A few weeks ago my wife woke up to her 98 cherokee classic 4.0 with a puddle of radiator fluid underneath. She didn't run it low on fluid judging by the puddle and the ammount still in the radiator it was just a slow leak that finally split the hose. I replaced the hose and while i was at it I flushed the radiator. I saw that the radiator fluid was the orange fluid like you see in a GM vehicle and replaced it with the same. It ran fine for about a week and then she called me and told me that her jeep had overheated (check gauges light, temp was at 250) so she pulled over a few minutes to let it cool down. she has a long commute so I let her drive my truck from then on and I've been driving the jeep and just nervously watching the guage. Well today coming down the highway, watching the gauge every 45 seconds or so because the temp out side was 100, and I had the A/C on full blast so I was keeping a close eye. Well all of a sudden the check gauges light came on and the temp instantly went from 210 to 250. I instantly cut the heater on full blast and looked for a place to pull over. not 15 seconds later the light went off and the temp went back to 210 like nothing ever happened. Should I send it to a mechanic? does anyone know whats wrong? maybe a bad temp sensor or gauge?

EDIT sorry should have realized this was the grand cherokee forum, my mistake

 

first replace with green rad fluid. a good 50/50 mix or maybe a 60/40(water/antifreeze).

check rad cap for proper PSI. check thremo stat (or replace because its like $5 and $0.99 for the gasket).



but if it is jumping the much on an instant it sounds like a bubble in the system.


open the rad cap, run the heater on full blast with the engine running and add fluid as needed thru the fill neck.


then for the next week watch the overflow bottle for fluid level.


also if you only replaced that one hose i would replace the others as well.

 

i would also replace with proper green antifreeze and change the thermostat and gasket never hurts esp. when vehicle got hot. the temp gauge is kinda rare that I know of for just jumping like that usually it kinda creeps up, dont have a answer for that one hopefully not a head gasket.