2001 ranger temp gauge below normal ??

[jarfly]

can someone help me here ?
my 2001 ranger xlt 4.0 always ran with temp gauge in the middle.
Just lately it will only go about 1/4 up.

I have checked coolant level = ok
Heater is really great.
i have removed the left sensor(type with o-ring,instead of threads) and heated the brass end with my bic lighter and gauge pegged out, so i dont think its this sensor.

OK, the other sensor to the right of the other one(i think it goes to the computer) i havent removed. Looks like the top intake must be removed to get to it.
Could this one be the culprit ?
someone help me here. thanks

 

[pcollins]

Instead of heating it with a lighter next time just stick it on metal and it'll tell you if its working. They work on resistance. honestly that gauge is pretty inaccurate and is probably as fake as the oil pressure gauge on these trucks. Get an Infrared thermometer and measure Your coolant temp in a few places.

 

[cowboykilroy]

My first thought is the thermostat is not closing to allow the engine to build temp.When the engine is cold take the radiator cap off and start the engine if you can see coolant flow the t-stat needs to be replaced.

 

[jarfly]

coolant doesnt move with radaitor cap off cold.
heater is good and hot. i can drive it an hour or more and gauge barely goes up. used to run in the middle.

ive narrowed it down to the temp sensor(the one to the right of the other one)the one that goes to the cpu.
Will this one cause the gauge to read low ?

and the upper intake must be removed to just get the wire off(pita)

so how big a job to remove the upper intake ??

ive done a lot of mechanic work on the older models so im no newbie but on the newer models i am.
thanks all.

 

[jarfly]

are both sensors the same ? seems parts stores cant tell me nothing.

 

[Earl43P]

One coolant temp sender drives the gage, the other only feeds the PCM (and cannot affect the running temperature). Step one should be to replace the thermostat.

It is also possible that your fan clutch is engaged, making the fan overcool the radiator.

The Coolant Temp sender for the PCM is NOT your problem.

 

[jarfly]

Thanks Earl.
thermostat replaced. same low gauge reading.
i also chked old thermostat in boiling water and it opened and closed good.
heater good and toasty.
its not the gauge either as i can heat the brass end of the left sensor with my bic and gauge pegs out.

its about a 1 hr drive to the nearest parts store and gauge moves about 1/4 up.
maybe left sensor is weak ??? or does it work or not work ?
ok not chked fan to see if its staying engaged.
sitting idling same low reading also.

cant afford many trips to parts store, someone help me guys, this is my wifes vehicle, if i drove it id pay no attention unless it overheated.
thank you, Dave

 

[exbass94]

You've established that the sensor for the gauge (and the gauge itself) works correctly. So when it tells you the engine is not getting hot enough, the engine is not getting hot enough! Sounds like a cooling system problem, not a sensor problem. The other sensor does not control engine temperature, it only tells the computer what the temp is so the computer can adjust other parameters like air/fuel mixture.

Just because the heater works fine doesn't mean the engine is up to full operating temp. My heater starts to work when the gauge has barely moved off "C."

Since you already replaced the thermostat, the fan clutch would be my next suspect.

 

[bilzy7]

I have same exact issue. I hear fan like noise from front right from start up, kind of a whistling. I always thought I just needed to replace some pulleys... But reading this makes me think fan clutch... My heat has gone some but still works good.