Runnig

Had some issue on the trail yesterday with the Jeep wanting to run 220-230 on the trail. Even on the ride home it was running between 210-220. About 90 degrees outside. I had to turn the heat on with the fan blowing across the heater core to keep it at 210.

So heres what I've got:

Factory Radiator
Factory Radiator Cap
Factory Catch Tank
Factory Fan Clutch
Water Pump replaced OEM 2009
T-Stat Replaced 195 in 2009
Radiator Fuild is Full
Fluid is fresh and good color green
I have my heater control valve bypassed so fluid always runs through the core


Did some testing today:

1) Cold start crank, let idle for 20min warmed up slowly to 200 and stayed there.

2) Turned on A/C, 5min Aux fan turned on, stayed at 200.

3) Turned off A/C, Aux fan turned off still 200

4) Set Ebrake, placed in Reverse, applied brake, reved to 1250 for 10min.
Warmed up to 220 Aux fan turned on.

5) Aux fan Cooled down to 210 turned off

6) Placed Jeep in park

7) Jeep slowly heats up to 220 over 10min

8) Aux fan turns on, jeep cools to 210

9) Jeep Repeated 7 - 8 three more times turned off jeep


Notes: When the Jeep is cool the tank is at the full mark.
Warmed up at 210/220 it's 3/4" above full line.
When's the Aux fan turned on at 220 the fluid dropped a .25" below that point, .5" above full line. ( I made marks on the tank to record this)

Radiator fins, trans cooler, and condenser are all straight and cleaned.
I washed them again today before this check to be sure.

Thoughts???


My current action plan, replace Radiator Cap & T-Stat (195) becuase there cheap. However judging by my test results I'd say neither of those is malfunctioning. Also considering the fan clutch as a swap as well.

After performing test I turned off the jeep and flicked the fan with my finger it spends about .25 turn then stops. Appears to have good resistantants.

Changed the t-stat & cap.

When I started it up the belt was making a faint squeal, from the antifreeze that spilled on it. I tightened it up a few turns and it stopped.

Repeated all my test and she stayed at a constant 210.

Need to test drive to confirm but she past the driveway idle.

220*-230* isn't actually overheating, but is almost there. Overheating on 4x4 trails, and in heavy traffic is typically a weak or failed mechanical fan clutch. I would install a fresh fan clutch if it was my XJ.