Q: How to replace a thermostat in a cooling system?
A: The first check to make if the cooling system has failed is the coolant level, drive belt tension and temperature gauge operation before blaming the thermostat. Replace with a new one if it seems like a long time for the engine to warm up. To ascertain whether an engine is running hot, try feeling its upper radiator hose with your hand. A scenario where the engine is not very hot but neither is the hose means that usually its thermostat has become stuck; hence, preventing coolant within from escaping into the radiator. Make sure you replace it! However, be advised: Never drive without a thermostat in your car. This may cause the computer to remain in open loop thereby affecting emission and fuel economy. An upper radiator hose that feels hot shows that coolant is flowing and the thermostat is open. For cooling system diagnosis refer to troubleshooting section. Unplug negative battery cable then remove air cleaner; from there follow upper radiator hose to locate thermostat housing on engine; loosen hose clamp and disconnect hose from fitting; unplug electrical connector for engine cooling fan switch; remove bolts and separate housing cover and bracket(if equipped); tap cover with soft-face hammer to jar it loose; note how it's installed and then remove thermostat, clean sealing surfaces thoroughly, put new one in housing, make sure air bleed faces correctly and spring end goes inside towards engine, place gasket over thermostat, put back cover with bolts tightened properly as per recommended torque values of manufacturer at this point reattach pipe into fitting while tightening clamp securely then refill cooling system start up motor and let it reach normal operating temperature so that any leakage may be checked along with proper working of the thermostat.