mekanic

Ok so my 98 xj has been overheating for a while now off and on. I've replaced the water pump, t-stat, fan clutch and hoses. And she still acts up sometimes. I'm gonna flush the radiator tomoro and if that doesn't fix it then I'll be putting in a new 3 row radiator. Any thoughts on possible problems that I'm overlooking?

ZINGGG

You could need a new radiator cap. Your radiator may be clogged internally. Those are the only 2 components left really. Any record of when the radiator was last changed, if ever? That'd be my guess as to the culprit of your problem

Worst case scenario, you blew a head gasket or cracked your head. How does your oil look?

mekanic

No coolant in oil, so I'll see how she runs after I flush the radiator. After that I'll just put in a new radiator if I have to.

Gee oh Dee

I would think if all cooling parts have been replaced and there is still trouble there is an issue with the HG.

mekanic

Yeah sadly I think I'm gonna have to agree. I just hope the head isnt cracked.

96rokee

couldnt it just be a faulty coolant temperature sensor as well?

just trying to think simple.

someone correct me if im wrong.

and if it is overheating and you cant seem to fix it few solutions ive used would be
180 degree thermo ( instead of oem 195 )
an electric fan override switch
and 1 in hood spacers help quite a bit. ( or hood vents )

ohh and you said over heating,
but you didnt mention how much.? might narrow it down?

ZINGGG

And you also didn't mention if the coolant is boiling over or if you are just going by the gauge that you are overheating. Sensors (like the coolant temp sending unit) have a tendency of going bad in our XJs

mekanic

No boiling over and I honestly didn't think about the gauge going bad. It has a 185 t stat right now and it usually creeps to one tick mark past 210F then straight to 260F.

mekanic

And I'm gonna check on that sensor too. I really appreciate all the input. Thanks.

Radi

I believe 220 deg is the upper limit for "normal". Much above that the PCM slams the temp meter full-right to get your attention.
It'd be tempting to put an actual thermometer of some sort on the thermostat housing to see what it really is.

mekanic

I agree I'm gonna see if my buddy has a temp gun to check it. And I'll probably replace the sensor for good measure

djb383

I kinda doubt the PCM slams the temp needle to the right when temp is north of 220. Under extreme operating conditions, we have momentarily seen 230 on the ScanGauge but the factory temp idiot light never even flickers.

OP, did u replace the radiator?

ZINGGG

OP, you should do this. Besides, the hot time of the year is coming up rather quickly so it's probably necessary either way.

Buy yes, you want to use an infrared gun to make sure your gauge is reading accurately.

Radi

You may want to check the changes Chrysler made to the oil and temp gauges in 1997. Instead of direct reading, they are driven by the PCM.
It was in response to dealer complaints, sick of "warranty" work whenever a customer freaked out over a gauge pointer that moved.

"Algorithms controlling other gauge outputs were designed to provide gauge readings during normal operation that are consistent with customer expectations. Conversely, when abnormal conditions exist, for example, low or high battery voltage, low oil pressure or high coolant temperature, the algorithm drove the pointer to an extreme position."
http://www.allpar.com/trucks/jeep/cherokee-details.html


Ford did them one better, they solved that "moving gauge" problem at one point by running the oil pressure gauge off a switch-type sender. Either it reads normal, or it is at an extreme. One or the other. The PSI numbers are meaningless.

djb383

All good points and I've said numerous times the factory temp gauge is "rigged". At the same time, there have been numerous posts of the factory temp gauge indicating 235. I'm just thinking out loud.