The cooling system is composed of the water jacket (inside the cylinder block and cylinder head), radiator, water
pump, thermostat, electric fan, hoses and other components.
Coolant which is heated in the water jacket is pumped to the radiator, through which an electric fan blows air
to cool the coolant as it passes through. Coolant which has been cooled is then sent back to the engine by the
water pump, where it cools the engine.
The water jacket is a network of channels in the shell of the cylinder block and cylinder head through which cool-
ant passes. It is designed to provide adequate cooling of the cylinders are combustion chambers which become
heated during engine operation.
RADIATOR
The radiator performs the function of cooling the coolant which has passed through the water jacket and become
hot, and it is mounted in the front of the vehicle. The radiator consists of an upper tank and lower tank, and a
core which connects the two tanks. The upper tank contains the inlet for coolant from the water jacket and the
filler inlet. It also has a hose attached through which excess coolant or steam can flow. The lower tank has an
outlet and drain cock for the coolant. The core contains many tubes through which coolant flows from the upper
tank to the lower tank as well as cooling fins which radiate heat away from the coolant in the tubes. The air
sucked through the radiator by the electric fan, as well as the wind generated by the vehicle’s travel, passes
through the radiator, cooling the coolant. Models with automatic transmission include an automatic transmission
fluid cooler built into the lower tank of the radiator. A fan with an electric motor is mounted behind the radiator
to assist the flow of air through the radiator. The fan operates when the coolant temperature becomes high in
order to prevent it from becoming too high.
RADIATOR CAP
The radiator cap is a pressure type cap which seals the radiator, resulting in pressurization of the radiator as
the coolant expands. The pressurization prevents the coolant from boiling even when the coolant temperature
exceeds 100
°
C (212
°
F). A relief valve (pressurization valve) and a vacuum valve (negative pressure valve) are
built into the radiator cap. The relief valve opens and lets steam escape through the overflow pipe when the
pressure generated inside the cooling system exceeds the limit (coolant temperature: 110–120
°
C, 230–248
°
F,
pressure; 0.3–1.0 kg/cm
2
, 4.3–14.2 psi, 29.4–98.1 kPa). The vacuum valve opens to alleviate the vacuum which
develops in the coolant system after the engine is stopped and the coolant temperature drops. The valve’s open-
ing, allows the coolant in the reservoir tank to return to the cooling system.
RESERVOIR TANK
The reservoir tank is used to catch coolant which overflows the cooling system as a result of volumetric expan-
sion when the coolant is heated. The coolant in the reservoir tank returns to the radiator when the coolant tem-
perature drops, thus keeping the radiator full at all times and avoiding needless coolant loss. Check the reservoir
tank level to learn if the coolant needs to be replenished.
WATER PUMP
The water pump is used for forced circulation of coolant through the cooling system. It is mounted on the front
of the cylinder block and driven by a timing belt.
THERMOSTAT
The thermostat has a wax type bypass valve and is mounted in the water inlet housing. The thermostat includes
a type of automatic valve operated by fluctuations in the coolant temperature. This valve closes when the cool-
ant temperature drops, preventing the circulation of coolant through the engine and thus permitting the engine
to warm up rapidly. The valve opens when the coolant temperature has risen, allowing the circulation of coolant.
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 82
°
C (180
°
F).
–
COOLING SYSTEM
Operation
CO–3
Summary of Contents for 2VZ-FE
Page 1: ...ENGINE MECHANICAL EM 1 ENGINE MECHANICAL Description Operation ...
Page 31: ...CYLINDER HEADS COMPONENTS EM 29 ENGINE MECHANICAL Cylinder Heads ...
Page 63: ...CYLINDER BLOCK REMOVAL OF ENGINE EM 61 ENGINE MECHANICAL Cylinder Block ...
Page 64: ...EM 62 ENGINE MECHANICAL Cylinder Block ...
Page 71: ...COMPONENTS EM 69 ENGINE MECHANICAL Cylinder Block ...
Page 106: ...EFI SYSTEM FI 1 ...
Page 107: ...DESCRIPTION FI 2 EFI SYSTEM Description ...
Page 111: ...OPERATION System Circuit FI 4 EFI SYSTEM Operation System Circuit ...
Page 121: ...FUEL SYSTEM Fuel Pump EFI SYSTEM Fuel System Fuel Pump FI 15 ...
Page 141: ...Fuel Tank and Lines COMPONENTS EFI SYSTEM Fuel System Fuel Tank and Lines FI 35 ...
Page 172: ...EXHAUST SYSTEM EXHAUST SYSTEM REPAIR INSTRUCTIONS EX 1 ...
Page 174: ...EMISSION CONTROL SYSTEMS EC 1 ...
Page 186: ...COOLING SYSTEM CO 1 ...
Page 205: ...LUBRICATION SYSTEM LUBRICATION SYSTEM Description Operation LU 1 ...
Page 224: ...IGNITION SYSTEM IG 1 ...
Page 237: ...SERVICE SPECIFICATIONS IG 14 IGNITION SYSTEM ServiceSpecifications ...
Page 238: ...ENGINE TROUBLESHOOTING TR 1 ...