Hello fellow XJers, I'm noticing now that it's 92 degrees in Denver today and with my AC on, my jeep runs hotter, which I expected, but I didn't expect this hot. Is this too hot and signs of overheating possibility? 98 4.0 210K miles. New radiator and water pump last year. Coolant level is correct and is bright green. Am I being paranoid or could there be a problem. Pics were in park idling, AC on.

 

My 98 runs that hot in stop and go traffic in NYC but normal driving I am under the 210 mark.

 

2ND pic is just on the warmer side of just perfect. If that's the hottest she gets ever, don't sweat it too much. If it gets hotter stuck in traffic, wheeling, etc... Look at a good flush of the cooling system and a new thermostat.

 

I'm thinking maybe needs a new fan clutch, ZJ possibly? It didn't go above 230 letting it idle in the sun for a while, fluctuated between 228 and 230. Coolant is barley a year old, with some being replaced when I flushed my heater core and replaced upper hose last year. Thermostat was also done in October. Is it normal for engine rpm to rise with temp? it rose as it got hotter.

 

I wouldn't be comfortable with that. I feel like 215ish the highest I ever want to see coolant temp in any vehicle. does the coolant temp go down if you raise the idle to 1000-1200 for a couple minutes?

 

It will go down a little, maybe to 215-220ish.

Also forgot to add that going down the highway it cools down but still was above 210, granted it was 75 mph.

 

that evidences insufficient air flow, coolant flow, or both. when is the last time you replaced the fan clutch? I assume the elec fan works.

 

Update: Holding my rpm at 2200 kept the engine right at 210-215. Brought it down from 224. I also believe the water pump was replaced with the radiator.
Never replaced fan clutch, no idea when it last was, only had this vehicle since May of last year, e fan is new.

 

It is on the warm side, but 92f ambient temperature at over 5000ft above sea level is going to run a little warmer than stock. I would expect to hit 220f on mine sitting with AC on in 90f outside temperature (I was just observing this last week) but I am at 200ft above sea level. So I would expect a little higher for you. Not only are you pretty high in elevation, but at 90+ degrees your "density altitude" is very high, which basically means that the air has less oxygen by volume. Anything that radiates or moves air (like your radiator and fan) are going to be -less- effective than they normally would be.

Because higher elevations are typically also cooler, this isn't something that is normally very obvious. But when you mix high elevation -AND- very high temperatures it can make a big difference in anything depending on air to do its job (ask any private pilot that flies around denver in the summer, and they'll tell you).

 

So I replaced the fan clutch with one for a ZJ. I'll report tomorrow how it does. I did it amid thunderstorms and rain so that was fun. There was one casualty however, the shroud. Already ordered a new one.

 

This is spot on.

When I'm doing high desert wheeling in the summer, I generally turn off the AC and turn on the cabin heat. It sucks, but it makes a noticeable difference.

Also - keep your RPMs up when wheeling in heat. 2k seems to be a sweet spot on these machines, and the additional airflow and coolant movement will help ensure you keep temps down.

 

my xj has never gotten hotter than 210* if the efan is on. 800' elev and da in the 2-3K range at times. I think this one has another issue.

 

You could be right. And it is wise of the OP to check everything over carefully to make sure there isn't something else going on. However, Denver sits at around 5000ft (even higher if you head up towards the mountains) and at 92f temps, the DA can get very high. (quite a bit higher than what you mentioned).

 

Your temp is too high. It's only going to get hotter in Denver.
Get a JY shroud.
What brand thermostat did you install?
And did you replace the temp sensor when you did the radiator?

 

You need to verify the reading first. Get an infrared temperature gun and point it at the thermostat housing while watching the sensor reading. The sensors aren't the most reliable