Operation

COOLING SYSTEM – V8

DESCRIPTION AND OPERATION

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The engine driven fan contains a viscous coupling that allows the fan to slip as the engine speed increases. The fan 
is attached to a threaded spigot on the pulley with a left hand threaded nut. The fan draws air through the radiator to 
assist in cooling when the vehicle is stationary.

An electric fan controlled by the engine management system is fitted in front of the radiator assembly.
 

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 ENGINE MANAGEMENT SYSTEM – V8, DESCRIPTION AND OPERATION, Bosch ME 7.2 Engine 

Management System.

Operation
With the engine running, the coolant pump pulley is driven by an ancillary drive belt. When the engine is cold, the 
thermostat is closed and coolant is prevented from circulating through the radiator. Coolant is able to circulate through 
the engine and the passenger compartment heater matrix via a thermostat bypass.

As the temperature increases the thermostat begins to open, allowing cool fluid to be drawn from the radiator bottom 
hose through the pump and into the cylinder block and hot coolant to flow from the coolant pump housing to the 
radiator via the radiator top hose, where it is cooled by air passing through the matrix. When the thermostat opens 
fully, the full flow of coolant passes through the radiator.

Coolant is also drawn through the liquid cooled transmission fluid cooler and the liquid cooled alternator housing by 
the coolant pump via the coolant circuit.

The increased coolant volume, created by heat expansion, is directed to the expansion tank through a bleed hose 
from the top of the radiator. The expansion tank has an outlet hose which is connected into the coolant circuit. This 
outlet hose returns the coolant to the system when the engine cools.