If you drained the radiator fluid from the radiator in your 4.0-liter Jeep Cherokee so you could replace the radiator or thermostat, when you place the fluid back into the radiator you must purge the air trapped inside the radiator coolant system. If you allow air to remain in the coolant system, your engine will experience erratic heating and cooling that could result in your engine overheating.
Remove the radiator cap from the top of the radiator.
Start the engine of your Jeep Cherokee and allow it to idle. Run the engine until the radiator fan turns on, runs a complete cycle and turns back off.
Turn off the engine and top off the radiator by placing more coolant into the filler spout.
Turn the engine on again and allow it to idle. Wait for the fan to turn on and turn off again. Turn off the engine and place the radiator cap back onto the radiator.
