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.

 

Your action plan is good so far but you might consider a fan clutch from a GC to replace it.


A partly stuck thermostat could cause that problem and is older from what you say. I replace mine at least every 2 yrs when I clean/flush/replace anti-freeze most are junk anymore.

 

What Fred said.
I would not do #4.

 

It's just leting the torque converter slip and heat up.
Happens all the time on the trails when crawling. Was just simulating that senario.

 

I'm doing the Grand Cherokee clutch fan in mine. I'm also going to run the CSF 2-row all-metal radiator. I think these upgrades could benefit you too.

Here are some links for you:

CSF 2-row brass all-metal radiator P/N 2670:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

NAPA ZJ clutch fan P/N 272310:

http://www.napaonline.com/Catalog/Ca...310_0361914528

 

Well I picked up a new 195 T-Stat & 13PSI Cap. I'll put them on tonight and do another test.

As for the Fan, I think the ZJ Clutch Upgrade is a good move to make.
However, for me a better move would be to install the 2-Speed Ford Taurus fan I've had in my shop for 5 years...
So I'll be ordering parts to finish that swap if fix number one doesn't work.

 

Another possibility is that the transmission is dumping excessive heat into radiator heat exchanger.
A slipping torque converter quickly creates high temps.
Test #7 is a symptom of not enough airflow.

 

When you go to NAPA to get your clutch fan order by the part #272310. It's not a ZJ item(272306 or 272314)


272310:
JeepCherokee2.5 L 150 CID L4 AMC Design1994 - 2000
JeepTJ4.0 L 242 CID L61997 - 1999
JeepWrangler4.0 L 242 CID L61991 - 1995
JeepWrangler4.0 L 242 CID L61997 - 1999
JeepYJ4.0 L 242 CID L61991 - 1995

 

That's why I did test number #4.

I agree that I think the problem is from poor air flow.
I should have plenty off cooling capacity since I'm running through the heater core all the time.

I either have to turn on the heat Fan or the AUX fan to cool it back down.
In my mind this is pointing towards needing more CFMs so likely my clutch is worn out on the Mechanical Fan.

Going to the J/Y tomorrow to pull some parts I need to finish my E-Fan. 4500 CFMs....

 

I had a problem like this last summer. I removed my auto trans line from the radiator and ran it to an external cooler has been fine ever since. The trans does dump a ton of heat into the radiator. Before I did this I spiked my temp gauge to 240 and could not open the hood because it was too hot to touch. I am also running a 98 TJ fan clutch on mine. The TJ clutch in only .125" longer than the stock XJ. It will no sit too far into the fan shroud and create a suction problem. The relationship between the fan and the shroud is important to maintain proper airflow. The ZJ clutch is .25" or more longer then the stock XJ.

 

Have you read the reviews on that radiator and problems with leaking they have. I personally do not have one have read posts here and on NAXJA from numerous people who bought them and they leaked in short order. The said they returned them and got another one just to have the same issue. Seems like most ended up selling them, this is just from what I have read and you know its the internet.

 

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 tightended 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.

 

Hope that was the cure it very well could be and the cheapest of the fix's.

 

Since I have put a winch on and power steering cooler, air flow seems to have made mine have some issues. I also found that my auxiliary fan wasn't working at all. The rely was out. but I decided the best course of action would be to be able to override the auxiliary fan. Here is a write up on how this guy did his. http://www.cherokeetalk.com/forum/f6...verride-13929/