just bought the 89 xj ex chp. has 4 wheel drive and its an auto. but enough about the working parts. any suggestion on why it still overheats? i have replaced the thermostat, water pump, radiator, every single hose, and radiator cap thats on the tank. maybe about 5 minutes into driving the thing (not even reving high or going over 20mph) the temp gauge shoots up like crazy. i shut the car of and nothing happens. no spewing of coolantm or steam. not even an odd hissing sound. im out of ideas here and about to go crazy!!! :dunno: