Cooling System: Description and Operation

COOLING SYSTEM 5.3 LITRE DESCRIPTION

The cooling system consists of a radiator matrix, a water pump, belt driven by the engine crankshaft and a remote header tank. Two thermostatic valves are fitted, one to each cylinder bank, to ensure rapid warm up from cold.

Under cold-start conditions coolant is forced by the water pump equally through each cylinder block and cylinder head to the thermostatic valve housings. The valves are closed and coolant is therefore returned via the engine cross pipe to the water pump inlet. During this period the radiator is under pump suction and air is bled by jiggle pins in each thermostatic valve.


Note: When fitting a replacement thermostat, the thermostat must be fitted with the jiggle pin at the top of the housing.

The engine contains air pockets which must be purged before effective cooling is possible. The air entrained by the coolant rises to the highest point on each side of the engine, the thermostat housings, then through the jiggle pins to the top of the radiator.

At this time pump suction appears at the heater matrix and the remote headertank carry out an air separation function, in addition to providing a reservoir of coolant.

When coolant temperature rises to a predetermined level, the thermostatic valves open and allow coolant to flow into the top of the radiator.

A thermostatic fan switch is fitted in the water pump suction elbow. The switch starts the radiator electric cooling fan if the temperature of the coolant leaving the radiator rise above a predetermined level. A cooling tube coil is included in the fabrication of the right-hand end tank of the radiator and is connected in series with the automatic transmission hydraulic fluid circulation.

Fig. 1 Coolant Flow:

1. Radiator matrix
2. Water pump
3. Remote header tank
4. Thermostat
5. Cylinder block
6. Cylinder head
7. Engine cross pipe
8. Jiggle pins
9. Coolant temperature switch
10. Auxiliary air valve
11. Heater matrix
12. Thermostatic fan switch
13. Radiator electric cooling fan
14. Transmission fluid cooling tube coil
15. Atmosphere catchment tank
16. Venting jet
17. Engine driven fan
18. Heater water control valve