COOLING SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. Cooling circuit


      1. The 1ND-TV engine mounted on the previous Yaris employs a cooling circuit that bypasses the thermostat, which causes the coolant to flow from the reservoir tank to the engine even while the engine warms up. On the new Yaris, a new cooling circuit has been provided on the 1ND-TV engine to let the coolant pass through the thermostat when it flows from the reservoir tank to the engine. Due to this change, the coolant circulation during engine warm-up will be restricted, as a result, the engine warm-up efficiency will increase, improving the fuel economy.

        A01UW20E02
        Text in Illustration
        *1 Cylinder Block Sub-assembly *2 Radiator Reservoir Tank Assembly
        *3 Thermostat *4 Radiator Assembly
        *a Circulation after warm-up *b Circulation at all times

  2. CONSTRUCTION


    1. Water Pump Assembly


      1. To reduce weight, an aluminum water pump body is used and the volute chamber is integrated with the timing chain or belt cover sub-assembly.

      2. A stainless rotor is used to achieve corrosion resistance and reliability.

        A01UWEQE02
        Text in Illustration
        *1 Water Pump Assembly *2 Timing Chain or Belt Cover Sub-assembly
        *3 Volute Chamber *4 Water Pump Pulley
        *5 Bearing *6 Rotor
        *7 Shaft *8 Water Pump Body
        *a Cross Section - -