System - Datsun 1973 510 Repair Manual

I
J
L
10lt l
k
I
y
4
I
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I
I
I
I
I
I
I
r
I
t
Emission Controls
and Fuel
System
tam
unburned
hydrocarbons
The crank
case
emiSSIOn
control eqUIpment
recy
cles these gases
back
mto
the
engme
combustIOn
chamber
where they
are
burned
Crankcase
gases
are
recycled
m
the fol
lowmg
manner
while
the engme
IS run
mng
clean filtered
aIr
IS
drawn
mto
the
crankcase
through
the
carburetor
mto
the
crankcase
through
the carburetor
aIr
filter
and then
through
a
hose
leadmg to
the
rocket
cover
As
the
aIr passes
through
the crankcase
It
picks
up
the combustion
The crankcase
emiSSIOn
control
eqUlp
gases
and
carnes
them
out
of the crank
ment conSIsts
of
a
pOSItIve crankcase
ven case
up
through the
PCV
valve and
mto
tllatlon valve
PCV
a
closed
or
open
OIl
the
mtake mamfold After they
enter
the
filler
cap
and
hoses
to connect
thiS
eqUlp
mtake mamfold
they
are
drawn
mto
the
ment
combustIon chamber and burned
When the
engme
IS
runnmg
a
small The
most
cntIcal
component
m
the
sys
portIOn of the
gases
whICh
are
formed
m
tern
IS
the PCV
valve ThiS
vacuum con
the combustion chamber
durmg
combus trolled valve
regulates
the
amount
of
tlon
leak by the piston
nngs
and enter the
gases
whICh
are
recycled mto
the
com
crankcase
Smce
these
gases
are
under bustIon chamber
At
low
engme
speeds
pressure
they tend
to escape
from the the valve
IS
partIally closed hmltIng
the
crankcase and
enter mto
the atmosphere flow of
gases
mto
the mtake mamfold
As
If these
gases
were
allowed
to
remam m
engine
speed
mcreases
the valve
opens
the crankcase for
any
length
of
time
they
to
admIt greater quantitIes of the
gases
would
contammate
the
engme
OIl and
mto
the mtake manIfold If the valve
cause
sludge
to
buIld
up
If the
gases
are
should become blocked
or
plugged
the
allowed
to escape mto
the
atmosphere
gases
WIll be
prevented
from
escapmg
they would pollute the
aIr as
they
con
from the crankcases
by
the normal
route
105
Emission
Controls
There
are
three types of
automotive
pollutants crankcase fumes exhaust
gases
and
gasohne
evaporation
The
eqUIpment that
IS
used
to
hmlt these
pol
lutants
IS
commonly
called
emiSSIOn con
trol eqUIpment
CRANKCASE
EMISSION
CONTROLS