Jeep 4666140AA Thermostat

Before assuming the thermostat is to blame for a cooling system problem, check the coolant level and temperature gauge operation. If the engine seems slow to warm up, the thermostat might be stuck open and needs replacement. If the engine runs hot and the upper radiator hose isn't hot, the thermostat could be stuck closed and must be replaced. Caution: Don't drive the vehicle without a thermostat as emissions and fuel economy may suffer. If the hose is hot, it indicates the coolant is flowing, and other cooling system diagnosis may be required. To replace the thermostat, disconnect the cable from the negative battery terminal, drain the cooling system, and locate the thermostat housing cover by following the upper radiator hose. Loosen the hose clamp, detach the hose, and remove the housing cover fasteners and cover. Take note of the thermostat and gasket installation, remove material from the staked areas if necessary, and clean all traces of the old gasket from the surfaces. Install the new thermostat with the jiggle pin at the 12 o'clock position, and the spring end directed into the engine. Use RTV sealant if appropriate, and install a new gasket. Reattach the cover, hose, and all previously removed components, reconnect the battery, refill the cooling system, and start the engine to check for leaks and proper thermostat operation.

To replace the thermostat in a vehicle, begin by disconnecting the negative battery cable. For a secondary thermostat, remove the air filter and intake hose assembly, coolant hose, electrical connector, and radiator hoses. Clean the surfaces, install a new gasket/O-ring, and install the parts in reverse order.

Before assuming the thermostat is to blame for a cooling system problem, check the coolant level and temperature gauge operation. If the engine seems slow to warm up, the thermostat might be stuck open and needs replacement. If the engine runs hot and the upper radiator hose isn't hot, the thermostat could be stuck closed and must be replaced. Caution: Don't drive the vehicle without a thermostat as emissions and fuel economy may suffer. If the hose is hot, it indicates the coolant is flowing, and other cooling system diagnosis may be required. To replace the thermostat, disconnect the cable from the negative battery terminal, drain the cooling system, and locate the thermostat housing cover by following the upper radiator hose. Loosen the hose clamp, detach the hose, and remove the housing cover fasteners and cover. Take note of the thermostat and gasket installation, remove material from the staked areas if necessary, and clean all traces of the old gasket from the surfaces. Install the new thermostat with the jiggle pin at the 12 o'clock position, and the spring end directed into the engine. Use RTV sealant if appropriate, and install a new gasket. Reattach the cover, hose, and all previously removed components, reconnect the battery, refill the cooling system, and start the engine to check for leaks and proper thermostat operation.

To replace the thermostat in a vehicle, begin by disconnecting the negative battery cable. For a secondary thermostat, remove the air filter and intake hose assembly, coolant hose, electrical connector, and radiator hoses. Clean the surfaces, install a new gasket/O-ring, and install the parts in reverse order.

Check the coolant level, drive belt tension, and temperature gauge. Disconnect the negative battery cable and drain the cooling system. Locate the thermostat housing and detach the hose and remove the housing cover. Install the new thermostat and gasket.

Before assuming the thermostat is to blame for a cooling system problem, check the coolant level, drive belt tension, and temperature gauge operation. For 4.0L engines, disconnect the cable from the negative battery terminal and drain the cooling system. Remove the air filter housing and upper intake manifold, then remove the thermostat housing bolts and housing from the lower intake manifold.

Before replacing the thermostat, check the coolant level, drive belt tension, and temperature gauge. Disconnect the battery cable and drain the cooling system. Follow the upper radiator hose to the engine to locate the thermostat housing. Remove the bolts and detach the housing cover. Note how the thermostat is installed and remove it. Clean the housing and cover, then install the new thermostat. Install the cover and bolts, then reattach the hose and tighten the clamp.