I have a 95 XJ w/ 4.0 HO. Has a standard 2 row radiator, the a/c fan and a Hayden electric 2 speed fan replacing the engine operated clutch fan(Kicks on at 180 degrees). Motor runs below 210 until I get on the highway. Then it will climb to about 220-230 but doesn't really every seem to want to go into the overheat(RED) area. I have tested the gauge by checking the temp of the head at the temp sender with a temp gun and the temp gun reads 220-230 when the gauge rises. When I stop running at highway speeds or idle around, the temp will go back to 210 or below. There is a 180 degree t-stat in the motor! I am not losing or burning any coolant and the engine seems to be running great. It is a DD and I have experienced no running issue's to date. Has anyone seen this in the past and if so, what was your cause for this? Thanks and Happy Holidays.

 

I'd start by replacing the thermostat and refilling with new coolant. See if that makes a difference. If that doesn't make a difference, look into the water pump or radiator. And verify that your fans are functioning properly

 

I left a few things out there. I have a New t-stat, Water pump, radiator, and upper/lower hoses. Started when the old radiator went bad and then I replaced everything. Has never overheated while I have owned it even when I found the old radiator leaking and replace all the above components. Man this is frustrating.

I do live in South Florida and the temps seem to get up there but the past few weeks its been cool and still seems to ramp up on the temp gauge randomly.

How about a clogged heater core?? Anyone every saw this happen. I was going to bypass and see if that makes a difference.

 

people will tell you there is no need for a fan when driving at highway speed ,i was having the same issue only at high way speeds i would start running hot i replaced my clutch fan and the issue has never returned try hooking one electric fan to run when ever the motors running

 

Has anyone figured this out yet. I have been fighting this for a year now. I live in az and only when outside temps reach over 90 this happens to me. I have new
oem radiator
new water pump
tried 3 different thermostats new
new upper lower hoses
new thermo housing
bypassed heater core
3 different rad caps new
new overflow bottle
electric fan comes on with ignition new
new manual fan clutch and shroud
new head gasket and rebuilt head and bolts
it runs 210 great 50 mph and under, anything over that it climbs up to 3/4 mark but wont ever move to red. Running stock gears with 35s tires but there are plenty of jeeps that run that and don't have this issue. Please somebody help!

 

Have you checked to make sure your temp gauge is working correctly with a laser thermo gun? Ive had to replace my gauge due to it being cracked where it connected to the circuit board (its actually plastic film). Replaced the gauge with one from ebay and now it says it runs 'cool' but the gun doesnt lie!

 

Yeah you should verify your gauge is reading accurately. And consider adding an auxiliary transmission cooler. The AW4 is not a fan of big tires on stock gears. When I added my tranny cooler on mine with 33s and stock gears, it brought the temp down slightly (maybe 5 degrees while at highway speeds). And with larger tires than me, you may see a bigger difference than that

 

Have someone rev the engine and see if the lower rad hose is collapsing. Suction from the water pump can cause it. Some vehicles have a spring installed in that hose to prevent that from happening.

 

is the coolant clean

 

Coolant is very clean. I have done the prestone flush 3 times. Im hoping the gauge is bad but I just figured if a gauge is bad it just wont work at all.