Water Pump; Thermostat - Toyota 22R-E Service Manual

EG1–224
avoiding needless coolant loss. To find out if the coolant needs to be replenished, check the
reservoir tank level.

WATER PUMP

The water pump is used for forced circulation of coolant through the cooling system. It is
mounted on the front of the timing chain cover and driven by a V belt.

THERMOSTAT

The thermostat is a wax type and is mounted in the water outlet housing. The thermostat includes
a type of automatic valve operated by fluctuations in the coolant temperature. When the coolant
temperature drops, the valve closes, preventing the circulation of coolant through the engine and
thus permitting the engine to warm up rapidly. When the coolant temperature has risen, the valve
opens, allowing the coolant in the engine to circulate through the radiator. Wax inside the
thermostat expands when heated and contracts when cooled. Heating the wax thus generates
pressure which overpowers the force of the spring which keeps the valve closed, thus opening
the valve. When the wax cools, its contraction causes the force of the spring to take effect once
more, closing the valve. The thermostat in this engine operates at a temperature of 88SC (190SF).
PREPARATION
RECOMMENDED TOOLS
EQUIPMENT
Heater
Radiator cap tester
Thermometer
Torque wrench
ENGINE
09082–00015 TOYOTA Electrical Tester
– COOLING SYSTEM