAKES and PUSHING and PUSHING and we ain't slowing down and flew past the lane and down over the steep hill we went how fast i was going i have no idea but i am sure if it had wings we would have left the ground , when we hit the railroad tracks the ft end went air born high enough that the draw bar pin dug into the tar and gravel and bent back up over the next hill and thru the stop sign and down the next hill and down into the swampy area and made the slight turn thru the bridge . And got it stopped before the next hill up . Brakes smoking drums burnt black and me shaking . and taters scattered at the railroad tracks . I got turned around and headed back up out of the swamp and made it to the bottom of the big hill heading back to the farm and the S/M did not have enough to pull the hill in first , One of the locals stopped to see if he could help and he had to get my Uncle to pull the 806 off the harvester and bring it down to pull the load up the hill , Lets just say he was just a tad upset with me . Now why that tractor did not throw a rod or bust in half when i hit the tracks i have no idea how i lived thru it is something shell we say was a learning exp. Never did find my hat.

Good story, glad you survived!

The main thing that's at work is a mechanical "war" between the "motored" engine's overrunning torque and the restriction of the air attempting to suck past the closed throttle blade. The governor can only attempt to move the linkage to close the throttle blade, and once that travel is maxed out, there is no more.

On a lower compression engine 6:1 which I think is pretty common for stock Farmall, there isn't as much air trying to pull past the blade.

Most modern truck engines starting with TBI fuel on up are in the 8:1 range or more. So that's 33% more air it would be trying to pull in, enhancing the engine braking.

As stated above, a diesel has no throttle blade (its speed is dependent on injection timing and volume) so no intake restriction at all.

Rebuilding valves, piston rings and bores can only help, but I would not expect a massive improvement in braking performance. Using the lower gear is best as it gives an additional geared mechanical advantage to the throttle blade's restriction.

Yes, I'm only 38 (which is considered young by some) and I've only been in the antique tractor game for about 15 years. I'm not a farmer and don't have very many family members in agriculture. I started out playing with green tractors, but just sold off my last one. I have a Allis WD45 and this Farmall M. The WD45 is more for sentimental value and the Farmall is my "play" tractor. Since I don't have the deep history or experience as some of you have I come to places like this for information.

First I don't expect the tractor to be able to hold back itself plus a wagon of tators going downhill in 5th gear. Yes I did notice the spring was a little loose and I made a slight adjustment to the upper adjustment bolt and it took out the little bit of looseness that was there. I didn't know there is supposed to be bushings in there but I will look in my parts book and investigate further.

Maybe I'm expecting too much out of the governor? I don't know. I'm just basing things off of the fact on one of the rides I was in a group with other M's & super M's and as we're going down hill they all seem to stay the same speed and evenly spaced and I was catching up to them rather quickly and pumping the brakes. I asked them if they had to do the same with the brakes and they said no. So here I sit and wonder...

I've never driven a gas engined tractor that would hold itself going down any sort of hill. Don't know what magic these "other" tractor guys are using, but I suspect they're lying to you. They probably ride their brakes down the hill.

Why are you "pumping" the brakes? They're not hydraulic, so literally pumping them does no good. Apply and hold until you've slowed down to where you want to be, then let go. If you don't feel the brakes are slowing you down adequately, then you need to work on the brakes. They should easily slow the tractor down on a hill.

I pump them to prevent overheating and burning the paint off. I can push them and they'll bring me to a stop on a hill.

Yeah, like I said maybe I'm just expecting too much.

The vacuum being created when the throttle is closed (assuming he throttles down) is (as you point out) not sufficient to limit
down hill speed on the hills you are encountering. Few if any IH Letter or 3 digit tractors with disk brakes have the paint on the
housing. Rolling 4% grades will require no brakes, but that is what they are there for. Jim

If you have a good tight engine with higher compression it will hold back a little better . My own s/MTA willl not hold back well on our hills and braking is required . Now as for the bushing , when i am fixing one up i have to make the bushings and press them in and you have to be vary care full not to break the cast arms . I have a guy that works on clocks and watches make them on his small machines out of bronze . I fixed his S/MTA back many years ago and it made a new tractor out of it.. The hole for the spring has to be kept as tight as possible and both sides of the spring hole has to chamfered due to the bend of the spring .

(quoted from post at 01:53:09 07/18/17) If you have a good tight engine with higher compression it will hold back a little better . My own s/MTA willl not hold back well on our hills and braking is required . Now as for the bushing , when i am fixing one up i have to make the bushings and press them in and you have to be vary care full not to break the cast arms . I have a guy that works on clocks and watches make them on his small machines out of bronze . I fixed his S/MTA back many years ago and it made a new tractor out of it.. The hole for the spring has to be kept as tight as possible and both sides of the spring hole has to chamfered due to the bend of the spring .

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Parts manual doesn't show or call out any bushings there. I also checked the service manual and nothing is mentioned about bushings on either end of the spring or to replace a bushing on either end of the spring if worn or missing.

That's because there isn't any bushings there. Not sure what TV is talking about, but I'm sure he will insist they are there.