Idiomas disponibles
Idiomas disponibles
coolant and the reservoir is only half full.
When the engine starts and beings to warm up, the coolant and the reservoir is only half full.
When the engine starts and begins to warm up, the coolant expands and is forced out through the pressure
valve into the reservoir.
When the engine stops and cools down, the vacuum created in the radiator by the contracting coolant and
the upper sealing seat of the cap allow coolant to be drawn back into the system from the reservoir.
The closed system eliminates practically all air in the system and ensures the radiator; heater and engine
block are always in a coolant environment. Coolant is added through the reservoir and the radiator filler
neck, eliminating the need to remove the pressure cap routinely. This practicality led to the closed system
being used on most cars today.
Note: Although routine removal of the cap is not recommended, it should be replaced just as often as open
cooling system caps.
THE PRESSURE CAP
The pressure cap is the safety valve of the cooling system because as it allows for working temperature
above boiling point, it limits the amount of pressure build-up for safety.
The pressure cap is comprised of the following components:
1. The cap itself, which has two ears to allow for engagement with the filler neck cams. As system pressure
is increase the ears are retained more tightly on the cams. The filler neck cams are built in a way that the
pressure valve is pressed on the filler neck with exactly the right amount of pressure. The cams also have a
safety stop.
2. A spring disc diaphragm which seals against the top of the filler neck and provides friction to hold the cap
in place. On closed systems, an upper sealing gasket which seals the atmospheric pressure.
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