2000 XJ - I know there is a temperature sensor that threads into the thermostat housing...there is another one in the back as well right?


Where is it?
Are they the same Part number?
Which one does what?
Any issue putting a $15 one in vs a $30 one?


I overhauled my cooling system and am getting temperature creep at idle. Radiator, flush, water pump, hoses, thermostat, burped etc. Yes the fan clutch works. I'm beginning to think it could be the sensor giving a false reading. My needle creeps up past the 210 mark (Sometimes between the 210 and next hash mark) and using my Bluetooth OBDII I am reading 208-210.2 driving but then at idle I get temps 218, 221 and 222.


Twice I watched the BT OBDII in the driveway and at 221 the e-fan did not engage right away...yesterday at 222 driving and I did not hear it engage, but the fan does work. It has not been hot here in VA either. I installed a fan switch yesterday but am wondering if one or both of the temp sensors should be replace and/or the relay.


I don't want to keep throwing $$ at it. Id like to replace the e-fan because it is noisy anything produce more air and reasonable priced? any particular size fan to fit the space?


Thanks

 

The gauge sensor on a 2k is the one in the t-stat housing. 96 and prior had the gauge specific sensor at the back of the head.

Get a Mopar if you want to be confident that it's working correctly and will last. Napa premium would be the 2nd choice. I would get the better one - is questioning the sensor or not worth $15 to you?

 

2000 & 2001 XJ aux fans turn on at 223 degrees. The computer is reading the same OBD-II temperature you are.

 

No doubt the extra $15 is not an issue if its only 1 sensor vs 2. When I pulled the old sensor from the housing it had some scale build up on it. I wire brushed it off - think that could have messed it up. Should I consider the relay? Any other direction you can think I should look ...I just don't think with 70-80 degree weather and essentially an overhauled cooling system I should be creeping like that.


Also it seems to take a while for the temp to drop back down even when I get back up to driving speed.


Think I should move the trans cooler over to one side or the other instead of the middle? could it be blocking air flow? I used spacers to keep it about a quarter inch from the condenser.


I may just be grasping at anything here.


Thanks

 

Your trans cooler shouldn't be an issue. Mine is right in front of the main fan and I have no cooling issues, even towing.


From your original post, it sounds like your gauge is displaying what the sensor is reading confirmed by OBD-II. To fully confirm the sensor reading, take a reading at the thermostat housing with an IR thermometer gun and compare that to OBD-II.

 

I have an IR in hand as we speak and am testing as soon as i get home. Thanks.

 

How do you know the fan clutch is working?

 

I had a relatively new mopar on. After my overhaul when I was getting creep I went ahead and put a new NAPA one on just to rule that out since symptomatically it seemed like a bad clutch

 

Can't say I blame you for being concerned about the temp creep. Especially as cool as it's been (barely in the 60's here right now). Like Tbone my trans cooler is in front of the mechanical fan. Even at an extended idle with the a/c on my gauge will barely be past the 210* mark on a very hot day. Let's see what the IR gun shows.

 

Any particular spot on the thermostat housing to point it at? Obviously not a fin.. but about anywhere else I'm getting lower readings than my obdii. I'm going to test the ir with a lot of water that I have checked with a kitchen thermometer and I'll resume testing on the xj tomorrow.

 

Right next to the temp sensor would be best.