OEM 195* thermostat is the best replacement. It should have one mechanical fan and one electric fan unless someone has changed it to two electric fans. If it does have a mechanical fan the fan clutch may be weak causing the rise in temps at slow speeds or idle. Be careful with overheating the 00 model as the head casting for that year is flawed and prone to cracking very easily. Just do a search on 0331 head casting and you will see.

 

Thanks. I am aware of the 2000 heads, but regardless, I don't want anything overheating. It probably is just the thermostat. I'll do a flush and replace it as a "thank you" for letting me borrow it the other day.

 

Could be the fan clutch failing as well. Only one fan is electric.
Is the coolant level where it should be?

 

I didn't watch the fan(s) for any long period of time, but I did see both on or cycling on/off parked.

The coolant level was fine, although I'm sure it is very old and probably original. I'll be replacing that when I do the thermostat.

 

This is my parent's Cherokee that I was recently borrowing for the day, it is a 2000 with 85,000 miles.

It was a warm but not hot day. I noticed it was running around 150 degrees or so around town, but when idling waiting parked for any more than 4 minutes, I noticed the temp start skyrocketing to 240 or so. As soon as I would start moving, the temp dropped back down to well below normal.

over cooling is a sign of a stuck open t-stat (i.e. 150 degrees). the super high temp (i.e. anything over 210/215) at a light or in slow traffic might be a sign of either the electric fan not kicking on or the clutch fan not working correctly.

me personally have never herd of a car under and over cooling at the same time usually one or the other.

 

Mine did both recently.

I had a radiator leaking at the tank so I put in a new OEM spec one plus a new 195 deg T stat and a 15lb (or whatever it is you guys say to use) cap.

It ran too cool. I drove it to Traverse City MI 600 miles on a 95 deg day. It ram 160 deg and even dropped to 100. I assumed a stuck open T stat. I swapped in another on and had the same results. I have the OE gauge and an aftermarket gauge. When I shut off the engine the aftermarket gauge would leap to 140 degrees and gradually cool. The Jeep ran 150deg all day long.

As an experiment I put in the factory T stat that had run it at 212 deg for a year or so It now ran 212 unless I stopped. Then it started hitting 225-240 until I drove off.

The last time I drove it it hit 250 0n the aftermarket gauge and 220 on the OEM one. It ended up boiling all the coolant out.

At this point I am replacing everything I can to see if I can fix the issue.
With the AutoZone/NAPA Tstats I did have too cool and too hot issues.

 

Just because the mechanical fam is turning doesn't mean it is working correctly. The fan clutch allows it to slip a certain amount when it doesn't need the extra airflow and tightens up as the temperature rises making it pull more air through the radiator. If the clutch is worn/weak it will not pull enough air to cool it at idle or slow speeds.

 

ya for the clutch fan if its cool with the car off you should be able to spin it without resistance but it should stop right after you let go if it continues to freewheel its bad

and if the cars hot with the engine off you shoud not be able to turn the fan or if you can it should be fairly hard to do.

 

At a guess ...

Stuck open or missing thermostat,

and ....

Failing FanClutch.

Might want to also check that the connection at the Coolant Temp Sensor is good/clean ... altho the flip flop temps that can cause ... would normally be evident at all speeds.

 

I checked the fan and the clutch seemed good. I then went ahead and changed what looked like the original, 2000 79k mile coolant and thermostat. The overflow tank was nasty with crud, although the coolant in the radiator looked good.

Anyway, after a good flush, a new thermostat and gasket, the Jeep is back on the road and appears to hold a stable temp around 200 whether it is idling or driving along.

 

when i bought my 96 from my brother in law 2 weeks ago, he told me that the thermostat would need replaced, but i haven't noticed any high temps while driving around.

 

This Jeep ran cool around town and hot when in traffic or at a red light. $20 for the part and gasket, and $30 for much needed coolant. A nice cheap fix.

 

I had an exploder that would only run hot if over 65 mph.
The Tstat was stuck part way open. It would open and cool fine unless you were at high speeds.
We only noticed it when on the interstate.

Glad you got it fixed.