I wanna work on my heat issues this weekend, so I'm going to do the CLR cleanse with an air compressor and reverse flow and all that, but I also may have an issue with my thermostat in that my operating temp never gets above the 200° mark. Even in the summer and running on the highway. So I'd like to know what T-stat is in there, if its a 180°, or a 195° that's not working properly. I guess if I pull it and its not labeled, I'll just replace it anyway since I'll have the old one out. My concern is that the previous owner was extremely meticulous about the maintenance of this XJ, and it is in wonderful working order (except the blower motor switch not working on high, so I'll be replacing that as well). So I'm guessing a low temp t-stat or a failed t-stat. I'm fairly certain he said he changed the t-stat within the last couple of years, and the coolant looks amazing.
I guess the point of this is wondering if T-stats are labeled with the temperature hahaha...

 

Here is a post I put up last summer concerning my coolant temp. I realize now that the 200° mark I spoke of is actually the "210°" mark, but either way I feel like that's not even the spot the needle would sit at if the coolant was at 200°... I'm going to use my laser pointer temp gun to test the temp of the t-stat housing later today...

https://www.cherokeeforum.com/f2/pic...l-temp-253785/

 

210 deg. Is what my 1996 and my sons 1998 xj's normally run

 

Do you have a sender at the rear side of the block--drivers side kind of in-between the curves of the valve cover 3 inches from the back of the motor -ish...or is your sender built into the tstat housing sender? Early 96 had the 2nd sender late 96 has only 1 in the front that feeds computer and computer feeds gauge...the early has the back sender feeding the gauge. If you can't see the back sender...its pretty small and buried...warm up the jeep and pull the connector off the front sender... start truck...if your gauge drops to the bottom low temps then you have a late model system...you will throw a check engine code. The reason for this is the trucks with the sender in the back will show a cooler temp then the ones off the tstat sender because the water still has to travel to the front of the engine and it picks up more heat as it moves fwd...where it now hits the tstat.....the hash mark before the 210 is 180-185.. What im getting at is the trucks with 2 senders will show cooler than the ones with 1 even though the t-stats are opening at exactly prescribed temps hope that helps

 

So I'm a good bit on the low side... The guy I bought it from spends the summers in the Denver area, and the rest of the year in FL, so there may very well be a 180° or so t-stat in my jeep he put in due to the much warmer summers there... although, it only feels warmer in FL because of the humidity. Denver doesn't get above about 20% humidity unless its raining, but can still be in the 90's in the summer so I should be reading at or just below to 210° mark on the gauge.
Does anyone else have an idea why my temp gauge isn't indicating a higher temp? Could the temp sensor not be working 100%? I'm not quite familiar with the sensors in these jeeps yet and how they could fail. Would they just go out all together or just start acting up? Or I could just be back to a crappy t-stat that needs replaced. Or is my gauge acting up?

 

You answered as I was typing up my last post... I'll check and see what I have when I'm leaving work in a little while. But thats some good info!!! I'm also going to use my laser pointer thermometer thingy when I get home and see what the temp of the water is in a few spots along the route. Radiator cap, t-stat housing, heater core hoses, and possibly near the sending unit where you described...

 

I was in error...you have the old school gauge like in my long gone 92...My 01 has 2 more hash marks than yours one is below the midway line between the 100/210 and one above it...The midway line is around 160ish...remember the higher you go there are less temps jammed into the same area than the lower levels...60 from 100 to hash mark but only 50 from hash mark to 210 so 10 deg range takes less space at the top....first thing is to figure out how many senders...do you have a multi meter (ohm) and know how to use it...Does your truck have obd1 or obd 2...your are a little cooler than desired for winter but not horrible...and yes...most thermostats have a temp stamped on them either on the body or on the copper button that points away from radiator

 

Why would I have a multimeter and not know how to use it? Just kidding... I'm OBD-II, so would that be a late year '96? What resistance would I be looking for and where?

 

I have a pretty strong electrician background... aircraft avionics and RF stuff for satellites.

 

Ok good...if you have a decade box...even better...but in the morning when the jeep is totally cold...take a reading of the intake air temp and the coolant temp thru an obd 2 reader...they should be very similar....still need to know what feeds your gauge.....Delta avionics...

 

Maybe I can borrow a decade box from work over the weekend.... doubt it hahahaha... I suppose you'll get into resistance readings once I let you know about the numbers of senders I have... Speaking of which, I didn't get a chance to get outside and check on the number and locations of sending units last night. Wife said feeding and bathing kids was more important hahahaha...
Haven't got my own OBD-II reader, but I can try to use my IR laser gun to get some readings inside the intake tube and a couple places along the coolant hoses and whatnot. I have been meaning to get one of the blue-tooth BAFX OBD-II readers and download the torquePro app... maybe I should order one NOW.
Air Force F-15 & F-22 avionics, Lockheed F-35 Avionics, Lockheed Micro RF test and tune on satellites

 

I was just looking online and some decade boxes are reasonably priced. Not sure about the quality.. The ones we use at work are like thousands $$$. Of course I didn't fork out the big bucks for my DMM either. No Fluke, just one from Home Depot or Lowes or something... but its got all the functions!! Matter of fact, I do have a T type thermocouple wire at home, but I really dont think my DMM will take it. Wonder if the multimeter will do temp with regular leads??? I actually haven't paid that close of attention, just use it for ohms and AC/DC...

 

its kind of irrelevant what the actual temps are...its more imp what the sensors read.....on a cold truck the intake temp and coolant temp should be the same on the obd reader...If they vary by much then one of them is off....its possible that they can match cold...and be off when hot .....Wht I do is remove the suspect sensor and drop in a pot of boiling water...then take the resistance reading while its in the boiling water...its the only temp you can be sure of and then compare its reading to the service manual chart...I then use the decade box to plug in the manuals resistance values into the harness to see what the gauges read ...it verifies the wiring and the gauge...the decade box is great for tricking the computers into reading what you want

 

That's an amazing troubleshooting technique...!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I just ordered the BAFX OBD-II Bluetooth code reader/scanner/clearer and it will be at the house tomorrow via Amazon. $20.99 after tax. Will download the TorquPro App which is like $5 or something from the playstore, and then I can see the air and coolant temp together. It has A LOT of functions to see all kind of parameters about the vehicle you plug it into, and it can be used on several vehicles, so it doesn't get VIN locked. I hear a lot of people say good things about this product and the app to use with it. Heard about it from some guys here at work.