Pic. 2.19. Scheme of the 2AZ-FE engine cooling system: 1 – oil cooler with water cooling; 2 - coolant pump; 3 - throttle branch pipe; 4 - bypass channel; 5 - thermostat; 6 - drain cock
The cooling system is closed with forced circulation. A thermostat with a bypass valve is located on the body of the cooling system inlet to maintain an appropriate temperature distribution in the cooling system. This prevents sudden temperature spikes when the engine warms up. The coolant flow makes a 180°turn in the engine block to ensure smooth coolant flow. In addition, a bypass channel is located in the cylinder head and cylinder block. The heated fluid from the engine flows to the throttle pipe to prevent it from freezing. A water-cooled oil cooler was installed between the crankcase and oil filter on 2AZ-FE engines.
Pic. 2.20. Schematic diagram of the 2AZ-FE engine cooling system: 1 - thermostat; 2 - coolant pump; 3 - throttle branch pipe; 4 - expansion tank; 5 - drain valve; 6 - bypass channel; 7 - coolant pump; 8 - oil cooler