Cooling System - Operation

GAS ENGINE

The primary purpose of a cooling system is to maintain engine temperature in a range that will provide satisfactory engine performance and emission levels under all expected driving conditions. It also provides hot water (coolant) for heater performance and cooling for automatic transmission oil. It does this by transferring heat from engine metal to coolant, moving this heated coolant to the radiator, and then transferring this heat to the ambient air.

- When the engine is cold and both the primary and secondary thermostats are closed. The coolant will circulate through the engine, heater system, and the bypass. The cooling system has no flow through the radiator
- As the engine warms up, the primary thermostat will start to open at 77 °C (170 °F). Coolant will start to flow through the radiator and the internal transmission cooler. The primary thermostat will fully open at 95 °C (203 °F).
- The secondary thermostat will start to open at 95 °C (203 °F). This will increase the coolant flow through the cylinder block and cylinder head and the radiator. The secondary thermostat will fully open at 104 °C (220 °F).
- TURBOCHARGED ENGINE ONLY:the turbocharged engine has a single thermostat that starts to open at 90.5 °C (195 °F) and is fully open at 100 °C (212 °F). This is done to reduce resistance and increase flow.