Radiator Cap - Suzuki SY413 Service Manual

6B-4 ENGINE COOLING
At air bleed
At valves closed
At pressure relief
At vacuum relief
1. Pressure valve
2. Ventilation valve
3. From reservoir tank

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 predeter-
mined strength which protects the cooling system by relieving the
pressure if the pressure in cooling system rises by 90 kPa (0.9 kg/
2
cm , 12.8 psi).
The ventilation valve operates as follows.
D 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.
D It closes when the engine has warmed up and the pressure in
the radiator has risen.
D 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 vacuum 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 neces-
sary.
4. To reservoir tank
5. Pressure in radiator
WARNING:
As long as there is pressure in the cooling system, the
temperature can be considerably higher than the boil-
ing 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 con-
tains flammable anti-freeze such as alcohol (not rec-
ommended for use at any time), there is also the
possibility or causing a serious fire.