1937 John Deere A Help!

I had the 1937 A out yesterday. Went into the barn opened the petcocks turned the fuel on and it started right up on the third turn of the flywheel like always. Drove it out of the barn, down the road about a 1/4 mile in 4th gear about 3/4 throttle. Right when I got back to the barn driveway it started to seem like it was running on only 1 cylinder and became a lot louder, with a little flame coming out of the muffler. Got it in the barn, shut the gas off and shut it down quick. When I shut the gas off it was noticeably much hotter than usual. I was dumbfounded so I started to look at few things to see if it was something simple. Right before I shut it off I noticed it had good oil pressure (between M and H). One thing I could not figure out was how hot the head was compared to the block. I could touch the block with my bare hand, but only get my hand close to head before I could feel how hot it was. Anyone have any ideas or things I can look for? Do I have an exhaust valve stuck or broken? Thanks for any insight in advance.

Its a relatively easy job to pull the valve cover and turn her over to observe valve action/operation, that may provide a clue fer sure. I believe Id do that before starting which Im sure you planned anyway.

John T

John, I was going to pull the valve cover off tonight to see if I could notice anything. Wanted to let it cool down last night. Thanks, I will let you know if I find anything tomorrow.

Is it full of water?

If the water level was low, you just cracked the head..

Are you sure "the Head was Hot", or you checked near an exhaust passage..??

From your description, it sounds like it was starving for Gas and was about to quit..

Same thing happened to me on a JD GM,it was a broken mag...retarded the spark severely. The manifold & exhaust got so hot it steamed. Fire out of the stack and missed on one.
Mag broke while running down the road. Soon as I had it rebuilt, tractor ran perfect.

Yes I forgot to mention it was full of water, and not boiling over. I am stumped. I pulled to valve cover off last night and spun the engine over, and the valves seem to be working fine. What else should I look for? Thanks in advance.

Is there any chance you recently installed antifreeze and did not pre-mix the solution BEFORE pouring it into the cooling system? See below my sign-off for an excerpt from the John Deere Model "H" Restoration Guide. (PatB)
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Antifreeze -- When adding antifreeze like the conventional green coolant such as NAPA brand prepared for NAPA by the makers of PEAK, strive to avoid having all of the antifreeze in the bottom of the cooling system. Don't just pour the antifreeze in first! Mix! Mixing antifreeze with water before pouring the mixture into the radiator will prevent development of an "antifreeze block" in your cooling system. In your JD "H" tractor, heated water will rise over unheated water because heated water has a lower "specific gravity," i.e., it is not as dense, thus lighter in weight. This "automatic circulation" does not happen until water in the lower part of the coolant jacket (engine) is heated to achieve this "less dense" state so as to rise. The specific gravity of "regular" antifreeze (such as PEAK) is 1.12. That is 12% heavier than pure water! Its density is not known to change much with temperature, and it will NEVER become less dense than pure water. So, if the lower half of your coolant jacket is filled with pure antifreeze, it just WILL NOT rise over water, meaning that you may have NO circulation! The temperature gauge reads HOT, yet the upper radiator tank is COLD. If this happens, drain, mix and then reinstall the mixture into the tractor. Caution: Never drain coolant from a super-heated engine; just shut it down and let it cool. ++++

Pat, yes the antifreeze was pre-mixed. Thank you