Plow + Bump = Stall

[HarveyCub]

Hi folks,

I've used an L54 blade on the front of my Cub LoBoy for snow clearing the past few years. With the blade down, I hit a bump in the pavement where there is a change in the asphalt connecting my main driveway and another spur off of it. Wasn't going fast and was in first gear. I certainly felt the jolt as the blade caught the lip in the road but what really surprised me was that it quickly stalled the tractor. It also took me a while to get it to start up again...while the starter button would try and get things going again, I couldn't get the engine to kick over for me without having to wait a few minutes. I've seen other topics that mentioned the tractor stalling when hitting an object while scraping or plowing, though these were often mentioned just in passing. Interestingly, this has not happened to me previously, but it happened twice in the last week.

Obviously, I'd prefer not to be stuck out there with the job only half done and now that I've experienced this, I want to be more knowledgable for next time, including this spring when I break out the moldboard plow for the first time.

Can anyone explain what it is about this jolt that causes the tractor to stall? Is there any reason to think that this would also increase the difficulty in starting the tractor up afterward?

Thanks in advance,
Harvey

[Waif]

Wild guess would be fuel related. Either carb float bounce ,or debris moved around ,or air fuel mix temporary disruption.

Hitting a bump hard is a bit like overloading a mower/ brush hog in heavy grass or brush and stalling out . Hard restart for me after, and a brief rest seems to make it easier.

[Crimson Tim]

Certainly if you hit something that arrests forward momentum, it will slow the engine down. Sometimes to the point where it can’t recover even if you make it past the actual obstruction.
I have this happen when mowing if I miss picking the deck up for a mole hill (our moles are as big as woodchucks down here...). Hitting the heap of sand is enough drag to slow the engine down. Even if momentum carries me past the sand or the mower has obliterated the heap, the engine doesn’t make enough power at the slower speed to recover with the continued load of the mower. So it stalls.
I get the impression that this is not exactly what you are talking about, though. More of just dying immediately from an instantaneous shock rather than being dragged to a halt?
My guess is that it stems from the gravity-fed fuel system. The fuel level in the carb is maintained by balancing the weight and the buoyancy of the carb float. If something upsets this equilibrium, like a sudden jolt, maybe there is a flush of fuel that floods the carb and kills the engine. Then it won’t start again until the flooding clears?

Of course, a loose electrical connection is always a possibility, but likely to either correct itself quick enough for you to keep going, or just not correct itself at all.

[HarveyCub]

Thanks Waif and Tim - interesting thoughts on the carb float. Would you say that stalling out in this situation is the expected behavior when things are all OK with the carburetor or is this a possible sign that something needs adjustment?

Without a doubt, I should avoid things that go bump in the snow if at all possible.

[eiebe]

Sounds to me likey a fuel related my 52 usually will spin a tire rather than stall, try cleaning the carb out.

[k hutchins]

It seems you have info on the possible problem with restart.
I'm gonna offer a suggestion on safety and stalling if you hit something unseen while plowing.
When l was first taught many years ago, l was told to keep my foot on the clutch pedal at all times. Not enough to ride the clutch, just cover it. That way if you do hit something and you get a sudden stop, your bodies inertia will automatically engage the clutch to prevent a stall, damage, or injury.

Just my 2 cents for safety.

[SONNY]

Two really good key points brought out here, 1) float bounce and flooded engine, = hard hot restart. 2) foot over, but NOT riding the clutch peddle will help in avoiding the kill,---unless the carb float is set too high and don't take much to slop enough extra gas over and drown the engine. When going over unknown turf for the first time a lot is trial and error,---learn as you go!--takes a while to get the feel of these little guys!, NOW moldboard plowing is a whole new can of worms if you never done it before!---Gets real interesting in some soils!--Chuggin right along--hit a tuff spot and dead cub!--usually no warning!--You cant tell whats down there until you hit it! LOL!!!! After a few passes you will plow like a pro! thanks; sonny

[Lt.Mike]

I’m going think outside the box and ask if a good jolt might have shifted the position of the run/stop switch just enough to kill the engine(?).

Another thought, why didn’t the plow trip forward? I caught it twice last night and today plowing. It tripped forward and reset each time saving me a jolt.

[John *.?-!.* cub owner]

If you had enough traction the engine stalling like that is not unusual when catching something solid. That spring is not a trip spting, it is merely a shock absorber to lessen the jolt. When an engine is stalled out suddenly like that it normally needs heavy choking to get it going, assuming it was cranking over normally.

[Matt Kirsch]

Can you please be more specific about this statement?

while the starter button would try and get things going again, I couldn't get the engine to kick over for me without having to wait a few minutes

What do you mean by "try" and "kick over?" These are not common mechanical terms and could be interpreted to mean many different things. We normally work in terms of "crank" or "turn over" where the engine is being rotated continuously by the starter, "fire" when the ignition occurs in one or more cylinders, and finally "start" or "run" when the engine begins to operate continuously on internal combustion.

When you push the starter button, what, exactly, happens?

[gitractorman]

I'm going to offer yet another possibility. This one is specific to the vintage cub /lo boy that you have and can happen because of the way the kill switch and starter button work. On those mid to late 1960s tractors, there is an on/off kill switch, then a starter button. It is possible with these tractors to push the starter button and crank the engine regardless of the kill switch position. Because of this, I'm wondering if your kill switch is getting "touchy" and the bump actually tripped the kill switch, killing the engine. With the switch now dead, you're trying to crank the engine, but it won't fire or runn because the kill switch is in the "off" position, even through it may not look like it. I'll bet that when you waited, you physically pushed the kill switch to off, then pulled it back out when you went to try starting it again. The action of you actually pushing in the switch and pulling it back out likely let it make contact again, and the treactor started. Just a hunch, but this is something that can happen.

I know this because I had something along the same lines happen on my 65 lo boy, and nearly throw me off of it. I was sitting on the tractor and my son, 4 at the time, was sittin with me on the tractor. The tractor was off and the engine was dead, but I had left the tractor in gear when I shut it down, so it wouldn't roll when we were getting on/off. While sitting there, my son reached out with his leg to push himself up onto my lap. When he pushed, he actually pushed his foot on the starter button, causing the engine to crank. Since it was in gear, ithe tractor lurched forward nearly throwing me off the back!! It wasn't till that point that I discovered that the starter will work regardless of the kill switch position. The tractor didn't start, but it rolled a couple of feet in the split second that my son pushed on the starter.

Fool luck,
Bill

[HarveyCub]

Can you please be more specific about this statement?

while the starter button would try and get things going again, I couldn't get the engine to kick over for me without having to wait a few minutes

What do you mean by "try" and "kick over?" These are not common mechanical terms and could be interpreted to mean many different things. We normally work in terms of "crank" or "turn over" where the engine is being rotated continuously by the starter, "fire" when the ignition occurs in one or more cylinders, and finally "start" or "run" when the engine begins to operate continuously on internal combustion.

When you push the starter button, what, exactly, happens?

My apologies, a bit too colloquial there. When hitting the starter button, things did crank but did not start...

[HarveyCub]

I'm going to offer yet another possibility. This one is specific to the vintage cub /lo boy that you have and can happen because of the way the kill switch and starter button work. On those mid to late 1960s tractors, there is an on/off kill switch, then a starter button. It is possible with these tractors to push the starter button and crank the engine regardless of the kill switch position. Because of this, I'm wondering if your kill switch is getting "touchy" and the bump actually tripped the kill switch, killing the engine.
Bill

That was something I learned on my machine as well, but hopefully that this isn't the case in this scenario. Had the hood off last month and I replaced both the switch and the starter button.

[ricky racer]

Avoid the possibility of stalling or damaging your tractor by doing this:

viewtopic.php?f=1&t=48323&hilit=snow+plow

[Matt Kirsch]

Ok good. That rules out the main starter cables and the starter itself.

Did you check for spark? Did you try giving it some choke while cranking?

Did this bump actually stop the tractor as in running into something solid, or did it just jolt the tractor? If the latter I would suspect loose wiring.