Thermostat Question

Just installed my [b:0b1cac4923]4th.[/b:0b1cac4923] thermostat in my 640. All have been 160 deg., all from different vendors (I think), last being from this site.
All have done the exact same thing, they open at 190 deg. then the temp drops off bottom of the gauge then starts to creep up.
Thing is the temp [b:0b1cac4923]never[/b:0b1cac4923] reaches 160 deg. again. Even in the Texas summer heat bush hogging it barely reaches 160 deg.
The newest one I put in a couple of weeks ago does the same thing, but it opens at 185 deg. both in a water test (with digital thermometer) and in the tractor. Yesterday it was about 43 deg. out, I was pulling a 7ft. box blade filled to the top with caliche up a grade of 10-15 deg. and temp. only got to 140 deg, then went back to 140 deg. on level ground.
Over the years everything I've owned with a thermostat has gotten to the temp and stayed there which tells me it was cycling. Not with this. Also this new thermostat has a weep hole with a little plastic piece that helps prevent and air pocket.
 
I have read there are two types of thermostats.. cheap ones that are fully open or fully closed...

more expensive ones that actually vary open and closed to give perfect temp control...

some manufacturers make both types.

Lots of articles on the internet complaining about thermostat bounce or temp bounce.. In your case its not getting above 160, so no worries about the engine other than its running a bit cold... The full flow type of thermostats can be worse.. the ones with the jiggle pin or 3/16s pin hole seem to be better at avoiding bounce and also bleeding air out of the system. They also can keep the engine from forming steam pockets on "quick hard load" warmups. A bad temp gauge can also show a lot more bounce is if it's off on the lower end. Modern cars have even dummyed up the temp gauge to hide the bounce.

The three legged thermostats are usually the high flow and will bounce more. sometimes better and more expensive, is not better. Especially if your engine is running cooler and the thermotats is fully opened, then you will see temp drops alot... a smaller cooling system or flow will keep it more consistent. But tractors by nature are made to work hard and have over sized systems... so bounce is actually a product of the design with light loads.
 
Unless you are really unlucky with new parts, you have something else going on, such as a failed head gasket that is allowing combustion products to get into the cooling system.
 
Yea, 160 is too low. Go with a 180 or so thermostat. Also, drill a 1/8" hole in it to allow trapped air to escape if it already does not have one. Double check to make sure the thermostat is not installed backwards. Usually, spring end goes toward the engine.
 
As stated, this last one came from this site and was probably the most expensive one I've bought so far.
Also this is the second temp gauge, and both did the same thing.
As far as the combustion, don't see any problem there, no bubbling etc.
Also installed correctly.
Replaced the radiator several years ago, acted the same way as the new one.
 

I have a couple of questions.

Why do some people say that 160 is too low? :? My 860 came from the factory with a 160 degree thermostat. And that is what it has in it now. It has ran for 57 years with a 160 degree thermostat.

Is your temperature gauge's sending unit mounted in the factory location? I have seen people install them in locations that defy logic. Different locations can result in vastly different indicated temperature.
 
I changed the thermostat on neighbors McCormick, saw the same thing. I have enough to do this winter, but plan to use IR sensor on it in the spring.

I will make judgement after more diagnostics.
 
I'd install a 180 or so degree stat and see how that works... I'm wondering if this one is just maintaining about 160 deg... which is not a lot... so it stays open all of the time. The gauge is probably not all that accurate on it's lower end either... so prob a combination of the two things. Warm it up some and I think the problem will go away.

Rod
 
(quoted from post at 12:38:57 11/14/14) I'd install a 180 or so degree stat and see how that works... I'm wondering if this one is just maintaining about 160 deg... which is not a lot... so it stays open all of the time. The gauge is probably not all that accurate on it's lower end either... so prob a combination of the two things. Warm it up some and I think the problem will go away.

Rod
Again, this is the second gauge, and it's mounted where it should be and it's doing the exact same thing as before, not even maintaining 160deg.
Only way to raise temp in the winter is to put a piece of cardboard in front of the radiator, even then it just barely hits 160.
160 is what's supposed to be in it, but some have said with the new crappy fuel it should be higher.

With all the posting over the years about overheating I'll bet some wish they had this problem. :lol:
 
Take something and poke in the hole where the sensor bulb goes could be a lot of sludge buildup that keeps the water away from the bulb.
 
You can obviously do as you like... but 160 deg is barely hot. Anything today is going to run 190 plus... and it really has no bering on it's ability stay cool.
I think you have a thermostat doing exactly what it's supposed to do at 160 deg... which is stay bloody wide open. Any gauge you buy today is probably so poor it can't accurately register 160 deg to begin with... so there's probably nothing wrong. You just think there's something wrong.
If you're going to run it in cold weather I'd install a 'winter' thermostat... which will be about 180 deg.
I'm not rightly sure what was recommended on that particular tractor but the generations that followed could be equipped with anything from a 160 to 188 deg stat.. depending on how hot someone wanted them to run. I never use anything less than a 188 because Basildon engines run like sick dogs when they're cold. They have to be hot.
Yours... probably not so much... but I'd still warm it up some.

Rod
 
As I read this, I'm getting the feeling that you don't know for sure if thermostat(s) are functioning. Try placing one or more in a pan of water on the stove and bring to a boil. Have wife's cooking thermometer handy and see what temp. is when the units pop open. Right now, you are "guessing" that the stats are working properly for their temp range.
 
One of my NAA's is like that. Doesn't concern me, just a good shape cooling system. No matter how hard I work it, it'll just make the thermostat temp (maybe)...that's it.
Hard to believe, but tractor cooling systems are so robust, just the flow thru the thermostat bypass hole is sometimes enough when not working hard.
I just change the engine oil in that one more often.

First, after running it a while, what does your meat thermometer in the radiator neck say? This is the only reading to be trusted.

How many blades does your fan have? I had a 850 with a 6-blade
fan and it would super cool...and sounded like a howling banshee.
I put a 2-blader on it that I had laying around.

If it really bothers you, make your own thermostat.
Round disk, with a hole in it. Experiment with the hole size.
It'll warm up slower, but I think you said Texas, so no matter.
That'll even out the gauge swings.

And while I absolutely wouldn't do it to one of my tractors....
if you have a real cold runner, take the radiator shroud off.
It'll run warmer then.......
 
(quoted from post at 23:23:05 11/14/14) As I read this, I'm getting the feeling that you don't know for sure if thermostat(s) are functioning. Try placing one or more in a pan of water on the stove and bring to a boil. Have wife's cooking thermometer handy and see what temp. is when the units pop open. Right now, you are "guessing" that the stats are working properly for their temp range.

I did that before I installed it using a digital probed thermometer.
One thing I haven't done is to check the water temp to see if it matches the gauge.
It's a 3 blade fan.
Meanwhile I'm trying to locate a 180deg. but no luck so far. All I've found is either 160 or 188.
 
(quoted from post at 08:34:30 11/15/14)
(quoted from post at 23:23:05 11/14/14) As I read this, I'm getting the feeling that you don't know for sure if thermostat(s) are functioning. Try placing one or more in a pan of water on the stove and bring to a boil. Have wife's cooking thermometer handy and see what temp. is when the units pop open. Right now, you are "guessing" that the stats are working properly for their temp range.

I did that before I installed it using a digital probed thermometer.
One thing I haven't done is to check the water temp to see if it matches the gauge.
It's a 3 blade fan.
Meanwhile I'm trying to locate a 180deg. but no luck so far. All I've found is either 160 or 188.
sure wouldn't sweat the 8 deg delta (188-180). When heating in pan of water, did you observe the stat slowly opening as water warmed & slowly close as water cooled? That out to lay aside the "snap open/snap closed" ideas. I have boiled any number of thermostats & never seen a snapper!
 
(quoted from post at 12:25:48 11/15/14)
(quoted from post at 08:34:30 11/15/14)
(quoted from post at 23:23:05 11/14/14) As I read this, I'm getting the feeling that you don't know for sure if thermostat(s) are functioning. Try placing one or more in a pan of water on the stove and bring to a boil. Have wife's cooking thermometer handy and see what temp. is when the units pop open. Right now, you are "guessing" that the stats are working properly for their temp range.

I did that before I installed it using a digital probed thermometer.
One thing I haven't done is to check the water temp to see if it matches the gauge.
It's a 3 blade fan.
Meanwhile I'm trying to locate a 180deg. but no luck so far. All I've found is either 160 or 188.
sure wouldn't sweat the 8 deg delta (188-180). When heating in pan of water, did you observe the stat slowly opening as water warmed & slowly close as water cooled? That out to lay aside the "snap open/snap closed" ideas. I have boiled any number of thermostats & never seen a snapper!
I didn't let the water cool, just pulled it out and watched it close.
Got a 180 on the way.
 
It sounds like maybe your gauge is not reliable, but also, If I were you, I wouldn't run a 160 degree stat in it. I'd stick with a 180. I ran a 160 in my corvette part of the time because the cooling system is limited and I had some stuff highly modified. On most engines, you want to maintain enough head to dry out the crankcase and promote good fuel vaporization and combustion. Running an engine too cool promotes sludge buildup.
 

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