01 XJ Not Reaching Operating Temp

[JMA_2001XJ]

First off, I just recently picked up a 01 XJ 4.0 with 93k, very clean. This is my third one, I have had a 1989 and a 1999. It has some issues that I am chasing down but nothing crazy. What I am working on now is that it is not reaching operating temp. Typically it gets to about 165ish. I am in NY and it is cold but not that bad, in the 30's-40's. The heat was not really working that well so I flushed the heater core, bled the system and it definitely made a difference, especially at idle, while driving it is warmer then it was but not crazy warm by any means. A lot of rust came out when I did the flush. The thermostat was just changed twice and the water pump was recently replaced as well. I was thinking that the fan was just blowing all the time and the clutch was frozen so it could not get to temp. But I went to check it today after a drive and it just spun freely after I turned the jeep off, it does not stop. So I know that the clutch fan is bad, but can it spin all the time when the engine is running all the time if it is not frozen? Thanks in advance.

 

[Tim_MN]

195* thermostat ? Genuine Jeep or Stant thermostat, and not Chinese crap in store brand boxes ? My 2000 runs at 195* even at 15* below zero. A failed thermostat showed random temp fluctuation and low operating temps.

Rust in the system means neglected maintenance.

Most auto parts stores sell cheap crappy Chinese made parts, some that even come with a "Lifetime Warranty". These parts are poorly manufactured and/or made from inferior materials. They are often out of specification, or even failed, right out of the box. The ones that are not faulty many times will have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep engine sensors. Numerous threads detail long and frustrating searches for a "problem" that ended up being cured simply with genuine Jeep repair parts.

Cheap parts are cheap for a reason.

 

[JMA_2001XJ]

It is a Stant thermostat. Any thoughts on the fan?

 

[Unclewolverine]

If you have changed the stat twice and it is a good stant stat I would venture to guess that the sensor or gauge isn't working right.

 

[maxbraketorque]

Hard to imagine an XJ unable to reach operating temperature. I second the suggestion to check the sensor and gauge. An OBDII reader will tell you if the gauge is off. Need to put in another sensor to check sensor.

 

[techno1154]

Even in Florida with a really clean cooling system and electric fans that are set to run above 210* my XJ temperature remain below 185* on the highway with a cheap 185 T-stat that opens fully below 185. I replaced it with one from the jeep dealer. Now it runs at 200 +/- all day at highway speeds.

Check the T-stat again. It is easy and cheap to do using a thermometer that one uses to check turkey and a pot of water on the stove. I think the OEM T-stat begin to open at 195 and fully open about 10 degrees higher.

 

[JMA_2001XJ]

If you have changed the stat twice and it is a good stant stat I would venture to guess that the sensor or gauge isn't working right.

Are you talking about the sensor in the thermostat housing? That was recently changed prior to my purchase of the vehicle.

Any thoughts on my fan clutch inquiry?

 

[Unclewolverine]

That is the only temp sensor on an 01. The fan clutch is a non issue. Fully locked, and the aux fan on it should still come to temp. Also, just to mention 00-01s are known for having numerous electrical problems including bad gauge readings. Get a mechanical read on the temp.

 

[JMA_2001XJ]

That is the only temp sensor on an 01. The fan clutch is a non issue. Fully locked, and the aux fan on it should still come to temp. Also, just to mention 00-01s are known for having numerous electrical problems including bad gauge readings. Get a mechanical read on the temp.

OK, thanks. But if the fan spins freely and does not stop after shutting the jeep off it is bad and should be replaced, correct??

 

[Tim_MN]

195* thermostat for OBD-II ?

Any faulty or suspect cooling system parts should be replaced. The 2000-01 have the 0331 head casting which prone to cracking caused by abuse from overheating.

The Coolant Temperature Sensor is a cheap and an easy swap. Use genuine Jeep parts. It also can be tested.

 

[Unclewolverine]

OK, thanks. But if the fan spins freely and does not stop after shutting the jeep off it is bad and should be replaced, correct??

Can't diagnose that one until you can come up on temp. It should basically freewheel when cold and only start locking up when the engine is warm, like really warm. I rarely hear mine start ro kick in until the ambient is in the 90s and I've been stop and go for a while.

 

[JMA_2001XJ]

Can't diagnose that one until you can come up on temp. It should basically freewheel when cold and only start locking up when the engine is warm, like really warm. I rarely hear mine start ro kick in until the ambient is in the 90s and I've been stop and go for a while.

Is is supposed to spin when you first turn the jeep on?

 

[techno1154]

Is is supposed to spin when you first turn the jeep on?

It does spin up fast on first start up to move the oil around then slow down until the engine is fully warmed up during which time it tends to freewheel.

However, a bad fan would cause an overheat not over cool. Your problem could be electrical in that there is a problem between the sensor and the gauge or the thermostat itself is bad.

 

[90xj06]

in the winter driving i fluctuate around 160-170. if i leave it idling for some time it might get up to 180-190 but the second you start moving it drops right back down. i think the stock thermostat is 160 so at minimum once warmed up it should not drop below this.

this is on an 88. so i'm reading the ecu water temperature. the dash gauge only really gets to the tick between 100 and 210.

 

[JMA_2001XJ]

I just changed the thermostat to a Mopar part (although the one that was just took out and replaced was a 195 Motorad part) and still not getting to temp and no real heat.

 

[techno1154]

I just changed the thermostat to a Mopar part (although the one that was just took out and replaced was a 195 Motorad part) and still not getting to temp and no real heat.

It is time to begin looking deeper into what keep the engine temperature low. Inspection of the thermostat housing is in order including the area on the head especially where the thermostat sits.
Are the hoses off the thermostat housing and the return from heater core connected properly? (I don't see how that could get messed up).
If you were to just sit and let the engine run (not moving) for 30 minutes will the temperature, get to 195+?
What is the history of your XJ regarding the cooling system?

My XJ have no mechanical fans for almost 20 years. In 2007 I worked in Iowa. During the winter there My XJ would not get to thermostat temperature at highway speeds, but it would when sitting with the engine running. My solution? Cover half the radiator with cardboard. This is not ideal, but it get the job done.
I say all this to say there is something we do not know or maybe like me in Iowa winter, it is just too cold for when the second radiator (the cabin heater) it put into the mix.

 

[RCP Phx]

Have you done a compression test and better yet a leak down test?

 

[Tim_MN]

Confirm the the dashboard temperature dispaly with an IR temperature gun pointed at the thermostat housing.

Is the coolant mix 50%-50%.

A failed mechanical fan could potentially cause over-cooling.

 

[JMA_2001XJ]

I flushed the heater core again and used CLR this time. More rust particles came out and the heat is way better now. Actually warm in this fridged NY weather.