The popping could be caused by the overheating issue. Have you been brave enough to drive it to see if it cools down?
Could be a bad water pump, bad thermostat, clogged radiator or a combination of things.

 

I will check those things tomororw and no I haven’t driven it yet bc j was afraid of blowing the motor. Thank you for the suggestions I will check them out tomorrow

 

Sal, do you have a gauge or a "dummy light"? If you have a gauge, what is it reading? (In other words, what exactly do you mean by "overheating" - creeping up past 210 a little or is it going towards the red lines?)

Have you checked your coolant level (in the radiator as well as the overflow tank)? Is the coolant a nice solid green color (assuming it's regular old coolant and not one of those pink or orange deals.. )?

I would recommend buying an infrared thermometer - this is crucial if you have a dummy light and important even if you have a gauge (to verify the gauge is reading correctly.. though in your case you're experiencing additional symptoms that confirm the temp is -actually- too high and not just a wonky gauge.)

 

Ok you just trying to warm it up? how cold is it were you live ? was your radiator frozen ?

 

The popping noise is one that should be easy to locate. And might be the easiest to start with.

 

First thing... are you sure the reading is correct? The popping sound may be air bubbles, if you let it run for a while can be disappear.
Second thing, the radiator is ok? It's may be leaking liquid, or is clogged. Once you're sure the coolant is in the system, it can be a faulty water pump, or the thermostat

 

Well I learned one technique that I only used on an Acura RSX which could not be any further from a cherokee but it is worth a shot. Besides replacing the temp sensor. So this is what you can do to clear air out of the system. Pull off the radiator cap before starting the engine. Then Start the engine and put it on full heat in the interior. If you have air in the system you will start to see bubbles as the coolant overflows//it should overflow. Keep it going to remove all bubbles. Refill each time it overflows and if you have no bubbles anymore you know at least that part is solid. This may not be the solution to your problem but it is good to get the air out of the system. Wish your problem was this but I think it may be something else. Good luck!

 

Seeing as how we don't have any information on what year he's talking about, could it be possible it's a cracked 0331 head? My crystal ball is foggy today, LOL!

 

It's the same process on the XJ as you describe. The only additional steps that folks will recommend would be squeezing the hoses and parking the Jeep at an angle such that the radiator cap is higher than the rest of the system.

I've always just done the standard run it and add coolant until it won't take any more and the engine is up to temp.

 

I did forget to mention squeezing the hoses, mainly the big boys up top. Good point! I also never thought to park at an angle such as that. Amazingly I did this to the little RSX and the heat did come back. That system is very sensitive. My jeep cooks like an oven so I never had to worry about it. Thanks for the extra pointers!

 

I've found the absolute easiest way to fill a 4.0L cooling system is to remove the temp sensor by the thermostat, fill it up until coolant runs out the hole, put it back in, and continue filling it. Start it up and wait until it starts bubbling and add until it won't take anymore, cap it, and fill the reservoir. Shut it off and let it cool. If the reservoir drops any after it cools, add to the reservoir only. It's worked without fail on my 97 ZJ and my 2000 WJ.

 

 

as an extra special measure, cut a big plastic drink bottle makes a kind of watertight funnel into the radiator neck, with Jeep parked on steep incline or ramps,
heater open, pump hoses, use funnel to keep rad continually over filled. My mate who is a cooling system pro reckons XJ are a nuisance to bleed

to the OP, one time I had similar situation, engine would boil over nearly straight away, ended up being an internally fractured radiator cap

has anyone mentioned thermostat failed shut

 

FWIW I always drill an 1/8" hole in the t-stat base to aid in purging off any air. Obviously an open t-stat is much easier.