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Coolant
The engine coolant is a solution made up of a 50-50
mixture of DEX-COOL and suitable drinking water. The
coolant solution carries excess heat away from the
engine to the radiator, where the heat is dissipated to the
atmosphere.
Radiator
The radiator is a heat exchanger. It consists of a core
and two tanks. The aluminum core is a tube and fin
crossflow design that extends from the inlet tank to the
outlet tank. Fins are placed around the outside of the
tubes to improve heat transfer to the atmosphere.
The inlet and outlet tanks are a molded, high
temperature, nylon reinforced plastic material. A high
temperature rubber gasket seals the tank flange edge to
the aluminum core. The tanks are clamped to the core
with clinch tabs. The tabs are part of the aluminum
header at each end of the core.
The radiator also has a drain cock located in the bottom
of the right hand tank. The drain cock unit includes the
drain cock and drain cock seal.
The radiator removes heat from the coolant passing
through it. The fins on the core transfer heat from the
coolant passing through the tubes. As air passes
between the fins, it absorbs heat and cools the coolant.
Pressure Cap
The pressure cap seals the cooling system. It contains a
blow off or pressure valve and a vacuum or atmospheric
valve. The pressure valve is held against its seat by a
spring, which protects the radiator from excessive
cooling system pressure. The vacuum valve is held
against its seat by a spring, which permits opening of the
valve to relieve vacuum created in the cooling system as
it cools off. The vacuum, if not relieved, might cause the
radiator and/or coolant hoses to collapse.
The pressure cap allows cooling system pressure to
build up as the temperature increases. As the pressure
builds, the boiling point of the coolant increases. Engine
coolant can be safely run at a temperature much higher
than the boiling point of the coolant at atmospheric
pressure. The hotter the coolant is, the faster the heat
transfers from the radiator to the cooler, passing air.
The pressure in the cooling system can get too high.
When the cooling system pressure exceeds the rating of
the pressure cap, it raises the pressure valve, venting
the excess pressure.
As the engine cools down, the temperature of the
coolant drops and a vacuum is created in the cooling
system. This vacuum causes the vacuum valve to open,
allowing outside air into the surge tank. This equalizes
the pressure in the cooling system with atmospheric
pressure, preventing the radiator and coolant hoses from
collapsing.
Engine Cooling System:
Surge Tank
The surge tank is a plastic tank that the pressure cap
mounts onto. The tank is mounted at a point higher than
all other coolant passages. The surge tank provides an
air space in the cooling system. The air space allows the
coolant to expand and contract. The surge tank also
provides a coolant fill point and a central air bleed
location. During vehicle use, the coolant heats and
expands. The coolant that is displaced by this expansion
flows into the surge tank. As the coolant circulates, air is
allowed to exit. This is an advantage to the cooling
system. Coolant without bubbles absorbs heat much
better than coolant with bubbles.
Air Baffles and Seals
The cooling system uses deflectors, air baffles and air
seals to increase cooling system capability. Deflectors
are installed under the vehicle to redirect airflow beneath
the vehicle and through the radiator to increase engine
cooling. Air baffles are also used to direct airflow through
the radiator and increase cooling capability. Air seals
prevent air from bypassing the radiator and A/C
condenser, and prevent recirculation of hot air for better
hot weather cooling and A/C condenser performance.
Water Pump
The water pump is a centrifugal vane impeller type
pump. The pump consists of a housing with coolant inlet
and outlet passages and an impeller. The impeller is
mounted on the pump shaft and consists of a series of
flat or curved blades or vanes on a flat plate. When the
impeller rotates, the coolant between the vanes is
thrown outward by centrifugal force.
The impeller shaft is supported by one or more sealed
bearings. The sealed bearings never need to be
lubricated. Grease cannot leak out, dirt and water cannot
get in as long as the seal is not damaged or worn.
The purpose of the water pump is to circulate coolant
throughout the cooling system. The water pump is driven
by the crankshaft via the timing chain.
Thermostat
The thermostat is a coolant flow control component. It's
purpose is to help regulate the operating temperature of
the engine. It utilizes a temperature sensitive wax-pellet
element. The element connects to a valve through a
small piston. When the element is heated, it expands
and exerts pressure against the small piston. This
pressure forces the valve to open. As the element is
cooled, it contracts. This contraction allows a spring to
push the valve closed.
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Troubleshooting
