Description

DESCRIPTION

The cooling system is sealed and of the forced circulation type. It features a centrifuge pump (1) operated by the crankshaft by the timing belt. A thermostat valve (2) located on the rear of the engine ensures optimal engine temperature. It opens when the coolant reaches a temperature of 83°C. The radiator (3) cools the fluid by means of dynamic air and a fan. The fan is controlled by the injection-ignition ECU according to a specific logic (for greater details see ELECTRIC-ELECTRONIC DIAGNOSTICS - Section 26 for versions with climate control and Section 27 for versions with heater). The expansion reservoir (7) feeds the circuit if the level decreases and absorbs the fluid variations in volume according to the temperature. Furthermore, it acts as a circuit air bleeder. A double NTC thermistor coolant temperature sensor is fitted on the thermostat cup. One NTC thermistor sends a signal to the injection ECU while the other sends a signal to the instrument panel temperature gauge and warning light.

CIRCUIT OPERATION

The fluid cools the engine a reaches the thermostat (2) via the cylinder head. If its temperature is lower than 83 °C, the coolant is sucked by the pump (1) via a longitudinal return manifold (11) located on the left-hand side of the cylinder head. If the temperature is higher than this value, the coolant is conveyed to the radiator (4) via the thermostat opening. After being cooled in the radiator, the coolant returned to the thermostat from where it is conveyed to the pump via the longitudinal manifold. Furthermore, from the thermostat cup the coolant is conveyed to:

• the expansion reservoir also for bleeding the circuit;
• the climate control system to return to the longitudinal manifold;
• heat exchanger (12) for cooling engine oil. It is then let out and directly conveyed via the coolant return longitudinal manifold to the pump.

The expansion reservoir feeds the engine cooling circuit via a specific connection pipe on the longitudinal manifold.