The Pontiac Aztec is powered by 3.4-liter V-6 engine. The thermostat is a key component for keeping the engine running properly. A relatively constant operating temperature is needed to keep the engine performance at an optimal level, which yields good fuel economy and proper emissions. Thermostat problems may include operations of the thermostat or a loss of coolant.
A thermostat is a temperature controlled valve which regulates the flow of coolant between the engine and radiator. The temperature of the engine is controlled by the thermostat by varying coolant flow to the radiator. The thermostat has a spring which expands and contracts with temperature, opening and closing the valve.
The thermostat will block the flow of coolant from the engine while the engine temperature is below the operating temperature of 195-220 degrees Fahrenheit. When the engine is cold, coolant will not circulate, allowing rapid engine warm-up.
As engine temperature rises, the thermostat opens, allowing the coolant to flow to the radiator through the upper radiator hose. The radiator dissipates heat from the coolant, which is then recirculated through the engine via the lower radiator hose and water pump. The pointer of the temperature gauge will move to the center of the dial.
An engine which warms up too slowly and incompletely is an indication of a thermostat which is stuck in the open position. The needle of the temperature gauge may not leave the cold reading [C]. When the engine fails to reach its normal operating temperature, the OBD II [On-Board Diagnostics-Second Generation] will not run in a closed loop. The result of an engine running in an open loop is poor performance and poor emissions, according to Radiator Info.com.
A thermostat which is stuck in the closed position will not allow the coolant to circulate back to radiator. Coolant in the radiator expels the heat it picked up in the water jackets of the cylinder banks. The Pontiac Aztec engine has two water jackets to feed one thermostat. The result is the engine will get hot too quickly and then overheat. The temperature gauge will reach the read area of the dial [H], which will indicate that coolant has overheated. If the condition is neglected, severe engine damage can result, according to Radiator Info.com. Overheated engines can result in damaged head gaskets, according to Troubleshooters.com.
Leaks from the thermostat housing, radiator, heater core or any of the many coolant hoses will result in the loss of coolant. Over time, this will lead to an engine overheating condition. According to Radiator Info.com, coolant leaks are the most common causes of overheating.
