49 JD-M over heating

I'm stumped a month ago I had it running just to stir the oil and warm it up, It died for no good reason and decided to never run again.....
Hmmmm This last summer I rebuilt the carb. put on new intake manafold and muffler, installed new brakes, and a host of other new parts. Including rebuilding starter, completely rewiring said machine, replaced complete ignition system. noticed that Distribitor was in backwards Ok some mush head before me didn't read the book. but it works fine. I,m making it ready for snow-plowing this winter. now said machine has decided to over heat. like 230+ within 15min. at a slight idle. Put in new radiator, Still over heats. lets see siphon feed means no pump & no thermo. still over heats. I removed the head and check water ports Notta.....put engine back together....new hoses lower tube...notta
the top of the radiator gets red hot, bottom stays cold.....using green antifreeze....so what the hells going on...perplexed tonight I ran it for 15 minutes and the same old crap 230 deg. after I shut it off I waited a couple minutes and noticed radiator was starting to warm up on the lower end. Seems like it forgot do that while I had it running HELP.....

Did you thoroughly mix the water and antifreeze? It won't circulate if it isn't premixed.
Peter

I'll second the anti freeze mix, and make sure it's not too heavy on anti freeze versus water. On my Farmall B I used -20 mix instead of -34. Also, make sure the distributor advance weights are moving and advancing timing with engine speed as it should. A stuck advance WILL make engine overheat also.

The position of the sender unit on the M is in a bad spot. Use a infrared heat gun and see if your gauge is correct. The position of the sender unit was moved on the later tractors such as the 40.

By overheating you mean boiling out of the overflow tube?

As was said those gauges aren't perfect and the probe is in a bad spot. My MT used to never get to 230 degrees on the gauge. I went as far as to get shutters for it for winter snow plowing. Ended up I had a bad gauge and/or probe. If you can put the probe in a boiling pot of water to see if the gauge is accurate or use a temp gun and see if it agrees that can help diagnose the gauge. Those tractors can run at 230 degrees all day long. When disking with my MT it would run right at 230 but never boil over.

Never had overheating in my 51 M but did find that the distributor
was put in backwards by someone before me.
I finally got into the bottom of the engine one day and with the front cylinder at TDC on the power stroke got the oil pump to mesh the gears where it was suppose to be . Borrowed a timing light
and man what a difference in the way it starts and sounds.
Nothing like a well tuned machine and was well worth the few hours it took to make it right.

Sounds like you have a few problems all tied together.

First off, M's temperature monitoring is terrible but they don't get that hot that fast. I'm sure your gauge is bad. My guess is the antifreeze wasn't premixed at a 50/50 ratio which will get you severe hot spots as well. Then there's the new manifold and muffler. With you saying the top gets red hot in 15 minutes I don't think you are exhausting the hot gasses properly.

Pull the manifold and make sure it and the gasket match the head perfectly. The others will fit but won't match. Check the inside to make sure all the holes are open with no casting blockage. Check the muffler again for a rat's nest. Do leave about 3 inches of open space in the top of the radiator. The thermosiphon won't work properly without it. One last thought I hate to even mention. Are you positive you removed the plastic insert in the radiator inlet and outlet? I have seen it done.

In the November 2019 issue of Green Magazine, the Tractor Doctor shows some of the things he did to cure an overheating M.

Get a heat gun and verify that it's really that hot first, and then check the timing, and then check for a collapsed hose, sometimes they separate and close off the flow.

The mix is at -5 deg.now I did mix it well, I was at 50/50 I'll buy a temp-gun and try it. (The muffler is new no rats) I just retimed it. and rechecked the carb settings I'll check water level and lower it if high. Thanks I'll check it all tomorrow and let you know...

Take muffler off first let it run and use a heat gun often

Thanks Guys for the help. I did buy a IR therm. and after 30 minutes of running idle in 38deg outside temp everything is below 200 on the head except for right at the guage port. 190 at the top of rediator. things are calm again in JD land....................for now. Thanks again.

This story made me think of an event where I wasted a whole lot of effort and anguish over what ultimately was a faulty oil pressure gauge.