Cooling System: Description and Operation

COMPONENTS




The complete cooling system installed in vehicles with V8 engines incorporates three independent functions: Engine (coolant) cooling; Engine oil cooling; Gearbox oil cooling. Both engine and gearbox oil coolers are mounted in front of the radiator and linked to their separate systems by pre-formed pipes and hoses as shown.





DESCRIPTION
The engine uses a pressurized cooling system and vertical flow radiator, which is supplied from an expansion tank mounted on the RH side of the engine compartment. A belt driven centrifugal water pump, complete with viscous fan, is fitted to the engine front cover and supplies coolant to both banks of cylinders and cylinder heads. A 'four way' thermostat housing, secured to the bottom of the fan cowling, is used to link the main components within the engine cooling system.

OPERATION

When The Engine Is Started From Cold - the thermostat, integral in the housing (2), prevents any coolant circulation through the radiator by closing off the supply from the radiator. During the engine warm up, the water pump (5), pumps coolant around the cylinders to the rear of the engine block and along the galleries in both cylinder banks (15). At the rear of the cylinder block the coolant rises through a large port in both cylinder head/block joint face to the inlet manifold. From the manifold the coolant flow is divided, some directed down the bypass hose (4) and some through the heater feed pipe (10) to the heater matrix (11), which is located within the distribution unit of the heating and ventilation system. The coolant is then carried, via the heater return pipe (12), back to the thermostat housing to complete the first cycle. Within the first, and subsequent cycles, air entering the plenum chamber (16) is heated by a flow of coolant through the supply pipe (8) from the inlet manifold. A bleed pipe (9) then carries the coolant across the engine and back to the expansion tank.

When The Normal Running Temperature Is Reached - the main valve of the thermostat opens, a secondary valve closes the bypass port, and coolant is then circulated through the top hose (6) to the radiator where it is cooled and drawn by the water pump (5) from the base of the radiator. The coolant circulation through the cylinder block and heads to the heater matrix remains the same. An integral bleed pipe (7), fitted to the top of the radiator, runs to the expansion tank and is used to aid coolant filling and control the system pressure. An overflow pipe (14) vents excessive pressure and coolant if the system has been overfilled.