I've been driving my XJ around ('94 4.0 AW4/NP231) and recently noticed that my aux fan is coming on a little more frequently than usual. I did a radiator flush last year and my coolant still seems pretty clean.

The Details:
Fan clutch seems good, still has resistance, doesn't keep running when engine is shut off.
Used a temp gun to take temperature (on radiator hoses) and seems to run nicely in the 200-210 range. (My jeep is bones -- did not come with temp gauge)
thermostat seems to be working. Water pump...don't know how to test it but I assume if its bad I wouldn't be running at a good temp.

SO, we have an engine running at normal temperature, with working fans and thermostat, and clean coolant. So far so good, right? Except the fan comes on almost all the time now, when it used to only come in when really hot or wheeling, etc. If I sit in traffic for 1 min it comes on, OR just seems to stay on at all times. It seems to me, and I'm no expert, that my engine is getting a little hotter QUICKER but then the cooling system does its job.

Anyone following my line of thought here? I ain't no expert, just a jeep man and a worrier

 

My old fan clutch had resistance but still gave me temp creep at idle...if it's the factory one I'd replace it. Now mine runs a tick under 210 even in the 90s with AC on in traffic.

 

thanks for the tip. I was gonna do a full cooling system rebuild but didn't wanna jump the gun without understanding what was really going on. Seems like I should replace the fan clutch first and then see what happens

 

I would. $35 or so at Napa. Easier than replacing anything else. I noticed my efan coming on at idle without the AC fan on when it was like 70 degrees out. Temp would hit 220. The efan comes on like at 218 degrees (unless it's cycling with AC).

 

I replaced my clutch fan from NAPA and it didn't do squat on my 2k!
Yes when hot, i can manual tap it with a couple inches of movement so i think its doing its job.

I remember my old '94 overheating when still relatively new while waiting in line to enter an air show. Had to turn the heater on to cool it down.

These engines run hot especially the later year ones.
On my 2K, numerous flushes, new pump, 3 new radiators...same 'ol same 'ol.

I got fed up with the hot weather overheating on my 2k and finally installed an aux. electric fan switch.
Now while waiting in line somewhere in hot weather when i see the temp starting to climb rapidly towards 210 deg. mark, i just hit the momentary push button switch.
After a minute or so the temp starts climbing down below to the thermostat's working temp.