You might want to check that pulse

 

I recently replaced the cracked radiator, had a rebuilt water pump installed and a 195 degree thermostat. The engine was running at 210, is now at a shade under 210. Runs fine at that temp. After driving any moderate time, when I park it, the temp rises to next line above 210. I restart, the elec. fan comes on and lowers it back down to around the high side of 210. However, it rough idles until it comes down to 210.
In stop and go traffic, it rises almost to the next line from 210.
This a 2000 Cherokee sport with approx. 220,000 miles.
Any comments or suggestions?

 

Sounds like you need a new fan clutch. The rough idle could be "heat soak" which I believe is common to your year XJ. Something to do with #'s 3 and 4 injectors getting hot and the fuel vaporizing? I think there's a factory part you can get because of a recall about the problem.

 

When you shut it off it is heat soaking and you are experiencing vapor lock when you restart it. The vapor lock is what is causing the rough idle--you have at least one cylinder "missing" due to lack of fuel. This is not that unusual. My 2000 does this occasionally, but only when it's been under a load for a while in 90+ degree temps.

The part that is unusual is the rising to the next line above 210 in stop-and-go. That indicates to me that your mechanical fan isn't doing its job. I would suspect your fan clutch is worn and isn't engaging as it should. Your electric fan should also kick on anytime you reach 223 degrees.

EDIT: Earl beat me to it!

 

99. Mine on a 95 or more degree day with ac blasting sits around 215 or 220. But thats with the temps on the radar saying it feels like 106 degrees or more. Make sure your cooling system is top notch and you shouldnt have a problem. But i go by the gauge inside and never tested or stuck an ir thermometer on it. But! i also havent checked my lower rad hose i think it may be worn out and restricting flow. It never moved past 210 until i busted my rad fan shroud and it is held together by zip ties and then changed the cooling fan. So when i get money im replacing those 2 things with a different fan this time. I ordered the more curved blade and i think that may be why its hotter than usual. But well see.

 

Hey at least we got our point across.

 

I got the point and it is really appreciated. I will get it replaced.
The rough idle at restart recall was to install a shield to redirect airflow around cyl.3 to keep debris away from that area. The recall was issued in May of 2002. IDK, but I check with local Jeep Dealers and see what I can dig up.
One more little thing... the piece of rubberized cardboard(?) that goes in under the radiator (I think) is torn and hanging down. Could this cause an overheat problem?

 

I think that recall was for an insulated shield that keeps exhaust heat from #3 and #4 injectors causing the fuel to vaporize.

Never heard of that radiator piece causing cooling problems. Really sounds like a fan clutch issue.

 

Mine is running at 210 to 220 and the thermostat has been removed. It also is a 2000 and the head is cracked. I will be doing a complete motor swap by the end of next year.

 

As everyone is saying it is a “heat soak” issue I also have a 2000 jeep Cherokee sport what I did was buy heat shielding for my injectors and I also wrapped my fuel rail to be safe. It’s super cheap and easy to do took me a max of 10 minutes to do

 

OK, So 210-220 is the target.

As I know my gauges are inaccurate, I'll use an IR thermometer to check.
I found various recommendations for my 87 Renix :

-> Thermostat housing
-> Radiator
-> Electric fan sensor

What is recommended to check temperature and if possible calibrate the gauge (by hand )

 

The normal thermostat is 195°F so the true operating temperature in the block is a few degrees below that. Remember that the temp sensor is in the thermostat housing at the top of the engine where the hottest temps will be found. My 96 and 98 show to be just below 210°F on the gauge. If we take the 4 hash marks on the gauge between 100 and 210 that means 110/4 equals roughly 28°F per hash mark. If my gauges are showing halfway between the last hash mark and 210, that's 28 X 3 +14 = 98°F. That plus 100 where the gauge starts = 198°F, which is in line with the 195°F thermostat. Yea, it's close to the 212°F boiling point of water but that's why we use coolant (Glycol) and keep the pressure in the radiator through use of a pressure-relieving radiator cap. Pressure serves to raise the boiling point.

Check this link to get an idea of the relationship of water's boiling point relative to the presence of coolant and pressure -

https://durathermfluids.com/pdf/tech...ling-point.pdf