2020 4815C(H) Engine temp dash monitor

Texasmark · Mar 3, 2022

ptsg said:
If anything, a red light will bring more attention than a temp gauge that will barely move when it's getting hot. And yes, I do monitor all my gauges constantly as well.

I still struggle to understand why this is such a big deal that would stop someone from buying said tractor. Would I prefer an actual temp gauge? Absolutely, specially being a digital dash, they could actually show the exact numbers instead of a gauge, but wouldn't change my buying decision based on the lack of a temp gauge.

Took a screenshot out of the service manual for the 2020+ 15 Series. It has the new style dash that K5lwq showed on the previous page. As you can see on the middle position of the needle, it can either be 70ºC or 107ºC. Confirming what Eric said about being pretty much a 3 position thing.

View attachment 735531

And the old dash style for comparison, showing temp variations a lot better.

View attachment 735532

Well you have an analog instrument driven by a varying resistance as a function of temperature which is how temp monitors work. Using some common sense here..........the needle will not sit in the center mark while the resistance changes as mentioned in the chart. The center point of the resistance posted is about 190F which is where my Ford 3910's thermostat starts to open and is a good temperature for running a diesel and expecting to maximize combustion efficiency.

My bet is that the intermediate marks are at 158 F and 232F. This isn't a 3 position instrument as claimed. If it were you would have 3 separate thermal sensors and when their temperature was exceeded a switch would activate and the meter would step function to the corresponding position......fat chance on that being the case!

One should expect the needle to rise linearly till it hits the center mark and then stay there while the thermostat continues to open as the engine heats, producing very minor variations in the needle positon. When the load exceeds the cooling capacity, then the needle will start moving again at a pace similar to the initial deflection.

If the needle gets to the hot marker, you had better cease operation because at 248F you are exceeding the ability of your 50-50 antifreeze and radiator pressure cap to retain the coolant in the radiator....
ALA boil over time!

K5lwq · Mar 3, 2022

Texasmark said:
Well sir, since you own one, how do you monitor your engine temperature?

I look at the gauges. Mine has the same cluster that is in the manual.

ericm979 · Mar 4, 2022

Texasmark said:
My bet is that the intermediate marks are at 158 F and 232F. This isn't a 3 position instrument as claimed. If it were you would have 3 separate thermal sensors and when their temperature was exceeded a switch would activate and the meter would step function to the corresponding position......fat chance on that being the case!

They do the three position gauge with one sensor. The gauge is controlled by a hardware or software logic circuit, it's not analog like you're thinking. I have watched gauges like this in vehicles where I also have a direct read of the temp sensor via OBD2, and yep, "low" and "normal" positions cover a wide range of sensor values. Never got to "high".

Look at the manual pages ptsg posted.. the new style three position one is "stepping motor type + ECU control". It's controlled by software.

LouNY · Mar 28, 2022

A bit late for the party but;
there is one simple way to find out if your temperature gauge is linear and accurate.
Park next to an electrical outlet, get a hotplate and a pan of Ice water extend the leads for your temperature sensor.
Measure the resistance with the sensor in Ice water and go ahead and put a thermometer in the water also,
you should be reading the resistance for 0C/32F and when hooked up your gauge should be indicating cold.
Start heating the water with the hot plate monitoring with you thermometer let the water temperature stabilize
around say 50C/122F, measure the resistance and verify your gauge reading.
Now repeat this step around 80C/176F and repeat measuring the resistance and verifying the gauge reading.
Now heat the water up to a light boil your thermometer should be reading close to 100C/212F, measure the resistance and
verify the gauge reading.
Now you will know were your gauge reads at various temperatures and especially at boiling with just atmospheric pressure,
so your tractor is still safe at 212F/100C but it's time to clean or at least check it over.