thermostat housing?

 

That's where I expected to find it but it's not there. There's a hex head plug in a port on the left side of the thermostat housing. Could be why it doesn't work, huh? Maybe the PO broke the sender wrenching around in that area and put a plug in the port. There's an unhooked electrical plug that's about the right length to reach that area, but it looks like it's a 3 prong affair. That seems like a lot of wires for just a temp gauge.

 

Could be different from mine, but on a 95 efi 2.5 it's where one is

Couple photos

https://www.dropbox.com/s/0um0r6wgt7c8lbv/Photo Jan 05, 11 49 34 PM.jpg?dl=0
https://www.dropbox.com/s/pwvzr3nijf7j9c6/Photo Jan 05, 11 49 53 PM.jpg?dl=0

 

Usually the sensor on the thermostat housing is the coolant temp sensor for the computer.
The Sender for the gauge is somewhere else. On the '89 2.5L look a few inches aft of the throttle body and slightly toward the valve cover screwed into the manifold

 

Ok...I found that one. It looks like this...

But I'm curious...if that's the only one I can find, does it also do the sensing for the computer? I don't wanna mess anything up by removing it. The problem with the gauge currently is that the needle just barely moves but a digital thermometer shows the engine to be at a normal temp. Maybe I should just replace this sender and see if the stock gauge works better. I work in the parts dept of a CaseIH dealership and it seems like about 90% of the time the sender is the problem with our stuff.

 

I have to do more research. I quickly paged through my 89 fsm and it wasnt mentioned but once. I dont have an 89 2.5L to look at. On some the 4.0Ls, they have a separate sender for the gauge at the DS rear of the head. Others show a sender/sensor on the DS of the side of the block. Look down there for something.

I had an 88 MJ and wanted to put a mechanical temp gauge in where that plug is in the thermostat housing. That sender bulb wouldnt fit depth wise. Ive seen them in the side of the block, but they read a bit too cool there as thats where the cooler radiator water hits first.

 

I have a 89 with a 2.5 - it is on the top of the back of the head on the drivers side for the gauge.
there is also a coolant sensor in the side of the intake manifold that the computer reads.

 

On the newer 91-95 2.5s they moved the coolant sensor into the thermostat housing from the intake manifold.

 

Ok...if the one I found is for the gauge, I'll look for the computer one in the side of the intake manifold tonight when I get home...to make sure I don't screw something up.

thanks

 

Here we go, funny thing is that came out my 94-95 parts book and it's clearly not located there on mine

 

Intake manifold. If i remember correctly the intake air temp sensor is almost identical so pay attention to be sure tou pull the correct one lol its right there by the throttle body.

 

Hmmm...so the one on top of the intake manifold is an air temp sensor. That makes sense, because I was wondering why there would be coolant right there. Guess I would have figured it out when I removed it and it was dry. So is the one on the side of the intake for the gauge or the computer?...or both?

 

One on the side (#16) is for the computer. The one for the guage is on the back top drivers side of the head. Also if u need to burp the block a helpful tip is to back the jeep up on a slight incline and fill it up with the coolant sensor out. It gets all the air out of the engine real quick that way.

 

Ok...got it. I'll look for that one.

 

:thumb::thumb::thumb:

 

Found it. Right there on top of the head like you said it was. Little bitty sucker...I was expecting something larger. (heard that before ) Lots of gunk on it and the plug was almost pulled off...it may just need the connection freshened up a little.
Thanks for the help

 

Np bro make sure you clean it really well and make sure the plug goes on there tight aswell

 

Cleaned the post and plug, tweaked the plug a little for tightness and it works perfectly.