2001 XJ w/ 275K miles..

On the highway and 35+mph (when the air is moving) it runs about 175 degrees (installed thermostat temp). BUT I also noticed it will creep up to 210 on the highway on longer road trips when I'm running it too hard in the Texas heat

I don't have a problem with it over heating but it will break 210 -- I haven't put an infared on it yet but I'd assume it's hitting 220 +/-

Here's what I've replaced/repaired:
Water Pump
Thermostat
Radiator
Flushed cooling system
Fan Shroud (b/c the old was cracked)

I was told by the previous owner that the fan clutch was recently replaced and it seems to be firm enough -- The electrical fan definitely works too.

Any help would be appreciated... I feel like the previous owner had some problems with this and got tired of chasing it down.. I've checked the radiator for exhaust gasses, no coolant anywhere on the 0331 head (yeah that sucks), compression is good, and it seems to be a solid motor so I'm thinking its something else...

Thanks,
Jesse

 

PO could be wrong. classic symptoms of a bad fan clutch. Not to mention the Chinese Replacement Auto Parts we get today aka CRAP.

 

210 isn’t abnormal I’d say you’re running like it should be .

 

Low/no speed overheating is typically an airflow issue. 210 is normal temps for the 4.0L. Infact you should remove that 175 thermostat and replace it with a factory 195 T-stat. Running at low temps does nothing but burn more fuel and cause more wear.

You're current parts replacement list only addresses water flow with exception of the shroud. I'd say replace the fan clutch but your temps are pretty normal.

 

Key words: FACTORY STAT.