Mazda 121 - Positive Crankcase Ventilation (PCV) System Description; PCV Valve Inspection

POStrtvE
GRANKCASE
VENTILATION
(PCV)
SYSTEM
F
posrilvE
GRANKCASE
VENTILATION
(PCU
SYSTEM
DESCNIPTION
The
PCV valve is operated by the
intake manifold
vacuum.
When the engine
is running at idle, the
PCV valve
is opened slightly and a
small amount
of blowby
gas
is drawn
into
the
intake manifold to be burned.
Asthe enginespeed risesthe
PCV valve is opened
further, allowing a
proportionately largeramountot blow-
by
gas
to be drawn into the intake
manifold.
PCV VALVE
Inspectlon
1. Warm up the
engine to
normal operatlng
lemperature and
run it at idle.
2. Disconnect the
PCV valve andthe
ventilation
hose from the
cylinder
head cover.
3. Block the
PCV valve opening.
4. Verify that
vacuum is telt.
5. Remove the
PCV valve.
6. Blow
through the
valve from
port
@
and verify that airflows
lrom ot
gort
6).
7.
Blow thrbughl-he
valve
flom
port
@
and
verity that no air-
flows kom of
port
@.
8. Reolace the
PCV valve if not
as specified.
F-99