Hey everyone..
Just curious if this is all correct... My 91 XJ seems to run about 215 at all times, sometimes when sitting at a long light it will start creeping up on 230 , The E fan appears to kick on at about 217, I plan to take it out to the desert this season and just want to make sure those numbers seem about right. All my other vehicles run about 180 and I start to worry when I see them at 210-up. Are these Common numbers for these 4.0 XJ's
Thanks!

 

That does not sound good.. I've had heating problems with mine so I decided to replace my radiator and add higher coolant ratio to water and its working great for me. I have an 01 but it's still the 4.0. My temps are running right about 180 even on a hot day. Check for any sort of leaks in the hoses too.

 

a higher coolant:water ratio will make it run warmer. water displaces heat much better than coolant.

 

Out of curiosity, what temp t-stat r u running?

(water displaces heat slightly better than coolant)

 

What r your current ambient temps? If they r cool/moderate, 215 sounds toasty. Might want to verify coolant temp or correct the situation if 215 is accurate. If 215 is correct and nothing is done, hot desert temps may cause undesirable issues. The XJ cooling system is not to be taken lightly.

 

sorry about that. Meant to say higher water to coolant. Been a long day.

 

Bad Luck XJ, what temp t-stat r u running?

 

Stock. I haven't tampered with it at all. I'm pretty sure it's giving me the right readings on it.

 

Get a new viscous fan clutch if not bee done recently. Ignore whether its "testing" out ok.
You will me amazed what the effect can be in slow moving traffic or on your situation sitting idling for a traffic light.

 

There are a few simple rules for the XJ's cooling system:

1. The minimum temperature you should see is 195 degrees, once warmed up.
2. The electric fan will turn on around 218 degrees.
3. The clutch fan does the majority of work.
4. The in-dash gauge uses a totally different sensor from the PCM in 1991.
5. The automatic transmissions discharge heat into the radiator.

#1 and #2 give us a normal healthy operating range of 195-218-ish. 210, or just top of the gauge, is quite typical for all model year 4.0Ls.

Cooling system component life is limited and often ignored. The XJ's system is marginal as it is so it's basically impossible to waste money in it. That said my first suggestion is to just change the coolant and verify that the gauge in the cab is even accurate.

 

Something is not quite right......stock stat is 195F so running "180F even on a hot day" means either the gauge is wacked, the stat is not a 195, the stat is wacked, maybe even missing.

 

Thanks for all the info, I think ill start with a coolant flush and see where im at, I did use the therm gun and the gauge seems to be accurate, after the coolant flush ill do tstat.. im debating putting a push fan on the front of the radiator anyway just for extra help..

 

My 91 XJ runs almost to the red on a hot day in the desert but never boils into the overflow tank. I believe my gauge is off about 40 degrees.

 

Wasn't necessary in 1991, if the cooling system is functioning correctly, shouldn't be necessary now.

 

interesting. I will look into that right away.