Once warmed up you should have pretty consistent heat and I dont believe that your gauge should be bouncing around that much.
I would take a look at the thermostat.I would probably just replace it given the fact that it is cheap and easy peace of mind.
Sorry if I missed this in your earlier posts but make sure your coolant is topped off with the proper mix of coolant/water.
Honestly to me it sounds like one of those two things.

Could be a combination of a couple of things,maybe the water pump is failing,maybe the t-stat is sticking like many have said.I would start with the t-stat though which has also been mentioned a bunch of times already lol just wanted to get my 2 cent in there. GL

 

Whats up XJ5150? im down here in mint hill, and my wife has a WJ, same motor, and its solid at about 210, and rarely moves if ever, i'd assume a bad thermostat, unless a fan is sticking on all the time

 

is it bad to run this cold? mine does to and i have electric fans that i rarely turn on unless im in stop n go traffic

 

155 is pretty low, the 4.0 likes to run hot. likely side effects are poor gas mileage(because its dumping extra fuel to heat up to try and get to proper operating temp), and a possible side effect is destroying your cat, if it goes on long enough

 

thats weird it idles normally around 750rpms i havent really noticed a gas mileage drop besides wat happened when i threw on my 32s lol

 

Mine sits at about the same spot... only moves up to the left of the 210 mark and then the electric fan turns on.. Mine never reaches 210 (on gauge). I think my gauge is just low on the reading... Checked with a temp gun a while back and the thermostat housing was 200 while my gauge was looking like the 182 mark. I'm in So Cal weather

 

You're just now telling us u lost the factory installed piece of card board in front of the radiator? That was a joke, just kidding.

With the temp **** pointed at HOT, u should have hot air blowing out where ever the vent selector **** is pointed, including the a/c position. This is presuming engine coolant is properly heating to and remaining at normal operating temp.

There's been some other posts in this thread saying "my gauge seems to run about where yours (the OP) does"....or something similar. That doesn't mean that yours is normal....that means there's something wrong somewhere with yours and theirs.

Again, if all components of the cooling system are functioning correctly, your using a 195 t-stat, your gauge is accurate.....the temp needle would logically be a tick below 210 and should remain very steady this time of year (maybe move +/- the width of the needle).

Tell us what u have, or have not done to the cooling system, maintenance wise. Technically, the heater core is not part of the cooling system.

 

is it serious tho? im bout to go on a 900 mile trip and ur makin me nervous now lol

 

Hello from Concord, shouting out to Charlotte.

I have done nothing to the cooling system other than top it off with water. I have not checked the mix or ratio of coolant in it though so I have no idea if I am running straight water but it is not clear in the reservoir, that I do know. Now that it is clear outside and not freezing, I will look it over a little better.

I did make a trip to Cape Coral Florida and back and the temp never gave me a hint that something was wrong. I do have the service manual in PDF format so I will read it over and see if it says anything in there about temps.

I should also state that the gauge does not bounce all over... When the engine is started from cold, the gauge slowly rises if I let it sit and warm up to just barely past the 210 mark. That's when it drops to just above the quarter mark on the gauge. If I stop at a light the gauge will slowly rise... usually to just between the quarter mark and the 210 mark. Once I start driving it drops to just above the quarter mark again. This seems normal to me because there is less air moving through the radiator when parked. My "belt fan" is fine and the clutch is working. The Aux fan also comes on... as a matter of fact, it comes on when the gauge hits just past that 210 mark.

There was cardboard in the Jeep when I got it... I was hoping it was the factory piece for the radiator... but alas, no Jeep logo so I threw it out lol Yes, I got that joke

 

I'll answer your ? with a ?........how long has it been since u did maintenance? Hope your 900 mile trip goes without incident in your 16 year old XJ.

 

What I meant when I said bouncing around is when it goes from 210 to 155,sorry I should have been more clear.
I am still learning jeeps my self so can't say for sure I guess but general knowledge of the workings of automobiles and experience working on them tells me that your temp should not be fluctuating that much unless there is an issue.
I would venture to say that the reason the temp drops so much when you are driving is due to the higher rpm's circulating coolant faster with an open thermostat and when you are stopped there is slower circulation so the temp is rising.

Check your thermostat and I would do a cooling system flush and put the proper mix of coolant in your jeep. Antifreeze is not only for freezing protection but also boil over protection. Water only will not cut it even if you are in a warm climate.

 

You've done nothing to the cooling system.

If all was normal (as u say), why would the gauge go past 210 in this freezing cold weather?

If all was normal, why would the gauge drop to 155 with a properly functioning 195 t-stat (t-stat maintains minimum coolant temp)?

Again, to answer your initial ?, where your temp gauge is pointing, in your pic, is not normal.

This is what we're doing, right?

 

oil change about 1000 miles ago if that
spark plugs and wires a little longer then that and im about to put a new air filter in before i leave

 

That's a mighty short list. Be safe.

 

It was a little warmer today...



This is right when the temp dropped... I just sat there in the driveway waiting for the engine to heat up... it got exactly to this point and dropped. This time when it dropped it stayed above that 155 mark as indicated in my other pics... I am guessing it HAS to be a 192 tstat. This thing cant make up it's mind when it wants to open or what temp it want to chill at. Guess I will have to suck it up and replace the tstat and flush the coolant. Ughh!

No, we aren't fighting... I call this a decent thread. I am happy you have posted.