Sidekick JS 2D 2WD L4-1.6L (1998)
Radiator Cap: Description and Operation
RADIATOR CAP
A pressure-vent cap is used on the radiator. The cap contains a pressure valve and ventilation valve. The pressure valve is held against its seat by a
spring of predetermined strength which protects the cooling system by relieving the pressure if the pressure in cooling system rises by 90 kPa (0.9
kg/cm2, 12.8 psi).
VENTILATION VALVE
The ventilation valve operates as follows.
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It opens to let the air out of the radiator when the temperature and the pressure in the radiator are lower than ventilation valve weight.
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It closes when the engine has warmed up and the pressure in the radiator has risen.
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It opens when the engine has cooled after being warmed up once and vacuum has occurred in the radiator so as to prevent the coolant level in the
radiator from falling and the radiator from being collapsed due to the vaccum in it.
NOTE: Do not remove radiator cap to check engine coolant level; check coolant visually at the see-through coolant reservoir tank. Coolant should be
added only to reservoir tank as necessary.
WARNING: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the
solution in the radiator without causing the solution to boil. Removal of the radiator cap while engine is hot and pressure is high will cause the solution
to boil instantaneously and possibly with explosive force, spewing the solution over engine, fenders and person removing cap. If the solution contains
flammable anti-freeze such as alcohol (not recommended for use at any time), there is also the possibility or causing a serious fire.