Sounds like the Thermostat here is the removal and install for your jeep let me know if this fixes the issue if not I will go further into issue
Do not loosen radiator drain cock with system hot and pressurized. Serious burns from coolant can occur. NOTE
Do not waste reusable coolant. If solution is clean, drain coolant into a clean container for reuse. If thermostat is being replaced, be sure that replacement is specified thermostat for vehicle model and engine type.
Drain the coolant from the radiator until the level is below the thermostat housing. WARNING
Constant tension hose clamps are used on most cooling system hoses. When removing or installing, use only tools designed for servicing this type of clamp, such as special clamp tool (number 6094). Snap on clamp tool (Number HPC-20) may be used for larger clamps. Always wear safety glasses when servicing constant tension clamps. CAUTION
A number or letter is stamped into the tongue of constant tension clamps. If replacement is necessary, use only an original equipment clamp with matching number or letter.
Remove radiator upper hose and heater hose at thermostat housing.
Disconnect wiring connector at engine coolant temperature sensor.
Remove thermostat housing mounting bolts, thermostat housing, gasket and thermostat. Discard old gasket.
Clean the gasket mating surfaces.
Install the replacement thermostat so that the pellet, which is encircled by a coil spring, faces the engine. All thermostats are marked on the outer flange to indicate the proper installed position.
Observe the recess groove in the engine cylinder head.
Position thermostat in groove with arrow and air bleed hole on outer flange pointing up.
Install replacement gasket and thermostat housing. CAUTION
Tightening the thermostat housing unevenly or with the thermostat out of its recess, may result in a cracked housing.
Tighten the housing bolts to 16 ft. Lbs.(22 Nm).
Install hoses to thermostat housing.
Install electrical connector to coolant temperature sensor.
Be sure that the radiator drain cock is tightly closed. Fill the cooling system to the correct level with the required coolant mixture.
Start and warm the engine and check for leaks.
Wednesday, January 28th, 2009 AT 9:06 PM