Before assuming the thermostat is to blame for a cooling system problem, check the coolant level, drive belt tension, and temperature gauge operation. If the engine takes a long time to warm up, replace the thermostat. Replace the thermostat if the engine runs hot and the lower radiator hose is not hot. Do not drive without a thermostat as it may affect the engine's performance, emissions, and fuel economy. When replacing the thermostat, disconnect the battery cable, drain the cooling system, locate the thermostat housing, detach the hose, and remove the housing cover. Note the air bleed valve position and fit a new gasket over the thermostat. Install the new thermostat correctly, reattach the cover and bolts, securely reconnect the hose, and refill the cooling system. Start the engine and check for leaks and proper thermostat operation.