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Early Farmall M Thermostats?

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EmanM18

New User
Hi! I have a 1940 Farmall M that is showing symptoms of a stuck thermostat (coolant in the top part of the radiator heats up quickly but the water temp gauge never gets past "cold"). I was wondering if the early Farmall M's even utilized a thermostat? That might be a stupid question but I'm not super knowledgeable about these engines. I know that some things are different on the early M's like the radiator being non-pressurized so I wasn't sure if that made any difference with other components like the thermostat.
 
EmanM18 said:
Hi! I have a 1940 Farmall M that is showing symptoms of a stuck thermostat (coolant in the top part of the radiator heats up quickly but the water temp gauge never gets past "cold"). I was wondering if the early Farmall M's even utilized a thermostat? That might be a stupid question but I'm not super knowledgeable about these engines. I know that some things are different on the early M's like the radiator being non-pressurized so I wasn't sure if that made any difference with other components like the thermostat.
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They should all have a thermostat, even the non-pressurized ones. Farmall Cubs have a non-pressurized cooling system, and they have a thermostat.
A quick and easy way to check if your thermostat is working is to start the tractor cold, then open the radiator cap. With a functioning thermostat, there should be no coolant flow at all. Then, when the tractor warms up, you should start to see coolant circulating in the radiator.
 
Ok. I have a new question then. My tractor will not be put to hard work or ran for long periods of time so would it hurt anything if I just don't worry about the stuck or non existent thermostat or would it be better if I put one in it still?
 
I don't have one, but I understand M & H have large bypasses around the thermostat so it takes a lot of work to make the thermostat open. Someone correct me if I'm wrong.
 
Absent Minded Farmer said:
I'd change out the thermostat & give the cooling system a vinegar flush. That'll keep your system happy for a long time, with limited use.

Also, you may want to check the new thermostat for function by putting it in some boiling water to see if it opens. On great occasion, they don't.

Mike
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Thank you! It's a shame that new parts don't work a lot of the time. Everything is just so cheaply made nowadays.
 
Yes, replace or put in a new thermostat.

Engine wear is greatly accelerated by continuous cold engine operation.

Another important point with that is once you get your thermostat replaced, once in a while get the tractor nice and warm somehow. Whether driving down the road or pulling an implement, these tractors are meant to work and will run better if they do.

Do you by chance have a coolant heater on your tractor?

Please keep us updated if you do change your thermostat.
 

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EmanM18 said:
Ok. I have a new question then. My tractor will not be put to hard work or ran for long periods of time so would it hurt anything if I just don't worry about the stuck or non existent thermostat or would it be better if I put one in it still?
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Absolutely replace the thermostat! Running it lightly loaded and without a t'stat will keep it running cold which causes condensation and unburned fuel to accumulate in the crankcase which in turn causes rapid buildup of sludge and acid,

Also......the engine will simply run better (and use less fuel!) when operated at design temperature.
 
Powered By IH said:
They should all have a thermostat, even the non-pressurized ones. Farmall Cubs have a non-pressurized cooling system, and they have a thermostat.
A quick and easy way to check if your thermostat is working is to start the tractor cold, then open the radiator cap. With a functioning thermostat, there should be no coolant flow at all. Then, when the tractor warms up, you should start to see coolant circulating in the radiator.
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All cubs had a thermosyphon cooling system, no thermostat. Some of them had a pressure system but still no thermostat.
 
I agree with 560Denis but instead of replacing it just leave it out if your not going to run it in the winter.I left mine out because I bought a new one but it still ran on the warm side and running cooler only adds to the life of the engine.
 
Farmall M 248 said:
I agree with 560Denis but instead of replacing it just leave it out if your not going to run it in the winter.I left mine out because I bought a new one but it still ran on the warm side and running cooler only adds to the life of the engine.
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Just by chance did you put a thermometer in the radiator and measure what you were getting ! Just curious ?
 
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