Just recently I purchased a Jeep xj cherokee, 95, 4L S6 with 107k.
When test driving the vehicle I never saw any issues with the temp gauge, nor did the previous owner say anything about it.
A week after having it, while on the highway with the AC on i noticed that the temp gauge began to climb to around 250 before i pulled over.
Then a day or two after while driving on the highway with no AC on it did the same thing. even driving at 50mph it maintained its temp at 250.
There were no problems with the temp when reaching sustained speeds at 45 or 50. Until I brought the car to stop and idle, which then caused the temp to increase.
I couldn't identify any problems with the water pump, or the coolant itself. I thought I would just flush the system all together and start fresh. I have not done this yet and for the past week, while driving on the highway and idling there have not been any temp problems what so ever.
Could this be a bad Thermostat?
I also see a trend in the weather, where last week it was 90< every day, and this week it is 80s.
Could it be a gunked thermostat? or could weather just be the problem with everything?
I had the same problem with mine. Changed the radiator, no change, changed the fan clutch no change, replaced the electric fan relay in the fuze panel box by the battery no change, fuze for the electric fan in the fuse panel by the battery was bad so I replaced that and it helped it a little. Pulled the thermostat and it was broken in half, changed that and my 95 jeep cherokee never gets above 205 even in traffic with the ac on high and the temp is 100 degrees. I should have went in reverse order of replacing all those parts and it would have been cheaper but I know I will not have to change those things for awhile. Change your fluid also, it can't hurt. I also have a straight 6 and stock radiator.