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2003 Chevrolet Corvette Restoration Kit
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 left 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.
Coolant Recovery System
The coolant recovery system consists of a plastic coolant recovery reservoir and overflow tube. The
recovery reservoir is also called a recovery tank or expansion tank. It is partially filled with coolant and is
connected to the radiator fill neck with the overflow tube. Coolant can flow back and forth between the
radiator and the reservoir.
In effect, a cooling system with a coolant recovery reservoir is a closed system. When the pressure in the
cooling system gets too high, it will open the pressure valve in the pressure cap. This allows the coolant,
which has expanded due to being heated, is allowed to flow through the overflow tube and into the
recovery reservoir. As the engine cools down, the temperature of the coolant drops and
a
vacuum is
created in the cooling system. This vacuum opens the vacuum valve in the pressure cap, allowing some
of the coolant in the reservoir to be siphoned back into the radiator. Under normal operating conditions,
no coolant is lost. Although the coolant level in the recovery reservoir goes up and down, the radiator and
cooling system are kept full. An advantage to using a coolant recovery reservoir is that it eliminates
almost all air bubbles from the cooling system. Coolant without bubbles absorbs heat much better than
coolant with bubbles.
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