2000 Jeep XJ 4.0l
Mia it possible to repair the temp gauge on the instrument cluster?

 

It should. Verifiy first if it's your gauge, sensor, or even both. If you need help let us know.

 

I replace the sensor and have not put it through the test yet, what has been going on is that once it breaches 225 degrees it will continue to move over to 260 degrees, not slowly but immediate

 

So are you overheating?

A rapid rise once the cooling system fails and the thermostat has tried to open as much as it could, is not uncommon- its the system decompensating and your coolant then moving towards boiling.

I would verify the temp first, with an infrared thermometer/gun. If you have a simple scantool that also has Live Data (buy one, it will come in handy in the future too, no doubt) you can verify if it is actually reading correctly and that your sensor is working. We can then go from there.

 

Had a Radiator shop for years in Nevada. from early on I always been curious about How thermostat does it.
from Stant engineering. It takes 24 degrees to open a thermostat to full open. So, a 180-degree thermostat will be fully open at 204 degrees (use a temperature gun to prove it). notice 204 is NOT boiling (212). So, a 195 will be fully open at 219. of course, you won't read 219 on your hand gauge unless it pressurized.
3 degrees per pound of pressure is the standard for pressure caps if you choose to adjust. 10 lb. cap increases boiling point of radiator mix to 242 (from 212 +30).
all of this can be read with your hand-held temp probe. finishing up with a 16 lb. cap at 3 deg. per lb. = 48 + 212 = 260 before boiling occurs.
On my 1993 4.0 the gauge sender (not the sensor) at the rear of the head will turn on the cooling fan when excessive temp occurs. there is a number (?) that the gauge sender Ohmic valve will turn on the cooling fan 370- 410 ohms or lower toward zero ohms ...

 

The issue I’m having with my temperature gauge is that once the temperature goes over the second tick passed 210. It immediately just rolls to overheating rather than gradually going over there.

 

what is the best temperature switch/sensor to use?

 

Most infrared tools should work. ( to read temp at sensor location ) , I painted the area black to get a good reading. ( example paint the thermostat cover ) you'll read very close to actual temp.
when your system is pressurized "BOILING" is heald back.... Temp still can rise, as long as pressure holds, but the
instant pressure is released ,( its already beyond boiling .... THATS STEAM ) so
be very careful if this is your issue. A system that is UN-pressurised ( bad Cap) will not go above 212 ,boiling.
Perhaps the gauge is at fault.

 

Sounds like it's not holding pressure. Check your cap. You can rent a pressure tester for "free" at a local autoparts store to test the cooling system. Another possibility is your thermostat is not opening properly.

As others have said, check the temp using live data on a scan tool or infrared thermometer. Make sure your overflow tank is full. Look for any bubbles in it once it starts to overheat.

 

In the absence of a Snap-on scan tool( 6K$ ) ,,, another gauge wired in (lose) either mechanical or electric and then you can actually watch and compare your temporary to the dash as it happens. Just remember these parts are made by humans and not always 100% perfect , or perfectly tested, Sooooo the internal workings ( resistances and Ohmic values ) of the sensor and wire and gauge all have to add up correctly ( perhaps the PCM also)