General Description; Coolant Flow - Isuzu 4JA1 Workshop Manual

6B – 4 ENGINE COOLING

GENERAL DESCRIPTION

COOLANT FLOW

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The engine cooling system consists of the radiator, the water pump, the cooling fan, and the thermostat.
To quickly increase cold engine coolant temperature for smooth engine operation, the coolant is circulated by the
water pump and thermostat through the bypass hose and back to the cylinder body.
The coolant does not circulate through the radiator.
When the coolant temperature reaches specified value, the thermostat will begin to open and a gradually increasing
amount of coolant will circulate through the radiator.
The thermostat will be fully open when the coolant temperature reaches specified value. All of the coolant is now
circulating through the radiator for effective engine cooling.