testing temp gauge

[Jerry/MT]

This thead has really gotten long for a simple problem like this. I haven't been following every detail so forgive me if I've missed something, but it seems to me you can get all the diagnostic info in about a half hour and determine what the problem is.

I presume you've tested the gauge by grounding the wire and you know that it's OK.

That leaves the sensor and the thermostat as the remaining possible sources for the low temperature indication. If you start the engine without the radiator cap on it and you let it run at ~1000 rpm , the thermostat should open in a few minutes and and you'll see the coolant circulate in the radiator. (Alternately, you can work the tractor without the rad cap installed, checking every few minutes to see if the coolant is circulationg.) If you see coolant circulate right away with a cold engine, you've verified thermostat is stuck open.
There is a posssibility that the thermostat is opening too soon. When the coolant starts to circulate in the radiator, measure the temperature of the incoming coolant. If it's less than ~160°F, the thermostat is opening too soon. This is a realtively common occurance. You can pull it and check it in a pan of hot water to verify the funtionallity.

If the thermostat opens like it is supposed to, then the only thing left to cause a low indication is the sending unit.

 

[JC-jetro]

This thead has really gotten long for a simple problem like this. I haven't been following every detail so forgive me if I've missed something

OP does not have simple diagnostic tools that most of us have. It appears that it was also an opportunity for him to get to know a bit more of general knowledge and he is appreciative of receiving it. it appears he is short handed and lives on the fringes with less stuff available to him. All we're trying to do is to help a guy with what he's got available to him. All stuff you brought up was mentioned at some point by someone.

It's all good.

JC,

 

[Caliche]

OK, can someone tell us the time difference between cold engine and operating temperature ? With a properly working thermostat? Without a thermostat for test purposes?

 

[jinman]

OK, can someone tell us the time difference between cold engine and operating temperature ? With a properly working thermostat? Without a thermostat for test purposes?

As with any engine, that depends on load, the engine type, and coolant quantity. If you mean at idle, then you have to consider what the ambient temperature is when you start. I would answer that question by saying 10 to 15 minutes, but I wouldn't want anyone to hold me to it. Nowhere in my Op Man'l or Repair Man'l does it state the average time to full warmup. Having said all this, if someone has done time-to-temperature testing on a particular model, they could certainly give a better answer than me.

 

[Caliche]

Seems to me then that after 10 to 15 min it doesn't matter whether the thermostat is in or not.
Twoone makes it sound like the thermostat cools the engine. I need one of those.
If Twoone is in a colder climate than us, then warm the engine a little then take out the thermostat, if it over heats it sure is not the thermostat doing it.
Like Jerry and JC, I must be missing something somewhere.

 

[JC-jetro]

Seems to me then that after 10 to 15 min it doesn't matter whether the thermostat is in or not.
Twoone makes it sound like the thermostat cools the engine. I need one of those.
If Twoone is in a colder climate than us, then warm the engine a little then take out the thermostat, if it over heats it sure is not the thermostat doing it.
Like Jerry and JC, I must be missing something somewhere.

T-stat acts more like an automatic flow control valve to maintain constant temp. Same as it is used in HVAC applications with the exception sending device actually sends signal to modulate a two or three way valve with pneumatic or electric operator. In automotive side, the thermostat does the same without much automation. As we drive around, the kind of work we do with the tractor, ambient temp, prevailing wind, dirtiness of the radiator core , front screen being plugged up or not the t-stat keeps and maintain a constant operating temp best for the engine and combustion ..that's the key. I know in Africa and part of middle east more on desert area it is a common practice to take the t-stat out because of steadiness of the heat in environment where even at full flow of t-stat open still engines are run hot.

Jc,

 

[jinman]

Seems to me then that after 10 to 15 min it doesn't matter whether the thermostat is in or not.
Twoone makes it sound like the thermostat cools the engine. I need one of those.
If Twoone is in a colder climate than us, then warm the engine a little then take out the thermostat, if it over heats it sure is not the thermostat doing it.
Like Jerry and JC, I must be missing something somewhere.

Wow! Paul clearly understands that an open thermostat allows water to flow through the radiator and keeps the engine from heating up to operating temperature. The engine starts cool and stays cool. That's not correct engine operation. The engine is supposed to come to operating temperature and then the thermostat starts to crack open and allow cooling water to circulate such that a stable operating temperature is reached around 185 degrees. With all due respect, you seem to be the one who does not understand the operation of the engine cooling system. If you remove a thermostat, not only will the engine not warm up to operating temperature in 10 - 15 minutes, it won't warm up in 10 to 15 hours. The tiny bit that an engine warms up without a thermostat is not sufficient in hot climates and especially in cold climates. If you live somewhere where the ambient temperature is 150-160, then you probably don't need a thermostat.

 

[Jerry/MT]

OK, can someone tell us the time difference between cold engine and operating temperature ? With a properly working thermostat? Without a thermostat for test purposes?

By cold engine I mean the engine is at or near the local ambient temperature. As an example, if you used the tractor yesterday and shut it down at sundown then woke up the next morning and before you started it, you measured the coolant temperature, you would find it was very near the local ambient temperature (It might not be exactly at the local ambient because the tractor temperature lags the air temperature in time.)

The operating temperature for a given engine depends on the ambient temperature, the thermostat rating, and the engine load. An engine is said to be at operating temperature when the coolant temperature is at a steady state value at or above the opening temperature of the thermostat. Its' not necessarily a fixed temperature. Suppose you were dragging a harrow in the spring with a 60°F ambient; your coolant temprature might be 185°F. Suppose you were baling large round bales at 90°F; your coolant temperature might be 210°F.

The important point relative to this discussion is that the thermostat should be closed on a cold engine and be open when the engine "warms up". A malfunctioning thermostat could fail in at least two ways. It can stick open in which case for the engine never warms up (except maybe for high loads and high ambient temps) because the coolant flow rate is a maximum. It can fail to open in which case the engine overheats because the engine coolant flow rate is too low. There are probably some in between failure modes where it begins to open and then gets stuck at some point.

As far as the time difference to warm up, that again depends on the ambient temperature, the coolant quanitity, the engine load, the thermal mass of the engine, radiator effectiveness, on an on, ad nasueum. As a "rule of thumb" an engine with a properly functioning cooling system will be at operating temperture in ~10 to 15 minutes of operation under normal ambient conditions (~40°F to 80 °F ambients).
If you really want to know the specific time for your engine, get a thermometer and record the time to temperture of the coolant when the thermostat opens and the coolant temperature doesn't vary anymore for various ambient temperature days with the engine idling or at say 1000 rpm.

Does that answer your question?

P.S. I would never advocate for removing a thermostat as a general rule. The engine is designd to run correctly within a controlled range of coolant tempeatures. If you had a stuck closed thermostat and absolutely had to work the treactor, then you should temprarily remove the defective thermostat and replace it with the specified unit ASAP.

 

[Keoke]

Jinman is right on the stat keeping the engine temp in the 160-180 range as being important. If engine is not allowed to warm up water condensation will form in crankcase leading to engine sludge build up; especially true under the rocker cover.
In engines that run from light loads to very heavy loads cooling system are sized to take care of heavy load cooling. Accordingly, when run at light loads the cooling system is way over-sized thus making them hard to warm up. This is why heavy trucks often use shutters over their radiators.
Also, the stat, when wide open, is a tuned orifice designed to regulate the gpm water flow through the system. Cooling liquid must spend enough time in radiator to remove heat.

On checking a one wire temp sensor, after grounding sender lead with jumper, when turning key on watch that needle climbs BUT DON'T WAIT until it hits the end of scale. This gauge is a bi-metallic hinge and getting it too hot (high current flow) could make the needle climb all the way to it's oblivion.

cheers,

 

[twoone]

Ok" Here we go again .Jim/JC and the guy's. I went and invested in a temp sensor and a new meter wit the ambient temp at aprox. 80 first cleaned all elect contact point's( note ambient temp climbing ) removed wire to sensor read 464 ohm's raid temp 80.4 time 10.44 removed cap fired eng. temp sensor raid temp time
98 10.46
100.7 10.48
105 10.48
109 10.49
168 10.54
164 114 11.02
120 11.15
At this time i hooked up the sensor ck'ed the gauge and I saw a slight raise on the gauge during the time I was checking the temp and sensor I did not see an surge in the raid.just a slight increase in rise in the neck replaced cap and turned off eng . JIM i do not think there is any problem it just runs cold as the t-stat is set at 88 degrees unless the sensor is not sending reading correct and I do not know what the correct ohms should be was going with what you and JC told me. let me know what you think.
Thank's Paul

 

[twoone]

above numbers s/b 168 ohms @ 10.54 am
and 164 ohms @11-02am
I quit at 11.15 with an eng. temp of 120 degrees
rest is temp and time

 

[jinman]

above numbers s/b 168 ohms @ 10.54 am
and 164 ohms @11-02am
I quit at 11.15 with an eng. temp of 120 degrees
rest is temp and time

Okay Paul, I was really having trouble understanding your numbers in the previous post. If I understand correctly now, your radiator never got above 120 degrees and the lowest ohms read was 164 ohms just before you quit. That tells me the sensor is responding in the general area of correct (these things are not perfect and certainly not linear). However, I don't know if it was a typo, but you said your thermostat was set for 88 degrees. If it is 88 degrees, that is Celsius instead of Fahrenheit. 88 C is equal to 190 F. That is exactly the temperature I'd expect, but your readings of temperature in the radiator only produced 120 F. That is why I still suspect the thermostat is malfunctioning. What do you think?

 

[JC-jetro]

Ok" Here we go again .Jim/JC and the guy's. I went and invested in a temp sensor and a new meter wit the ambient temp at aprox. 80 first cleaned all elect contact point's( note ambient temp climbing ) removed wire to sensor read 464 ohm's raid temp 80.4 time 10.44 removed cap fired eng. temp sensor raid temp time
98 10.46
100.7 10.48
105 10.48
109 10.49
168 10.54
164 114 11.02
120 11.15
At this time i hooked up the sensor ck'ed the gauge and I saw a slight raise on the gauge during the time I was checking the temp and sensor I did not see an surge in the raid.just a slight increase in rise in the neck replaced cap and turned off eng . JIM i do not think there is any problem it just runs cold as the t-stat is set at 88 degrees unless the sensor is not sending reading correct and I do not know what the correct ohms should be was going with what you and JC told me. let me know what you think.
Thank's Paul

Good morning paul,

had a bit of problem reading your numbers till I understood second # was actual time. If I understand it right you ran your engine sum total of 1/2 hr for your test. It appears to me even at idle you should achive around 180 degrees Fahrenheit. The conversion factor from going Cecilius to Fahrenheit is like below.

F= (C x 9/5)=32 or simpler F= 1.8 C +32


So let's plug some numbers in

initial reading:

F= (1.8x98)+32= 208 Fahrenheit which does not sound right at all as your started with cold engine.

Final number:

F= (1.8x 120)+32= 248 Fahrenheit which again does not make sense as you would have had an overheated engine.. most likely dead.

So I think you had the setting right on your gauge and the numbers you read in Fahrenheit is just fine.

You said you also bought new meter. Did you take resistance reading with your meter from cold all the way to the end of your test.? that might give us some clue. from what you reported so far I agree with Jim that it appears your sending unit is working half way decent and your problem lies with your Thermostat. You told us you already bought the t-stat. Did you not get a chance to put it in? Why don't you try to replace the thermostat to see how things go. I'm fairly confident a new t-stat will fix your problem.

Report back and we'll try to help.

JC

 

[twoone]

Good morning: I Checked the call out for the t-stat and you were correct as always, it is in Celsius not Fahrenheit I did not read it correctly in my hurry so we are dealing with a 190 degree Fahrenheit t-stat. As for the the time of day it is correct the starting ambient starting temp was aprox.80 degrees F. (and climbing) starting with a cold eng. I started test, the temp sensor was disconnected and reading from sensor to ground and the meter showed 464 ohm's,-the temp at the raid,read 80.4 degrees Fahrenheit on the gun.What I was trying to show you was the rate of temp climb.in 7 min. the eng.temp climbed to 112 degree's f. with a sensor reading drop to 168 ohm's. At 11:15 it was aprox. a 1/2 hour run and the eng, temp was 120 f degrees and the temp.sensor read 164 ohms. this was done at idle and the raid. cap off and no sign of action within the raid. except for the slight rise of fluid in the neck. I hooked up the sensor and noticed a slight rise in the gauge ,the needle was off the cold peg and about a 3ed toward the normal marker. I have not purchased the t- stat seems the dealers I checked with did not have one in stock. ? what about sensor Resistance you said about 700 ohms . Paul

 

[JC-jetro]

Good morning: I Checked the call out for the t-stat and you were correct as always, it is in Celsius not Fahrenheit I did not read it correctly in my hurry so we are dealing with a 190 degree Fahrenheit t-stat. As for the the time of day it is correct the starting ambient starting temp was aprox.80 degrees F. (and climbing) starting with a cold eng. I started test, the temp sensor was disconnected and reading from sensor to ground and the meter showed 464 ohm's,-the temp at the raid,read 80.4 degrees Fahrenheit on the gun.What I was trying to show you was the rate of temp climb.in 7 min. the eng.temp climbed to 112 degree's f. with a sensor reading drop to 168 ohm's. At 11:15 it was aprox. a 1/2 hour run and the eng, temp was 120 f degrees and the temp.sensor read 164 ohms. this was done at idle and the raid. cap off and no sign of action within the raid. except for the slight rise of fluid in the neck. I hooked up the sensor and noticed a slight rise in the gauge ,the needle was off the cold peg and about a 3ed toward the normal marker. I have not purchased the t- stat seems the dealers I checked with did not have one in stock. ? what about sensor Resistance you said about 700 ohms . Paul

Paul,

It is very plausible that your sender probably is okay. You might have a bit of error in reading due to the meter but they can calibrate the gauge between 460 to say 80 ohms to show full range of temp. The sender and the gauge are a matching unit. I have not done this myself but there is nothing magical about a thermostat. I bit ya if you take the t-sat off and take it to NAPA auto store they might be able to match up one for 190 less then $15.

Again you might be able to nip off the "thingamagic" that opens the bypass hole. That might have kept the thermostat opened. Then you just need to cut it off and put the old -t-stat back again.

Now one thing you have not done is to take a t-stat housing temp reading at the end of you 1/2 hr test. I wondered what the difference would be between that and the radiator temp of 120.

JC,

 

[jinman]

I agree completely with JC. Pull that thermostat and look at it. You may be able to cut off the "dangle" and get it working. If not, take it to NAPA and save yourself some money. I betcha they have an exact replacement that may work better than the original for about 1/2 the cost or less.

I really think you are on the "home stretch" and leading the race. You're almost to the big payoff.:thumbsup:

 

[twoone]

Hi"
As a mater of fact I did read the T-stat housing just to see if there was a overheat while at 120f degrees but I did not write it down and I can't remember what it was however I recall it being some where close to the same temp. there was only a slight difference higher and remember the ga. did move. I hate to do the same job twice by opening the T-Stat housing with out parts the idea about Napa sounds like a good one, I guess the difference between $10.00+ and $52.00 +that the dealer wants is worth it. I checked the price at Messicks and they want $36.00+but neither had one in stock and i would still will need the proper gasket. I am thinking of waiting till i work the tractor and check it as opposed to now at only a idle check. Am not using it much now as were out of season but some jobs and work do come up? what about the seeing the water move , Even at idle shouldn't I see it moving if the T-stat is stuck open ? and if it were stuck closed shouldn't the temp rise to more than 120f degrees in a half hour at idle/1500 rpm.? this all blows my mind that's why I am thinking that the later test might be a good idea and to compare. . What about the temp sensor ohm reading at hot and cold is there a standard for this ga.2: Paul

 

[jinman]

I think watching for water moving is very subjective. It's very hard to see water move unless you are watching something floating as it moves by.

On the thermostat. . . Your gasket is probably going to be easy to match at NAPA. Remove the neck that goes into the hose and take it with you for a perfect match. If they don't have one, they are easy to make from some gasket material. Just put the material over the opening and tap lightly with a hammer to make an impression. Then, use a cutter to cut out the center and a pair of scissors to trim the outside. You can carefully drill holes in the material with a sharp drill. I don't think you will have to do that because NAPA will surely have a size to match. Of course, it's your call. Once you've done it, it seems easy, but I can understand your point since you've never replaced a thermostat. Honestly, I've removed lots of thermostat necks and just used blue gasket making silicone to patch up any breaks in the gasket. It's your tractor and your job, so do what you are comfortable doing.

 

[JC-jetro]

Paul,

ditto On what jim said about blue RTV gasket. Once I actually managed to damage a brand new gasket that I bought putting a water pump in. I was supposed to use if I can remember "Indian Head" red color high temp sealant. I had to get the vehicle moving and had no choice and no access to store. I actually used cereal box cardboard and made as close replica of the old gasket as I could using punch, razor blade and scissors. I then smeared blue RTV on both side and let it skin a bit, put a little extra on water pump housing to keep the gasket in place while putting in the water pump. My idea was this is just temporary till I get a new gasket. It never ever leaked a drop and I finally sold that old car with my temporary fix.

JC,

 

[barbqranch]

If you make a gasket, there is a better way to make the bolt holes. If you have a large ball bearing, put it over the gasket on the housing and tap with a hammer. It will act as a hole punch and make a perfect hole.