I replaced my dash cluster that had the dummy lights in my 1996 with a cluster that had actual gauges, I was able to get the oil sensor replaced fine. but the temp sender is kicking my a** I cant get a tool in there well enough to get it all the way down. its not leaking atm but my temp reaches red line with in 4min of idling and wont go back down even when driving. I get no other warning lights or anything with it. I believe I just don't have the sensor in all the way and its not making good contact with the coolant. are there any recommendations on the best tool to get this sensor seated well?

 

a 12mm open end spanner is the only tool that will work imo, if needed, buy a $1 auto parts special and cut it short

an XJ Cherokee should be properly bled overnight imo, otherwise they can overheat.

 

How do I properlly bleed overnight?

 

I was able to get a deep socket on the sender on my 95 with a wobbly extension and it came right out. The plastic part on the old switch disintegrated when I went to remove it.

The system should bleed itself after a few days of driving/checking/filling. I always open the radiator cap, fill it up, run it until it reaches temp, top off, let it run for a few more minutes and top off again then make sure the reservoir is full and check it periodically over the next few days.

If you're getting red line temps, I would want to confirm the temp with an IR gun to make sure that the engine isn't -actually- overheating.

Also, if the wiring is bad, the gauge will spike, but what worries me with your description is that it takes 4 minutes of idling to get there... a grounded out wire would spike from the moment you started it up.

 

I got a socket on the old one, but the new ones nut is to big once I get it hallway in its to close to the valve cover.
I will be getting a IR gun this weekened but after the 4 min and my temp is red lined I can still touch the radiator, exhaust manifold and the coolant hoses. that's why I believe I'm getting false readings.

 

If you touch the valve cover or block, does it feel hot? Touching is maybe not the best idea, but maybe hold your hand over the area..

Several years ago I was on a road trip MA -> VA and upon entering MD my TJ overheated, radiator seam busted, etc. etc.. Long story short, the plastic impeller on the water pump had sheared clean off - however, because the weep hole was dry and there was no bearing noise (and it was a recent, but not immediately recent replacement) it was the last thing on the list of suspects. From all appearances, the water pump seemed to be fine. I only even went to replace it because it was literally the only thing that hadn't been doubly verified.
The reason I mention this is that 4 minutes was right about the amount of time I could run the engine from a cold start before it started creeping up past the 210 mark.

Do I think that's what's going on with your XJ --- not really, odds are it is just false reading -- but is it something that would cause the behavior you describe - including radiator and hoses being cool enough to touch - absolutely.
Therefore, I'd want to verify the temp before I drove the Jeep anywhere. A water pump is a relatively easy and inexpensive replacement.. a cracked block, not so much.

 

my thoughts have been if its not a false reading and its true. then its either a thermostat or the waterpump. ill double check the temp by feeling near but not touching to see if there hot.

 

Definitely not trying to scare you or anything, just would hate to see anything happen to your Jeep.

Another possibility is just a simple "bad out of the box" temp sender. I'm assuming that it's not a Mopar (when I did my cluster swap the old switch was the metric 12mm, the new STD brand was like 9/16 IIRC) and even if it were, quality control has not been optimal in recent years - especially for older Jeep parts that are made in China.

 

Try loosening the sensor and seeing if coolant comes out. You may have an air pocket in there and it will bleed out when you loosen it.

 

pathenr- that's what ive been seeing on forums also..i bought a autozone special <https://www.autozone.com/engine-management/temperature-switch/duralast-temperature-switch/190451_0_0?&searchText=tu236> that one

dave1123- I will give that a try tonight!