Overheated And Running On Two Cylinders?

Sat Jul 05, 2014 8:40 pm

So I may have over-worked the ol' gal today. While cutting about 8 acres of 8-10 inch tall grass, it didnt take long to begin to dribble coolant and bog down. It seemed as moments went by it would bog down much easier as it was starting to drip coolant to the point where it finally gave out... chug, clunk, bah...dead. So thinking I over-worked it a bit, I let it cool for about 20 minutes, came back and attempted to fire it up (it just cranked and cranked and cranked with a little sputter here and there). FINALLY after an additional 10 minutes, it fired up but quickly became bogged down while cutting the grass again to the point of clunking out. After letting it cool AGAIN, I made another attempt to start and it finally kicked over but sounded like a 2-cylinder John Deere. I thought to myself "Oh great, something electrically is wrong" but then it seemed to smooth out again until I revved it up and put it under a load. Again, seeming to run on only 2 cylinders (barely). I threw in the towel and slowly limped the Cub back on 2 cylinders.

After loading the Cub on my trailer and hauling 30 minutes up the road, I was pleasantly surprised that when I made an attempt to fire it up, it immediately turned over and sounded normal! I backed off the trailer and put it under a load (PTO engaged, throttle up, 3rd gear). It sputtered again like it was only running on 2 cylinders but immediately recovered and has been running properly ever since! What gives???

Re: Overheated And Running On Two Cylinders?

Sat Jul 05, 2014 8:56 pm

Sounds like piece of trash clogging things up and it's moved on out or still swirling around to clog things up at some point again

Re: Overheated And Running On Two Cylinders?

Sun Jul 06, 2014 2:31 pm

Sounds like a coil on the way out,
Bernard,
Donegal Cub.

Re: Overheated And Running On Two Cylinders?

Sun Jul 06, 2014 8:06 pm

Ditto on the coil, and you probablyy should be cutting in 2nd gear or 1st. what size mower??

Re: Overheated And Running On Two Cylinders?

Mon Jul 07, 2014 2:25 am

Dripping coolant is pretty normal, did you just fill up the radiator?

When was the last time you did an ignition tune up and set the timing perfect? If its been a little while, I'd start there. I had a similar situation with my mowing tractor, after working for a while it just started acting up about like you describe. I found a corroded rotor and pitted points. After cleaning up these 2 problems, it mows fine. It had been about 3 years since I messed with the ignition/timing. I now have new components, but have not installed them yet. I plan to replace soon as I was not able to completely file away the pits in the points.

Do you happen to have an extra coil to try? After that, I'd move on to valve tappet clearance.

Re: Overheated And Running On Two Cylinders?

Mon Jul 07, 2014 9:01 am

I'd definitely check the coil and points, rotor, cap. Also, make sure to clean out the radiator to make sure part of it is not packed with grass, especially after mowing such tall stuff. If the engine did truly get so hot it shut down, double check your oil to make sure there's no coolant in it, as you could have blown a head gasket and lost compression on a couple of the cylinders. It doesn't really sound like this since you were able to get it to run smoothe again, but just be cautious about it. My bet is on the coil and ignition components.

Re: Overheated And Running On Two Cylinders?

Mon Jul 07, 2014 10:45 am

Right off the bat, if everything is up to snuff, you can't "overwork" a Cub. In other words if it has enough power to not stall, it will run all day with no overheating, no sputtering, no stalling, no need to "rest" every little while.

In other, other words, something's not up to snuff.

If you didn't just fill the radiator, and it's pushing coolant out the overflow, then it is definitely overheating.

If you legitimately overheated the tractor to the point where it quit, odds are you caused some internal engine damage. Burned valves, scored cylinders... Burned valves on a couple of cylinders would cause the "drops 2 cylinders after a few seconds/minutes" behavior you've described. The valves don't seal, so there's no compression.

Check the easy stuff first of course, like fuel and ignition.