thermostat info please

yugo · May 28, 2006

I've got a Jimna tractor with a Y385 engine. With this Kansas weather (90+ degrees, lately) and mowing taller grass (conserving fuel), the tractor seems to be running a little on the warm side. I've been monitoring engine temp with "ray gun" thermometer. The cylinder head temp is running about 193 degrees, top of the radiator 186 degrees, and bottom of the radiator about 167 degrees. I also noticed the oil temp is approximately 187 degrees. I'd like to change thermostats in, and at least drop her down 10 degrees. Any ideas on what automotive thermostats would fit this tractor. I'd appreciate any information. You know how those parts guys are - don't have a listing for Jimna! Any comments would be appreciated. Thanks - Yugo

yugo · May 28, 2006

I've got a Jimna tractor with a Y385 engine. With this Kansas weather (90+ degrees, lately) and mowing taller grass (conserving fuel), the tractor seems to be running a little on the warm side. I've been monitoring engine temp with "ray gun" thermometer. The cylinder head temp is running about 193 degrees, top of the radiator 186 degrees, and bottom of the radiator about 167 degrees. I also noticed the oil temp is approximately 187 degrees. I'd like to change thermostats in, and at least drop her down 10 degrees. Any ideas on what automotive thermostats would fit this tractor. I'd appreciate any information. You know how those parts guys are - don't have a listing for Jimna! Any comments would be appreciated. Thanks - Yugo

Keoke · May 28, 2006

Yugo, most modern auto and tractor stats are set at 195 degree's.
The old cars ran at 160 to 180 but this is no more. You will get better fuel use (vaporization) at 195 then at 180 and less fuel and water condensation in your crankcase with the higher stat setting as well.
Don't worry about seeing 190/195F at cyl head, this is very normal and shows stat is doing it's thing.
The boiling point of water goes up 2.7 degree's for every pound of radiator cap pressure applied. Also, coolant (ethylene glycol) has a higher boiling point then water. However, coolant does not transfer heat as well as water so too much coolant can make an engine run hotter then it wants to.
Another point on stats, taking a stat out all together will increase the flow rate (speed) of water thru the radiator where most of the heat is loss. The size of opening on many OEM stats is considered to be a tuned orifice for controlling water flow speed through the system. Best to stay with factory specs here.

cheers,

Keoke · May 28, 2006

Yugo, most modern auto and tractor stats are set at 195 degree's.
The old cars ran at 160 to 180 but this is no more. You will get better fuel use (vaporization) at 195 then at 180 and less fuel and water condensation in your crankcase with the higher stat setting as well.
Don't worry about seeing 190/195F at cyl head, this is very normal and shows stat is doing it's thing.
The boiling point of water goes up 2.7 degree's for every pound of radiator cap pressure applied. Also, coolant (ethylene glycol) has a higher boiling point then water. However, coolant does not transfer heat as well as water so too much coolant can make an engine run hotter then it wants to.
Another point on stats, taking a stat out all together will increase the flow rate (speed) of water thru the radiator where most of the heat is loss. The size of opening on many OEM stats is considered to be a tuned orifice for controlling water flow speed through the system. Best to stay with factory specs here.

cheers,

greg_g · May 28, 2006

The -T variant of the Y385 diesel is set up to operate most efficiently in a tractor at 80 degrees Centigrade (176 Fahrenheit). Diesels will also have a slightly different heat signature than gasoline, so be sure you understand what you're seeing with that temperature probe. I don't recommend you use anything other than an 80C (or F equivalent) thermostat in Kansas.

Besides some Jinmas being fitted with the wrong thermostat in the first place, the next most common reason for excess heat a lack of air flowing through the radiator. If your engine has the correct thermostat and STILL runs too hot, some of the things folks have done to improve airflow include
1. get a shorter battery
2. put 2" suction hose on air intake to breath from behind the radiator. I ran a 36" section along the side of the engine and fuel tank. It sucked cool air from down around my left shin.
3. clean out the radiator fins - especially behind the battery. I'd advise removing the radiator to do this. Chances of destroying the fins are reduced if you can actually SEE what you're doing.
4. make sure the fan is completely encased within the fan shroud
in addition to optimizing airflow,
5. make sure you have the right radiator cap, it's a real low rating (~4 psi). Closest I could find was an aftermarket 7 psi.
6. use minimum 50/50 anti-freeze/coolant mix (max 70/30)
7. check water temp with your probe to establish how accurate the Jinma temp gauge is
8. if you're using regular old engine oil intended for gasoline engines, switch to a 15W40 that is approved for diesels.

//greg//

greg_g · May 28, 2006

The -T variant of the Y385 diesel is set up to operate most efficiently in a tractor at 80 degrees Centigrade (176 Fahrenheit). Diesels will also have a slightly different heat signature than gasoline, so be sure you understand what you're seeing with that temperature probe. I don't recommend you use anything other than an 80C (or F equivalent) thermostat in Kansas.

Besides some Jinmas being fitted with the wrong thermostat in the first place, the next most common reason for excess heat a lack of air flowing through the radiator. If your engine has the correct thermostat and STILL runs too hot, some of the things folks have done to improve airflow include
1. get a shorter battery
2. put 2" suction hose on air intake to breath from behind the radiator. I ran a 36" section along the side of the engine and fuel tank. It sucked cool air from down around my left shin.
3. clean out the radiator fins - especially behind the battery. I'd advise removing the radiator to do this. Chances of destroying the fins are reduced if you can actually SEE what you're doing.
4. make sure the fan is completely encased within the fan shroud
in addition to optimizing airflow,
5. make sure you have the right radiator cap, it's a real low rating (~4 psi). Closest I could find was an aftermarket 7 psi.
6. use minimum 50/50 anti-freeze/coolant mix (max 70/30)
7. check water temp with your probe to establish how accurate the Jinma temp gauge is
8. if you're using regular old engine oil intended for gasoline engines, switch to a 15W40 that is approved for diesels.

//greg//

JohnS · May 30, 2006

What Greg said. If you have been mowing for some time, and the temp has been steadily rising, most likely a clogged radiator. Here is what I did to my Jinma: web page

PS: I do run a higher temp t-stat, without issue, but running under NY weather. I also don't have any engineering data that says the higher temp is good or bad, for the engine. Take the t-stat with you, to get the right dimentional one.

JohnS · May 30, 2006

What Greg said. If you have been mowing for some time, and the temp has been steadily rising, most likely a clogged radiator. Here is what I did to my Jinma: web page

PS: I do run a higher temp t-stat, without issue, but running under NY weather. I also don't have any engineering data that says the higher temp is good or bad, for the engine. Take the t-stat with you, to get the right dimentional one.

yugo · Jun 11, 2006

Update on thermostat (with a laugh). What we found by measuring the old thermostat, is that it is very comparible to a 350V8 Chevy. The original thermostat had 70C marking on it (approx 158 F). It also had a weep hole. We are a firm believer in weep holes. The new stat did not have one, but we drilled an 1/8" weep hole in it. A new fan belt, and a new 50/50 antifreeze and water mixture, and we feel like we are good to go again. WRONG Approx 89F temp outside, temp on guage started at the low side of the 80C mark, and an hour later the highside of the 80C mark. Here's the laugh - Greg and John S. - I do a lot of preventative maintenance on this tractor, everything looked good - including the radiator- but after reading your responses, I flushed the outside of the radiator, and lo and behold, I have lower temps after 2 hours of running tractor. (lower side of 80C mark!) Thanks for the good suggestion. Yugo

yugo · Jun 11, 2006

Update on thermostat (with a laugh). What we found by measuring the old thermostat, is that it is very comparible to a 350V8 Chevy. The original thermostat had 70C marking on it (approx 158 F). It also had a weep hole. We are a firm believer in weep holes. The new stat did not have one, but we drilled an 1/8" weep hole in it. A new fan belt, and a new 50/50 antifreeze and water mixture, and we feel like we are good to go again. WRONG Approx 89F temp outside, temp on guage started at the low side of the 80C mark, and an hour later the highside of the 80C mark. Here's the laugh - Greg and John S. - I do a lot of preventative maintenance on this tractor, everything looked good - including the radiator- but after reading your responses, I flushed the outside of the radiator, and lo and behold, I have lower temps after 2 hours of running tractor. (lower side of 80C mark!) Thanks for the good suggestion. Yugo