Cooling system operation (Cooling system - L Series)

COOLING SYSTEM OPERATION

The cooling system employed is the bypass type.

When the engine is cold the thermostat closes off the coolant feed from the radiator bottom hose (1). Coolant is drawn via the heater matrix (2) from the top of the cylinder block, this allows some heat transfer to the radiator via the top hose by convection while retaining the majority of the heat within the cylinder block.

The siting of the thermostat (3) in the inlet rather than the outlet side of the system provides a reduced warm up time by circulating a small amount of coolant around a shorter tract, this also prevents temperature build up within the cylinder head prior to the thermostat opening.

A = HOT B = COLD

As temperature increases the thermostat gradually opens, bleeding cool fluid into the cylinder block and allowing hot coolant to flow to the radiator via the top hose (4), balancing the flow of hot and cold fluid to maintain temperature. As the thermostat opens further so the full flow of coolant is drawn through the radiator.

Any excess coolant created by heat expansion is returned to the expansion tank (5) via hose (6).