My girlfriend just got her wrangler its a 2002 tj 4 banger auto. anyway we were driving yesterday for a little bit when it suddenly started getting really hot. It did this the other day too we had to let it cool down before we drove it home. It has plenty of coolant, and the radiator looks fine. The other day when it got really hot and then we turned it off we could hear something boiling like the radiator fluid or something. any clue what this problem could be? I was thinking it could be the thermostat is just not working correctly so it wouldn't release coolant into the engine when it got hot? how do you tell if it is the thermostat? what else could it be?
what color is the coolant? is there any brown mud in the overflow container? if so, its likely your coolant's pH is f'ed causing some rust inside the block, heater, etc and could be causing a clog in the system. you'll need to flush the fluid system completely with garden hose, then install new coolant. if you need to replace the thermostat anyway, this is the perfect time to flush the whole system.