Stuck themostat: I think?

[PastureKing]

In my less than 12 posts, this is the first that I have attempted to attach a photo.

If you see the photo, it is a thermostat from my JD950, which has been overheating. I replaced the water pump and thermostat last year, but it is again overheating this year. The thermostat that I replaced last year... appeared just as this one does, with the rod extended out and to a ~120 degree angle.

It seems to be stuck, but I don't know enough to know if this is normal, if it is stuck open or stuck mostly closed.

Finally, what are the cons for running my tractor without the thermostat until a new one arrives. I need to do cut a pasture soon.

Thanks

 

[Midniteoyl]

You have the right thermostat? There appears to be some kind of damage to the stat and I can only think that its because its the wrong one.. Or installed wrong.

You can run all you want in the warm months without a thermostat.. just let it warm up a few extra minutes before running hard.

 

[TractorTech]

It is definitely stuck open. Just because it was a year ago that you replaced it doesn't mean it can't be at fault. It is either a bad design or poorly made.
The thermostat acts by trapping hot water in the radiator long enough to let it expel excessive heat. Meantime, cooler water warms up to pre-determined temperature of thermostat until hot enough to open. Without the thermostat, the water continuously heats up until the system overheats.
Go to an auto parts store and try to match up with an import model thermostat if a direct cross reference is not available. It will get you going for now.

 

[Baby Grand]

<snip>

Without the thermostat, the water continuously heats up until the system overheats.

<snip>

With a stuck closed thermostat, yes. Without the thermostat, or with a stuck open thermostat, the coolant will flow through the radiator continuously, resulting in a cooler operating temperature. Not such a problem in hot weather, but something you need to fix before it gets cool/cold, or your engine will never "warm up".

 

[PastureKing]

It is a genuine JD part from the JD retailer. It can only be installed one direction.

I'm going to see how long it runs without overheating now.

 

[sd455dan]

In my less than 12 posts, this is the first that I have attempted to attach a photo.

If you see the photo, it is a thermostat from my JD950, which has been overheating. I replaced the water pump and thermostat last year, but it is again overheating this year. The thermostat that I replaced last year... appeared just as this one does, with the rod extended out and to a ~120 degree angle.

It seems to be stuck, but I don't know enough to know if this is normal, if it is stuck open or stuck mostly closed.

Finally, what are the cons for running my tractor without the thermostat until a new one arrives. I need to do cut a pasture soon.

Thanks

That thermostat is not only (stuck WIDE OPEN) it looks to be hyper extended or damaged, throw it away and install a new one...

The spring side always goes toward the cylinder block / or head... Good luck.

 

[RobJ]

With a stuck closed thermostat, yes. Without the thermostat, or with a stuck open thermostat, the coolant will flow through the radiator continuously, resulting in a cooler operating temperature. Not such a problem in hot weather, but something you need to fix before it gets cool/cold, or your engine will never "warm up".

Actually in certain conditions yes without one could cause overheating. It helps to regulate the water flow through the radiator. It's primary purpose is to maintain a constant engine operating temp, which is better for your engine. Stuck open and you may not notice it right away, closed and you will soon.

 

[ovrszd]

That thermostat is definitely bent. I can't even figure out how it could get bent like that??? I'm curious to hear the answer for this problem.

 

[mfreund]

Actually in certain conditions yes without one could cause overheating. It helps to regulate the water flow through the radiator. It's primary purpose is to maintain a constant engine operating temp, which is better for your engine. Stuck open and you may not notice it right away, closed and you will soon.

How could no thermostat cause overheating?? No thermostat would cause engine to run cold, could not cause overheating.

 

[Clint S]

How could no thermostat cause overheating?? No thermostat would cause engine to run cold, could not cause overheating.

Like he said it helps regulate the flow of water through the radiator by causing resistance. In some instances running without a stat will cause the fluid to circulate too fast. It will not stay in the radiator long enough to cool.
T stats, like said above are to get the engine up to operating temperature and keep the engine running in a temp range. If it's too cold they close, but if it's too hot they open and stay open . If you have cooling issue not running a stat or running a cooler one will not prevent or fix the issue. It will just take longer for the overheat to happen.

 

[Midniteoyl]

The reason NOT having one could cause a slow overheat is because of pump cavitation. But, its unlikely at these low RPMs.

 

[MHarryE]

I can't say definitely for your particular system but many are made that will partially bypass the radiator f the thermostat s removed. To run our cooling tests to determine the true cooling capability we have special blocked open thermostats, use pure water for coolant, and run at laid until the temperature stabilizes. That way we can run a cooling test on an 80 degree day and extrapolate to determine how it will do on a 120 degree day. If we run with no thermostat the engine will stabilize at a higher temp because of some coolant bypassing the radiator.

 

[Baby Grand]

Mmmmmmmmmm. Crow tastes great!
I guess I learned something today.

 

[ovrszd]

Mmmmmmmmmm. Crow tastes great!
I guess I learned something today.

Heheheheh. I learned this lesson years ago when my eldest Son bought a Olds Cutlass 455V8. It was running hot and we discovered the thermostat was bad. Took it out. Car wouldn't heat up unless you headed down the highway at cruising speed for a few miles. Heat just kept building until finally it would boil over. Coolant was going thru radiator too fast.

 

[Midniteoyl]

I can't say definitely for your particular system but many are made that will partially bypass the radiator f the thermostat s removed. To run our cooling tests to determine the true cooling capability we have special blocked open thermostats, use pure water for coolant, and run at laid until the temperature stabilizes. That way we can run a cooling test on an 80 degree day and extrapolate to determine how it will do on a 120 degree day. If we run with no thermostat the engine will stabilize at a higher temp because of some coolant bypassing the radiator.

Interesting! Any reason why this is done? I know in older cars/trucks there was a bypass for the heater, but removing the stat didnt mean you would overheat... I cant see a reason for a tractor.

 

[TractorTech]

Overheating without a thermostat takes time, but once it starts getting hot, it can not cool down, unless you shut it off.
It depends on the cooling capacity as well. As some have shared, certain engines won't heat up. If you have an adequate coolant capacity, it won't heat up, but some smaller systems, such as those on the Japanese tractors, don't have much extra capacity.

 

[KYErik]

MHarry is right- It depends on the cooling system design as to whether no thermostat might lead to overheating. If the thermostat is regulating flow through heater hoses and if removing the thermostat then allows the waterpump to bypass the radiator and cycle coolant in and out of the engine, then yes it can lead to overheating (the radiator gets less coolant flow and gives up less heat).

A lot of websites state that you should not remove the thermostat because coolant can flow through the radiator too fast to give off heat- but the physics of heat conduction just doesn't work that way. If the fluid velocity is twice as fast, then yes, a water molecule travels through a radiator in half the time but there are twice as many water molecules moving through the radiator and transferring heat.

If you have plenty of airflow through a radiator (heat exchanger), a higher coolant flow rate will always transfer more heat from the fluid and into the air.

That said, there really isn't a reason to remove a thermostat and run the engine without it (unless it is stuck closed and the auto parts store is closed for the weekend). A lot of people remove the thermostat and it doesn't help their overheating problem because the radiator is plugged.

Removing a thermostat always causes its own problems (lower operating temps, lower oil life, higher cylinder/ring wear rates). None of my tractors had thermostats in them when I bought them, but I installed them so the engines would last longer.

 

[RobJ]

A lot of websites state that you should not remove the thermostat because coolant can flow through the radiator too fast to give off heat- but the physics of heat conduction just doesn't work that way. If the fluid velocity is twice as fast, then yes, a water molecule travels through a radiator in half the time but there are twice as many water molecules moving through the radiator and transferring heat.

Reminds me of the insurance commercial about the girl who learns everything on the internet. Met the French guy on the internet to.

But same principle with HVAC systems and heat transfer.

I know my feet have plenty of fluid in them. If I run barefoot across a hot parking lot my feet don't get as hot if I take a casual stroll. So heat is being transferred to my feet for sure. OK so the physics are probably not the same..wait...let me Google it.

J/K...

 

[Midniteoyl]

Haha..

 

[holt50]

holt50 I HAD A TRACTOR THAT I THOUGHT WAS RUNNING HOT AND CHANGED THE THERMOSTAT;COME TO FIND OUT IT WAS THE SENDING UNIT ,YOU CAN GET A PIECE OF 12 TWO COPPER WIRE AND OPEN THERM. AND PUT IN WIRE AND IT WILL HOLD IT OPEN, WON'T RUN HOT THEN ,IT TAKES A LITTLE LONGER TO WARM UP IN THE WINTER