GM 94840247 Housing,Engine Coolant Thermostat Lower

Before assuming the thermostat is to blame for a cooling system problem, check coolant level, drivebelt tension and temperature gauge (or light) operation. If the engine takes a long time to warm up, the thermostat is probably stuck open. In this case, replace the thermostat. If the engine runs hot, use your hand to check the temperature of the upper radiator hose. If the hose is not hot, but the engine is, the thermostat is probably stuck in the closed position, preventing the coolant inside the engine from escaping to the radiator. Again, replace the thermostat. If the upper radiator hose is hot, it means that the coolant is flowing and the thermostat is open. To replace the thermostat, disconnect the negative battery cable, drain the cooling system, and remove the upper radiator hose from the thermostat housing. Remove the bolts from the thermostat housing and detach the housing. Be prepared for some coolant to spill as the gasket seal is broken. Remove the thermostat, noting the way it was installed. Remove all traces of gasket material from the sealing surfaces. Apply gasket sealer to both sides of a new gasket and position it on the engine. Install the thermostat (spring end first), housing and bolts. Tighten the bolts to the specified torque. Finally, refill the cooling system.