195 F is OEM (some years 192 F). Stant 14328 or Mopar 4 cyl/I6 spec. Housing on top of head at the front, two bolts.
OEM thermostat for the 4.0L is 195 F (some 1996-2001 list 192 F). Stant 14328 SuperStat is the high-quality aftermarket choice. Lower-temperature thermostats (180 F) reduce overheating margin and cause the ECU to run open-loop longer, hurting MPG; only run a low-temp thermostat in a desert-environment build with verified cooling capacity. Symptoms of stuck-closed: rapid overheating immediately at startup with no airflow to lower hose. Symptoms of stuck-open: takes forever to warm up, heater never gets hot, fuel economy poor. Replacement: drain coolant down a few quarts, remove the two 13mm bolts on the thermostat housing (top of head at front, where upper radiator hose meets engine), pull old thermostat out (note orientation - spring side faces into engine block), clean both surfaces, install new thermostat with new gasket (typically a thin paper or rubber-coated metal gasket), torque housing bolts to 22 ft-lb. Refill and burp the system. The housing itself can crack or warp at the gasket surface - inspect when in there and replace if questionable (Mopar 4694105).
| Part | Vendor | Est. price |
|---|---|---|
| Stant 195 thermostat | RockAuto | ~$12 |
| Thermostat gasket | Fel-Pro | ~$5 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.