I am more confused than ever I have a 96 and a 99 and each has the pcm sensor at the front and the gauge one at the rear the sensor you show hanging down where did the factory put that originally

 

My apologies! I have the same sensor locations as you do. I have the pcm sensor at the thermostat housing and the gauge one on the rear driver's side of the head that the photo shows just "hanging out" because the threaded hole it belongs in is blocked by a hardened allen headed screw. So my post was to see if there were any ideas about another location where I could install the gauge sensor. Hope that clears it up for you, in post #3 I put up a pic of the original location for the gauge sensor after I broke off a allen wrench in the head of the screw.

 

I have '96, and (from memory) they have 2 sensors. one at rear, one in the thermo housing

I have found from past experience on another vehicle that a tee for coolant temp is unsatisfactory, as it will not read the coolant temp accurately

If I was you, I would drill and tap the themo housing for a second sender if that is possible, as the thermo housing is a cheap part to replace if you screw up

 

AWG, you are probably right. I was thinking about what cruiser54 said, "Use a tee that guarantees that the tip of the sender is well submerged into the path of the coolant."
I am having a hard time thinking about how to make that happen with a "T" coupling on the thermostat housing. I have a banged up spare thermostat housing that I can get out for a test dummy to see if I can get another hole drilled in without interfering with the others!
Thanks for that post!

 

In the picture you show in post #7, flat spot next to the mounting bolt; installed mine...

 

Which picture Jim first or second? Also which mounting bolt?

 

The best way would be to use the correct spot, and I know you said you had already broken an Allen key, but I have found a trick with stuck dissimilar metals is give them repeated heat/cool cycles. so I would use a butane torch to hit the plug, and let it cool down, do that quite a few times then try again. You can use penetrant to cool
If you can get an impact gun on it, that will also increase the chance of success

 

Yep, that is the classic way to remove a stuck fastener. With the engine installed and access being limited by the cowl overhang there are limits to what you can do and what I am going to do. That is why I was asking if there was a suitable alternative to the location of the gauge sensor. For now, I will move on to other things I can do. I have several rusty spots along the drip rail that need attention, a couple in the passenger floor, need to get the front clip assembled and need to check the front and rear differentials. I have been pulling coolant temps after the XJ has been running a while, with and without the AC from the bluetooth OBD sensor I hooked up. It is managing temps pretty well with no road speed to increase airflow and a higher then normal rpm which is a cause for high temps. Hopefully, once I am further along I can revisit the gauge sensor problem. Or if my buddy the welder has some time maybe he can weld a not onto the screw and we just take it out. I can weld but don't trust my skills in that area right now! He can weld anything but the crack of dawn or a broken heart!

 

First picture in post #7, showing the thermostat housing and the crank pulley. Between the top-most mounting bolt on the left of the image and the sensor on the right, directly below the heater hose outlet is a large enough flat spot to drill and tap for the gauge sensor.

 

Good eye, Jim. At first chance, I will take my spare and see how it goes, thanks!

 

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