F2B ENGINE 107 T RAKKER E URO 4/5 PRINT603.93. 641 5432 COOLING Figure 214 Description The engine cooling system works with forced circulation inside closed circuit and can be connected to an additional heater (if any) and to the intarder intercooler. It consists mainly of the following components: - an expansion reservoir whose plug (1) incorporates two valves q discharge and charge q controlling the system pressure. - a coolant level sensor placed at the bottomoftheexpan- sion reservoir with two coupling points. Right drive vehicles: D coupling point for sensor S1 6 .2 litres D coupling point for sensor S2 3 .7 litres Left drive vehicles:
D coupling point for sensor S1 6 litres D coupling point for sensor S2 3 .7 litres - an engine cooling unit to dissipate the heat taken by the coolant from the engine through the intercooler. - a heat exchanger to cool down lubrication oil; - a water pump with centrifugal system incorporated in - an electric fan consisting of a 2-speed electro-magnetic the cylinder block; joint equipped with a neutral wheel shaft hub fitted with a metal plate moving along the axis and where the fan is installed. It is controlled electronically by the vehicle Multiplex system. - a 3-way thermostat controlling the coolant circulation.
Operation The water pump is actuated by the crankshaft through a poli-V belt and sends coolant to the cylinder block, especially to the cylinder head (bigger quantity). When the coolant temperature reaches and overcomes the operating temperature, the thermostat is opened and from here the coolant flows into the radiatorand is cooled down by thefan. The pressure inside the system depe nding on the temperature variation is controlled by the discharge and charge valves incorporated in the expansion reservoir filling plug (1). The discharge valve has a double function:
- keep the systemunder light pressure in order to raisethe Water leaving the thermostat coolant boiling point; Water circulating in the engine - dischargethe pressure surplus in the atmosphereas a re- sult of the coolant high temperature. Water entering the pump The charge valve makes it possible to transfer the coolant from the expansion reservoir to the radiator when a depression is generated inside the system as a result of the coolant volume reduction depending on the fall in the coolant temperature. Discharge valve opening:
D 1 st breather 0.9 bar + 0.2 D 2 nd breather 1.2 bar - 0.1 + 0 - 0.02 + 0.2 - 0.1 Charge valve opening -0.03 bar Cap (1) tightening torque (1) 8 1 Nm 92824 COOLING CIRCUIT VERSION WITHOUT INTARDER Print 603.93.641 Base q November 2006