Jeep coolant temperature help

tsubaki · #1 10-08-2012, 09:56 AM

I'd really appreciate some input on a 1996 Cherokee Classic 4WD with automatic transmission, AC and 4.0HO engine.
About mid summer I kept noticing the temperature gauge seemed to be reading a little higher than the normal 210 degrees while driving around town for brief 15 minute trips. But after about 30 minutes of intown or interstate driving the temperature would climb to about 230 degrees. Running with the AC on or off seemed to make no difference.

While sitting in the yard with the engine at 2000rpms, I can make the electric fan come on at about 235 degrees. As it also does when the AC is on.
I'm still having this problem with daytime high temperatures of 80 degrees and less. And there is no evidence of coolant contamination.

Here's a list of things replaced so far.
180 degree thermostat
Radiator
Catalytic converter, muffler and tail pipe
Fan clutch
Water pump
Temperature sending unit

Any ideas???

spareparts · #2 10-08-2012, 09:57 AM

have you actually put a thermometer or a heat gun on it to see if the temp is accurate?

tsubaki · #3 10-08-2012, 10:01 AM

No I haven't spare thanks, I might as well get one and see.
I figured since the electric fan comes on so close to the gauge reading it might be close.

jasoncooperpcola · #4 10-08-2012, 10:07 AM

Maybe you need to go to a lower temp thermostat?

tsubaki · #5 10-08-2012, 10:17 AM

It had a 195 degree in it for at least 2 years before the overheating indication and it stayed around 210 degrees.
Got the same vehicle but a year newer with a 180 thermostat and it stays at about 210.

Destroyer · #6 10-08-2012, 11:09 AM

Pull a compression test on your cylinders. These engines are just about bulletproof, but I've seen several of them with bad head gaskets. I had just about the same problem on my 98 Jeep Cherokee Sport. Turned out to be a bad head gasket between number 2 and number 3 cylinders. Fairly easy to replace, just a PITA.

THEFERMANATOR · #7 10-08-2012, 11:26 AM

Quote:

Originally Posted by jasoncooperpcola

Maybe you need to go to a lower temp thermostat?

Lower temp t-stats NEVER stop overheating, it ONLY makes it take longer to overheat.

tsubaki · #8 10-08-2012, 05:02 PM

Thanks FERM, the sensor I replaced is the one at the rear drivers side that disabled the temperature gauge when disconnected. The one at the thermostat housing initiated the electric fan and set off the check engine light when disconnected.
New radiator and no build up in the old one, replaced it anyway. The condenser does have a few flat fins and a fair amount of gravel lodged in it but I can see through a very high percentage of it to the radiator.
This animal has never lost coolant or gave any of the normal overheat indications except for the gauge.
I'm aware of the air blockage especially on the ones that have the funny looking tank. This one has the regular old overflow type.
My next thought was to replace the condenser, basically because of the elimination process order I've replaced prior. Then pull the head and replace the gasket if that don't help.
First I'm gonna do like spare suggested and see if I can determine if the gauge is close to correct.
Keep throwing this stuff this way please!