The temperature of the engine is regulated by the Mazda thermostat. This is a simple spring activated device that is located at the coolant exit portal near the top of the engine. The manner in which this temperature control device operates is when a certain temperature is reached in the engine, the spring compresses and opens the valves which allow the hot coolant to exit the engine block and be routed to the radiator. This controlling of the temperature in the Mazda engine is the only purpose of the thermostat. The reason a Mazda owner would desire to have a properly functioning thermostat in their engine is so that it can be bought up to operational temperate in an efficient manner when it is closed, and maintain the predetermined optimum operating temperature by opening at the right times. The last advantage of your thermostat is that it will also make it possible for the heater core to receive the correct coolant temperature so the passenger compartment can be properly heated in the cold winter months. The most common malfunction of a Mazda thermostat is when it remains closed no matter what the temperature of the engine is. This prevents any and all flow of coolant out of the engine and into the radiator; causing the engine to overheat. If this occurs to you, the radiator hose can be removed at the housing of this temperature control device and a screwdriver used to force the valve to open. This will make it possible for the owner of the Mazda to drive their vehicle, but do not expect the thermostat to work properly. It will have to be replaced before the spring mechanism in it will have the ability to open and close at the correct temperature again.