Questions and Answers

Jeep Cherokee Sport Overheating Q. Hi Vincent, Your web site is a breath of fresh air. Hope you can help me with this issue, its driving me crazy. 1993 Jeep Cherokee Sport 4.0 liter 4WD Automatic transmission 88,000 miles Fuel Injection P/S, A/C

It was last summer, I live on Long Island, when I noticed the cooling temperature rising over 210° only when I stop for a light or stop sign, i.e. idling after running at 30 mph or greater. Once I am back to higher speed it cools back down to 210°. On a real hot day, 90° or better, it may get to 230° but again when I start moving it cools down to 210°.

I have flushed the system, changed the thermostat, water pump, upper radiator hose and checked to see the coolant levels in both the radiator and the overflow bottle are where they should be. Also, the aux electric fan does come on when the temp goes above 210°.

I get plenty of heat in the winter and the coolant temp does not go beyond 210° so I believe the heater core is okay. The following have been suggested to me but I'm not sure if I should spend the time and money without running some tests. A new overflow bottle, radiator or new fan clutch.

I should note the overflow bottle has a crack in it above the coolant level and has leaked some coolant in the past if the level gets to the level of the crack. I'm not sure if the bottle is pressurized and thus relieving system pressure. Would greatly appreciate your expertise in resolving this problem.

I will follow your instructions. I am getting nervous with spring approaching since I know I have to fix the problem real soon. Otherwise, she runs great and I really like the truck.

Thanks very much for your time,
Bob

A. I was born and raised on Long Island. I lived there until 1978 when I moved to New Jersey.

It could be a bad fan clutch. To check the clutch fan, disconnect the bi-metal spring and rotate it 90° counterclockwise. This disables the temperature-controlled, free-wheeling feature and the clutch performs like a conventional fan. If this cures the overheating condition, replace the clutch fan.

The cracked coolant reserve tank is not pressurized and will not cause an overheating condition. I would, however, suggest going to the local junk yard and picking up a used tank and put it in.