I got a 94 Cherokee Country with 209000 miles on it. The jeep never ran hot before I had the head rebuilt and while that was out I put in a new sensor on the back of the head for the gauge as the old one was corroded. With the head rebuilt and new sensor in the gauge will slowly rise up to the red line where the aux fan will kick in and cool it back down. While driving it stays just under the red line and at stops the engine will rise into the red and fan will kick on. I replaced the thermostat, flushed the system, and replaced the fan clutch. I used a laser temp gauge and at the back of the engine sensor the temp is saying 240. At the thermostat housing the gauge is reading 220. The engine can idle all day long out here in the 100 deg days but will not boil over or to a point of extreme overheating. At this point I don't know if maybe the temp gauge sensor is reading inaccurate or if it could be the radiator or water pump.
Also I rebuilt the head due to a sheared off exhaust bolt. Thanks for any input on this.
Douglas

 

NORMAL operating temp is about 210 at the gauge. Suggest trying a 190 deg T-stat. After that Burp the system may have an air bubble trapped in there.

 

Air bubble is a remote possibility. After two or three hot/cold cycles it should have been gone.

Your engine really is running that hot under power. If it did not run hot before replacing the head, then something happened with that head or the installation.

 

Firestorm500 what could have gone wrong that would explain the over temp. I performed checks on the temperature again today the cylinder head all the way around is reading 225 the brass part of the sensor for the gauge is reading 240. Also both hoses upper and lower are running at 170. The old sensor i pulled off was heavily corroded which could have been giving me a false temperature all along.
Douglas

 

What brand/type of head gasket did you use? What about manifold gasket? I assume there's no air bubbles in your coolant res?

 

I used felpro gaskets. And yes I just went ahead and removed the thermostat completely and it still heats up. When the aux fan kicks in at 230 it will cool everything back down.

 

Also I can't feel a spring in the lower radiator hose and both hoses seem weak

 

Some radiator hoses used a spring in them at the original factory build because of the way they put coolant in the new engine at assembly. Lack of a spring does not mean a defect. It may never have had one. A hose without a spring does not collapse during highway driving.

Radiator hoses rot from the inside. Pull the upper one from the radiator when cold and look inside it with a flashlight. If the inside is smooth with no rubber shredding off or cracks on the inside, then you can rule out the hoses for now.

It doesn't sound like the coolant is circulating. Could be either a bad water pump or incorrect installation of the head gasket. A thermostat failing to open can also cause this. But you removed yours and it still overheats.

Remove your radiator cap when cold. Start the engine. With no thermostat, coolant should be moving immediately through the radiator. If it is not, replace the water pump with a Jeep part and FelPro gasket. If it still does not move and/or still overheats, pull the head back off and check how the gasket is installed.

 

Of course, it is also possible that your old, admittedly corroded temp sender was not working properly. [edit: just read that you had considered that] Since it never overheated, it may have been running quite hot for a long time but a defective sender was misleading you. I'm pretty sure the fan is triggered by a separate sensor that threads directly into the radiator but I'm not familiar enough with open systems to say for sure.

The only way your thermostat has anything to do with this (regardless of it's temperature rating) is if it's not opening or only partially opening. I would pull your thermostat and check it by placing it in warm water then raising the temperature of the water. Check it with a candy thermometer or your laser thermometer. Should open fully at rated temp. Don't just dunk it in very hot water, it can damage the thermostat.

 

As stated, his thermostat is out and Jeep still runs hot.

Aux fan comes on at 218 degrees AFAIK.

 

I took out the radiator and water pump the pump looks in good shape but the radiator is definitely old it also had a nest of some kind cover half of the area the mechanical fan flows through. I'm going to replace the radiator water pump and the hoses and hopefully that fixes it otherwise it must be the head gasket at that point.

 

Good plan. I hope that fixes it.

 

Yes on the radiator. Besides nesting animals, the Southwest can be dusty and accumulated dust can cut off airflow to large portions of the radiator causing hot running and overheating.

 

For an update I replaced the radiator, water pump both hoses and so far everything is running good temperature is about 212ish with an outside temp of about 80. Thank you for everyones help it must have just been an old radiator with partially clogged fins.
Douglas

 

I read a lot here on the 195 thermostat, what's the advantage over stock? My 01 creeps a little past 210 occasionally, maybe 2-3 needle widths higher, not to the next mark on the thermo. But, I haven't had it on the beach yet. I have flushed the system and no leaks found.