New Mopar Sensor Reads Different:
Thread Starter
Senior Member


Joined: Apr 2009
Posts: 819
Likes: 7
From: VA
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
I replaced the water temp sensor with a new OE sensor by Mopar. The Mopar water temp gauge is reading 10 to 15 degrees hotter than my previous one.
I'm assuming that I should trust in the new Mopars readings. Thoughts?? If this is the case then I would prefer my XJ to run in the low 190's rather than the high 210's. So what do you guys think?? I'm planning to do a full flush soon but do you think an Aluminum Radiator and a possible electric fan setup would be worth the investment??
Thanks!!
I'm assuming that I should trust in the new Mopars readings. Thoughts?? If this is the case then I would prefer my XJ to run in the low 190's rather than the high 210's. So what do you guys think?? I'm planning to do a full flush soon but do you think an Aluminum Radiator and a possible electric fan setup would be worth the investment??
Thanks!!
CF Veteran




Joined: Aug 2019
Posts: 1,473
Likes: 270
From: Littleton, CO
Year: '96
Model: Cherokee (XJ)
Engine: 4.0 HO
Old sensor was possibly filthy and worn out. Electronic components dont last forever. But yes use an infrared thermometer and see if the housing is the same temp as your dash gauge. And BTW, these motors are meant to run at 200-210 degrees for optimum performance. Below that and you may not be getting the full potential out of it..... Engine temp plays a roll in engine performance and efficiency.
CF Veteran


Joined: Dec 2016
Posts: 1,755
Likes: 415
From: Long Island, New York
Year: 2001
Model: Cherokee (XJ)
Engine: 98 stroked 4.7
Take your new sensor out and and drop in a pot of boiling water keeping the elec part dry...after a few minutes should read 625-725 ohms... do the same for the old one see how much it differs. Mine reads 675 which is dead center on the fsm charts...when I dial 675 into the wiring harness...my gage goes dead 210
CF Veteran




Joined: Aug 2019
Posts: 1,473
Likes: 270
From: Littleton, CO
Year: '96
Model: Cherokee (XJ)
Engine: 4.0 HO
I live at 5,351 feet. Boiling point drops to 180 with just those extra 351 feet.
JK. I actually think that boiling up here is about 202 or 204. I did measure it one time........................ Hang on....
Yeap internet says 202 degrees.
JK. I actually think that boiling up here is about 202 or 204. I did measure it one time........................ Hang on....
Yeap internet says 202 degrees.
Last edited by RockyMtn96XJ; Mar 3, 2021 at 12:37 PM.
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As for electric fans - we usually do a triple 10 inch radiator + fan layout. Again does the job with zero complaints, unless you are riding in Mexico ,, then I'd say we take 1 of the 3 fans and bump it up to a a super high capacity one.
Disclaimer : This is not a sales pitch.. just my 2 cents!
Michael
Radiator Express
Thread Starter
Senior Member


Joined: Apr 2009
Posts: 819
Likes: 7
From: VA
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
I live at -20 ft below sea level so what would that equal out at? 180°?
Thread Starter
Senior Member


Joined: Apr 2009
Posts: 819
Likes: 7
From: VA
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
I will definitely break out the temp gun and get a reading tomorrow.
Not sure on the boiling water tho. Do I leave the sensor plugged in or do I take it out and use a DMM to take the readings?
Not sure on the boiling water tho. Do I leave the sensor plugged in or do I take it out and use a DMM to take the readings?
CF Veteran


Joined: Dec 2016
Posts: 1,755
Likes: 415
From: Long Island, New York
Year: 2001
Model: Cherokee (XJ)
Engine: 98 stroked 4.7
VA is the same as Long Island 212 ballpark. You have to take it out and do the boiling and readings in the kitchen with a DMM. Its a little easier if you can make up some jumper wires for the terminals in the sensor...easier to hold /keep out of the water and read with the meter. By the time you bring the pot of water outside ..its not 212 anymore but you still have to have the sensor removed. . I don't have a infra red thermometer so I cant vouch for the accuracy but give it a try and see what it reads. You can aim the thermometer at the boiling water in the pot...see what it reads also.it will tell you how accurate the thing is
Senior Member
Joined: Aug 2020
Posts: 614
Likes: 205
From: Prescott, AZ
Year: 1988
Model: Cherokee (XJ)
Engine: 4.0
I find the IR thermometer decently accurate if you can shoot it right on the metal part of the thermostat housing next to where the main hose goes to the radiator. That's as compared to my Subaru where the housing is plastic and on the bottom of the motor so this isn't an option...
Thread Starter
Senior Member


Joined: Apr 2009
Posts: 819
Likes: 7
From: VA
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
If you want to go all aluminum, I'd suggest stick with a 2 row. upgrade SKU 221504 They are 1 3/4 thick in the core and designed to be stock fit / flex with jeep movement and they do a really nice job cooling. We sell a lot to desert crawlers and have had zero complaints on cooling capacity. For a $200 investment, it's well worth it.
As for electric fans - we usually do a triple 10 inch radiator + fan layout. Again does the job with zero complaints, unless you are riding in Mexico ,, then I'd say we take 1 of the 3 fans and bump it up to a a super high capacity one.
Disclaimer : This is not a sales pitch.. just my 2 cents!
Michael
Radiator Express
As for electric fans - we usually do a triple 10 inch radiator + fan layout. Again does the job with zero complaints, unless you are riding in Mexico ,, then I'd say we take 1 of the 3 fans and bump it up to a a super high capacity one.
Disclaimer : This is not a sales pitch.. just my 2 cents!
Michael
Radiator Express
Verifying the temp has been suggested multiple times. Do it. Get an IR thermometer and verify the temp. Could be the sensor, the wiring, and even the gauge. Or none of the above and all is well.
Parts cannon locked and loaded lol.
Last edited by fb97xj1; Mar 5, 2021 at 12:11 PM.


