What temperature does your XJ typically run at?
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Easy. 50C is halfway between the points where water breaks **** and stops moving, and is liable to violently explode. It's also roughly 1/3 hotter than us fleshbags.
Your Jeep will be fine if maintained. The 4.0L is a bit big (in terms of thermal load) for the thing in the first place but the system works. Above about 215F a LOT of things kick in. People see 205-210F as their normal operating temp and think "Wow, only 30 degrees to go! Nice margin". Not so simple. All of the cooling system components have a range of capability which is engaged more as the temp rises. For example the thermostat opens more, fan clutch engages more, and if it had to the PCM flips on the aux fan. The XJ's ability to reject heat is NOT linear.
So make sure the stat is good, clutch fan is good and shrouded, and cooling system is air- and gunk-free and you'll be fine.
That said automatic transmissions screw all that up in a hurry by dumping their heat into the radiator. Loads like trailers and big tires without different gears are the main problem.
Well then. Lol
Your Jeep will be fine if maintained. The 4.0L is a bit big (in terms of thermal load) for the thing in the first place but the system works. Above about 215F a LOT of things kick in. People see 205-210F as their normal operating temp and think "Wow, only 30 degrees to go! Nice margin". Not so simple. All of the cooling system components have a range of capability which is engaged more as the temp rises. For example the thermostat opens more, fan clutch engages more, and if it had to the PCM flips on the aux fan. The XJ's ability to reject heat is NOT linear.
So make sure the stat is good, clutch fan is good and shrouded, and cooling system is air- and gunk-free and you'll be fine.
That said automatic transmissions screw all that up in a hurry by dumping their heat into the radiator. Loads like trailers and big tires without different gears are the main problem.
Well then. Lol
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
CF Veteran
Joined: May 2011
Posts: 6,098
Likes: 250
From: DE
Year: 1988
Model: Cherokee
Engine: I6 4.0
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
In 4 seasons worth of driving, the ScanGauge will show a coolant temp hi-lo range of 175 to 230. The ScanGauge shows the same hi-lo coolant temp range throughout 4 seasons of driving in our other vehicles as well.
Last edited by djb383; Nov 25, 2014 at 12:10 PM.
Junior Member
Joined: Nov 2014
Posts: 36
Likes: 0
From: Imperial Valley Ca.
Year: 1996
Model: Grand Cherokee
Engine: 5.2 V8
My 96 XJ 4.0 usually runs at 210 or a little less on dash gauge. Installed mechanical gauge and reads 20 to 30 degrees cooler than dash. 180-190. running 180 degree thermostat and GC fan clutch.




