How to Choose Excavator Thermostat?
Sep. 08, 2025
Which cooling thermostat to use - JD ? - TractorByNet
Back again with yet another question. I am just about finished doing my pre-season maintenance on the above tractor. I am thinking of changing out the engine coolant thermostat. According to previous owners notes it has been in there for a 'long' time. The parts book shows three thermostats - 180°, 192° and a 205°. The service manual says: "Thermostat for normal operating conditions opens at 180°" and "Thermostat for light operating conditions opens at 194°" NO definitions given as to what is a NORMAL or LIGHT operating conditions. I have tried talking to JD parts and they just say "What one do I want?" I don't know until I get some definitions. I can't trust what is currently in there as it has been changed out and IF the wrong part was put in then I will just be copying a previous mistake. I don't know if diesel engines need to be operated at a higher or lower temp vs gas engines. Perhaps I am just overthinking it (one thing I have learned is mistakes cost money) so I would rather make the best/correct choice and put in the RIGHT part. So, any thoughts or ideas on this would be most helpful and appreciated. THANKS to ALL for any and all thoughts given.
Where are you located? What type of low winter temps to you typically experience and what type of dummer high temps? How do you use your tractor?
In my part of the lower mid-west, almost in the mid-south, I would opt for the 180 if I had your tractor. Personally I would not consider the 205 thermostat for any part of the country.
Sometimes, you have a fan clutch or an electric fan that is tuned to your thermostat temp opening. If so, try to find out when the fan kicks on and that's when you want the thermostat to open.
If you have a direct coolant fan, I'd probably opt for the 192 unless otherwise dictated by the OEM. It is generally the 'go-to' T-Stat temp for most OEM applications on most road vehicles. Not all, certainly. Most. Some tractors call for 180 but I'm not wild about those. Most engines run best right at 194 degrees water temp. Gaskets, seals, hoses, bearings, the metal (rings, etc) itself seems to like that temp about the best. On modern vehicles.
My son went to school in NC, I am in and from SE Missouri. I have driven through several areas of East TN, some beautiful country out there, if less than great roads.
With low 90’s for highs in the summer, I would probably go with the 19x thermostat. My highs in summer will often run 10-15+ degrees hotter than yours. Realizing that the set temp is approximately where the thermostat begins to open to allow coolant to circulate. Under heavy work conditions, and some of those hillsides in E TN qualify for heavy load condition without much added to the work load. I would not use a 200+ thermostat.
Back again with yet another question. I am just about finished doing my pre-season maintenance on the above tractor. I am thinking of changing out the engine coolant thermostat. According to previous owners notes it has been in there for a 'long' time. The parts book shows three thermostats - 180°, 192° and a 205°. The service manual says: "Thermostat for normal operating conditions opens at 180°" and "Thermostat for light operating conditions opens at 194°" NO definitions given as to what is a NORMAL or LIGHT operating conditions. I have tried talking to JD parts and they just say "What one do I want?" I don't know until I get some definitions. I can't trust what is currently in there as it has been changed out and IF the wrong part was put in then I will just be copying a previous mistake. I don't know if diesel engines need to be operated at a higher or lower temp vs gas engines. Perhaps I am just overthinking it (one thing I have learned is mistakes cost money) so I would rather make the best/correct choice and put in the RIGHT part. So, any thoughts or ideas on this would be most helpful and appreciated. THANKS to ALL for any and all thoughts given.
Where are you located? What type of low winter temps to you typically experience and what type of dummer high temps? How do you use your tractor?
In my part of the lower mid-west, almost in the mid-south, I would opt for the 180 if I had your tractor. Personally I would not consider the 205 thermostat for any part of the country.
Back again with yet another question. I am just about finished doing my pre-season maintenance on the above tractor. I am thinking of changing out the engine coolant thermostat. According to previous owners notes it has been in there for a 'long' time. The parts book shows three thermostats - 180°, 192° and a 205°. The service manual says: "Thermostat for normal operating conditions opens at 180°" and "Thermostat for light operating conditions opens at 194°" NO definitions given as to what is a NORMAL or LIGHT operating conditions. I have tried talking to JD parts and they just say "What one do I want?" I don't know until I get some definitions. I can't trust what is currently in there as it has been changed out and IF the wrong part was put in then I will just be copying a previous mistake. I don't know if diesel engines need to be operated at a higher or lower temp vs gas engines. Perhaps I am just overthinking it (one thing I have learned is mistakes cost money) so I would rather make the best/correct choice and put in the RIGHT part. So, any thoughts or ideas on this would be most helpful and appreciated. THANKS to ALL for any and all thoughts given.
Sometimes, you have a fan clutch or an electric fan that is tuned to your thermostat temp opening. If so, try to find out when the fan kicks on and that's when you want the thermostat to open.
If you have a direct coolant fan, I'd probably opt for the 192 unless otherwise dictated by the OEM. It is generally the 'go-to' T-Stat temp for most OEM applications on most road vehicles. Not all, certainly. Most. Some tractors call for 180 but I'm not wild about those. Most engines run best right at 194 degrees water temp. Gaskets, seals, hoses, bearings, the metal (rings, etc) itself seems to like that temp about the best. On modern vehicles.
Where are you located? What type of low winter temps to you typically experience and what type of dummer high temps? How do you use your tractor?I am located in East TN. Typical summer temps are the lower 90's. The tractor is used to 'maintain' several flat pastures 3 ~ 4 times during the summer months. Each mowing usually takes about 5~7 hours. Come the fall the tractor is put back in the shed, battery tender attached and the engine oil/filter is changed. NO starting/using during the winter months. Hope this helps.
In my part of the lower mid-west, almost in the mid-south, I would opt for the 180 if I had your tractor. Personally I would not consider the 205 thermostat for any part of the country.
Sometimes, you have a fan clutch or an electric fan that is tuned to your thermostat temp opening. If so, try to find out when the fan kicks on and that's when you want the thermostat to open.The fan is direct driven with a drive belt - no thermostat or anything else. Engine running - fan running. Please see the post above for the usage and running times if you need that info. As I stated in the original post the OEM is very vague about their recommendation. So, your call as I understand it, is for using the 194° thermostat.
If you have a direct coolant fan, I'd probably opt for the 192 unless otherwise dictated by the OEM. It is generally the 'go-to' T-Stat temp for most OEM applications on most road vehicles. Not all, certainly. Most. Some tractors call for 180 but I'm not wild about those. Most engines run best right at 194 degrees water temp. Gaskets, seals, hoses, bearings, the metal (rings, etc) itself seems to like that temp about the best. On modern vehicles.
I am located in East TN. Typical summer temps are the lower 90's. The tractor is used to 'maintain' several flat pastures 3 ~ 4 times during the summer months. Each mowing usually takes about 5~7 hours. Come the fall the tractor is put back in the shed, battery tender attached and the engine oil/filter is changed. NO starting/using during the winter months. Hope this helps.
My son went to school in NC, I am in and from SE Missouri. I have driven through several areas of East TN, some beautiful country out there, if less than great roads.
With low 90’s for highs in the summer, I would probably go with the 19x thermostat. My highs in summer will often run 10-15+ degrees hotter than yours. Realizing that the set temp is approximately where the thermostat begins to open to allow coolant to circulate. Under heavy work conditions, and some of those hillsides in E TN qualify for heavy load condition without much added to the work load. I would not use a 200+ thermostat.
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