Description

DESCRIPTION

The cooling system is sealed and of the forced circulation type. It features a centrifuge pump (1) operated by the crankshaft by means of a Poly-V belt.

A thermostat valve (5) located on the rear of the engine ensures optimal engine temperature. It opens when the coolant reaches a temperature of 87 ± 2 °C.

The radiator (4) cools the fluid by means of dynamic air and a two speed fan. The fan is controlled by the injection-ignition ECU according to a specific logic.

The expansion reservoir (3) 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.

The circuit is equipped with a single engine coolant temperature sensor which measures coolant temperature by means of a double NTC thermistor with negative resistance value. 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 and reaches the thermostat (5) via the cylinder head. If its temperature is lower than 87 °C, the coolant is sucked by the pump (1) via a longitudinal return manifold located between the two cylinder heads. If the temperature is higher than this value, the coolant is conveyed to the radiator 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. A specific fitting (7) on the right-hand cylinder head receives the coolant from a supplementary duct on the head and sends it via two specific pipes to the climate control system heater (8) and to the expansion reservoir (3).