Cooling System; Operation - Toyota 22R-E Service Manual

COOLING SYSTEM

DESCRIPTION
This engine is cooled by a pressurized water forced circulation cooling system equipped with a
thermostatically controlled by – pass valve mounted on the inlet side.

OPERATION

The cooling system is composed of the water jacket (inside the cylinder block and cylinder head),
radiator, water pump, thermostat, cooling fan, fluid coupling, hoses and other components.
Engine coolant, which has been heated in the water jacket, is drawn into the radiator by the water
pump. The radiator is cooled by air drawn in by the cooling fan and by the air flow from the
vehicle's forward motion. This in turn cools the coolant in the radiator. The coolant is then drawn
into the water pump and then discharged back to the cylinder block.
The water jacket is a network of channels in the outer area of the cylinder block and cylinder
head. It is designed so that the engine coolant flowing through it can provide adequate cooling to
the areas subjected to the highest thermal stresses, in particular, the cylinders and combustion
chambers, during engine operation.
RADIATOR
The radiator, mounted at the front of vehicle, consists of an upper and lower tank and a core
connecting the two tanks.
The core contains many tubes through which engine coolant flows from the upper tank to the
ENGINE – COOLING SYSTEM
EG2–261