Ford 1920 thermostat temp

[Jerry/MT]

Hello I have a question regarding the different temps for the thermostats. I have a 1989 1920. I just noticed that my temp gauge doesn't seem to move at all. I have been running the tractor relatively hard but the air temp is quite low 10s-20s. I don't know if my gauge has a shorted wire and isn't receiving temp infor from the sensor or my tractor just isn't getting up to temp. The radiator seems warm but not hot when the tractor has run for awhile but gauge never registers. Is this a thermostat issue or is it most likely a bad wire from the sensor to the gauge? If I have a 160 deb thermostat could this be causing the problem? Thanks. I am always amazed at the wealth of knowledge here!

It could be a thermostat that's sticking open and not allowing the engine to come to temperature. Pull the thermostat and check it out. It's not good to run any engine without a functional thermostat.

 

[pedalstomper78]

It could be a thermostat that's sticking open and not allowing the engine to come to temperature. Pull the thermostat and check it out. It's not good to run any engine without a functional thermostat.

100% correct. Engine are built to tolerances. Things expand as they get warm. That's why we use a thermostat to regulate that expansion. Running it cold leads to looser tolerances and more wear to put it simply.
For as cheap as a thermostat it, just replace it and eliminate it as a problem. It's a cheap replacement part and gives you an excuse to change out the coolant at the same time to keep everything else in good condition.

 

[JC-jetro]

Your sending unit is a variable Resistance type temperature sensor. Cold resistance about 700 ohms, (might vary some from makes or model) , operating about 140 ohms, 80 to 100 ohms. Again these are the number for my Ford 1700 and there is some variability. If when you put the key in ignition and turn (not crank ) and the temp needle pegs then as soon as engine cranked and running it goes to zero and starts to creep up as the engine get warmer. Do a test by putting the key in to see if the needle pegs, while the key on then remove the lead from the sending device and your meter should peg. That test shows if wiring is intact. next is to verify resistance at cold and then operating temp. report back to compare and contrast.

JC,

Hello I have a question regarding the different temps for the thermostats. I have a 1989 1920. I just noticed that my temp gauge doesn't seem to move at all. I have been running the tractor relatively hard but the air temp is quite low 10s-20s. I don't know if my gauge has a shorted wire and isn't receiving temp infor from the sensor or my tractor just isn't getting up to temp. The radiator seems warm but not hot when the tractor has run for awhile but gauge never registers. Is this a thermostat issue or is it most likely a bad wire from the sensor to the gauge? If I have a 160 deb thermostat could this be causing the problem? Thanks. I am always amazed at the wealth of knowledge here!

 

[ErikVann]

Ok so I did the test as described by JC. When I turn the key but not crank the temp gauge stays put. Fuel gauge climbs but temp is stationary. If I disconnect the lead to the thermo and ground it the gauge climbs. So am I correct to assume that there is not a bad wire between the thermo and the gauge. So is the next step to pull the thermostat? When I do this should I drain all the antifreeze first? Sorry for the newbie question I am a new comer to most things mechanical. Which thermostat should i plan to install if that is the case? should i plan to change the thermostat seasonally as was alluded to by someone earlier in the thread? I also noticed that the radiator cap seems to have had some overflow. I am not positive about this because I did remove the cap recently while it was warm.

 

[JC-jetro]

Ok so I did the test as described by JC. When I turn the key but not crank the temp gauge stays put. Fuel gauge climbs but temp is stationary. If I disconnect the lead to the thermo and ground it the gauge climbs. So am I correct to assume that there is not a bad wire between the thermo and the gauge. So is the next step to pull the thermostat? When I do this should I drain all the antifreeze first? Sorry for the newbie question I am a new comer to most things mechanical. Which thermostat should i plan to install if that is the case? should i plan to change the thermostat seasonally as was alluded to by someone earlier in the thread? I also noticed that the radiator cap seems to have had some overflow. I am not positive about this because I did remove the cap recently while it was warm.

Eric,

On my 1700 when I out the key in "on" position not crank, it pegs and let me know the circuit in in place. On some I know it does not peg on "on" position but creeps up as the engine heats up. Grounding it and it and the needle pegging is indication of " good wring". Before I go to t-stat check, I would try to read cold and hot ohms out on the sending device. That costs no money and no effort. if don't see variance in resistance then the sensor is bad. I'd replace the sensor and test it out, if all's well then i leave it be. If no change then I go to T-stat checking. You need to drain a cold engine enough to lower the water level below the t-stat to take out and change. I'd save that coolant if it looks good in a clean bucket, use coffee filter to filter and put it back in. You can test the t-stat in ice water and then in boiling water to see if it actually opens and closes. If I go to the effort of taking it our I'd just put a new one in. Let's do what is non-destructive first before you go to a more detailed work. Cap has a spring that opens up at 7 or 15 psi. your cap might be not sealing tight or it's stuck open.

JC,

 

[ErikVann]

When I remove the wire from the sensor is that the thermostat or is that in another location? How do I go about reading cold and hot ohms? Is that engine temp? And where should I be testing for the ohms? I assume at the sensor and the gauge. Does that require dismantling the dash?

 

[JC-jetro]

When I remove the wire from the sensor is that the thermostat or is that in another location? How do I go about reading cold and hot ohms? Is that engine temp? And where should I be testing for the ohms? I assume at the sensor and the gauge. Does that require dismantling the dash?

Erik,

Have you ever used an Ohm meter? Not a big deal if you have not. OHM meter has a battery that provide a bit of current in to a circuit and measures in Ohm the resistance whole or part of a circuit. The body of the sending device is grounded or negative. Use on wire from the ohm meter and with an alligator clip to the electrical connection (same place where you took the sending wire off and grounded it) , the other wire need to be connected to a good ground, not on paint, and then read the ohm. ohm meter can also be a voltmeter as well. make sure it is set to ohms, and the range is where you can read under 1000 ohm for a better reading, don't use K-ohm(ohmsx1000). do this with engine cold and record. Turn the engine on and let it get good and hot, turn the engine off and read the ohm again making sure not to burn yourself, record ohm. come back with your result to see if that sheds any light toward proper diagnosis.

JC,

 

[90cummins]

Can't tell you what is recommended but I will say I installed a 190 deg in my Ford 1720.
I refused to get the business from Ford NH so I purchased it from Advance Auto after I went thru their entire bin to match the style & size.
My T stat was oval/off center so I modified a premium symmetrical Stant to match the original and have had no issues.
I opted for the 190deg because I want the engine to warm up thourghly and stay warm while it is performing low power tasks, diesels love HEAT!
90cummins