Opel 1900 1973, Service Manual

Page: 354 / 625

EMISSION CONTROL SYSTEMS
6 3
2. With the engine “OFF”, observe damper door
position through snorkel opening. If position of snor-
kel makes observation difficult “se the aid of a mir-
ror. At this point damper door should be in such a
position that the heat stove passage is covered (snor-
kel passage open). If not, check for binds in linkage.
3. Apply at least nine in. Hg. of to dia-
phragm assembly through hose disconnected at sen-
sor “nit. This can be done by mouth. Damper door
should completely close snorkel passage when
is applied. If not, check to see if linkage is
hooked correctly and for a vacuum leak.
4. With applied, bend or clamp hose to trap
in diaphragm assembly. Damper door
should remain in position (closed snorkel passage). If
it does not, there is a leak in diaphragm
assembly. Replace diaphragm assembly.
Sensor Check
Quick Check of System:
1. Start test with engine cold, air cleaner at a temper-
ature below 85 degrees. If the engine has been in
recent “se, allow it to cool.
2. Observe the air door before starting the engine: it
should be closed.
3. Start the engine and allow it to idle. Immediately
after starting the engine, the air door should open.
4. As the engine warms up, the air door should start
to close, and the air cleaner should become warm to
the hand.
5. The system is operating normally as described
above. If the air cleaner fails to operate as above or
if correct operation of the air cleaner is still in doubt,
proceed to the thermometer check.
Thermometer Check of Sensor:
1. Start test with air cleaner temperature below 85
degrees. IF ENGINE HAS BEEN RUN RE-
CENTLY, ALLOW IT TO COOL DOWN. While
engine is cooling, remove air cleaner cover and in-
stall a temperature gage such as 22973 as close as
possible to air cleaner cover. Let car
stand idle for hour or more before proceeding to
step 2.
2. Start the engine. Air door should open immedi-
ately if engine is cool enough. When air door starts
to close (in a few minutes), remove air cleaner cover
and read temperature gage. It
read 115 degrees
plus or minus 20 degrees.
3. If air door does not start to close at temperature
indicated, temperature sensor is defective and must
be replaced.
EXHAUST GAS RECIRCULATION SYSTEM
T e s t i n g
The exhaust gas recirculation valve is to be checked
at 12,000 mile intervals “sing the following proce-
dure:
1. With engine at operating temperature, connect a
tachometer to engine and note R.P.M. at idle.
2. Disconnect hose at the intake manifold
that goes to the air cleaner.
3. Disconnect hose for exhaust gas recircula-
tion valve from the throttle valve and connect it to
the intake manifold where hose to air
cleaner was connected.
4.
Engine speed should decrease between
R.P.M. from previously noted R.P.M.
5. If the R.P.M. decrease is less than 100 R.P.M., the
exhaust gas recirculation valve and fitting going into
the intake manifold must be removed, cleaned, and’
reinstalled.
MAINTENANCE AND ADJUSTMENTS
EXHAUST GAS RECIRCULATION SYSTEM
Cleaning
Clean the exhaust gas recirculation valve and fitting
with a piece of stiff wire removing all exhaust depos-
its.
C A U T I O N :
Do not soak in solvent.
the valve and fitting, check op
as outlined under “Testing”. If
does not operate properly after a
thorough cleaning, replace it.
MAJOR REPAIR
REMOVAL AND REPLACEMENT OECS UNITS
The damper door is not serviceable. The air cleaner
assembly must be replaced if the damper door is
defective.
And Vacuum Motor
1. Remove motor retainer spring. See Figure