Page 11
ADDITIONAL
INSPECTION POINTS
In addition to the normal service inspection
programme, turbo-engine cars have the following additional inspection points:
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ID
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ID
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ID
Emission control programme
Change the spark plugs, adjust the gap
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ID
ID
ID
ID
ID
ID
ID
ID
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..":'
E
E
°E
E
E
E
E
E
E
E
E
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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0
0
0
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0
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Maintenance programme
Check the charging pressure adjusting as necessary
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Check the pressure switch
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Check the seal, charge pressure regulator
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er
Check the fuel booster
Clean the diaphragm housing (charge pressure
regulator)
Change the air cleaner filter
Novo 1977
SAAa
110-1
Page 12
f·
OIL COOLER
Cars with turbocharged engines are equipped with a special engine oil cooler located on the left-hand side of the
car behind the opening in the spoiler. The radiator is connected by means of hoses to an adapter, located between
the oil filter and the filter headpiece.
A thermostat is fitted between the adapter and the
cooler, and it opens when the temperature exceeds about
1670F (750C), allowing the oil to flow through the oil
cooler. f.t lower temperatures, the oil circulates through
the thermostat.
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ENGINE OIL COOLER
1. Oil cooler
2. Thermostat
3. Adapter
CAUTION
OWING TO ITS SYMME,TRICAL DESIGN, IT IS POSSIBLE TO FIT THE THERMOSTAT
ROUND,.IN WHICH CASE THE ENGINE MAY BE DAMAGED.
THE WRONG WAY
Engine side
Cold engine
Warm engine
1670F/
<750C)
«
«
1670F/
<750C)
S 6264
Oil-cooler side
FLOW THROUGH THERMOSTAT
The side of the thermostat that should face the engine is marked by means of a red spot or the word, "inlet".
It is also possible to identify this side of the thermostat as follows:
When the thermostat is cold « 1670F/< 750C), the spring inside the valve will be visible through both holes on the
side of the thermostat that should face the engine.
S 6265
CHECKING THAT THE THEF-lMOSTAT IS THE RIGHT WAY
ROUND
233-1
Nov. 1977
Page 13
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--;-------:---------
....
FUEL SYSTEM
Fuel boosting system at high speeds and high loading
-,
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L-------------------~--~------------~------~S6266
DEVICE FOR FUEL BOOSTING
1. Speed transmitter
2. Throttle valve switch
3. Solenoid valve
4. Pressureregulator
5. Control pressure regulator
6. Fuel distributor
Turbocharged engines are equipped with a special device
to provide the necessary boost in the fuel supply to the
engine under heavy loads and to improve the cooling of
the engine when running at sustained high speeds.
The device consists of a solenoid valve and a pressure
regulator. The valve and pressure regulator are connected
in parallel with the control pressure regulator in the control pressure system.
SOLENOID
VALVE
AND PRESSURE REGULATOR
1. Solenoid valve
2. Pressure regulator
Nov. 1977
-
SA~
240-1
Page 14
Thepressure
regulator
is preset to a pressure
approxima-
Checking the fuel-boosting
function
A. Checking of the throttle valve switch, solenoid valve
and pressure regulator should be carried out in conjunction with measuring of the CO emission as follows:
1. Run the engine until hot, connect the CO meter
and check that the CO content in the exhaust gases
is as specified (1.5 ± 0.5 %)
tely 1 bar lower than that of the control pressure regulator (warm engine), which means that the control pressure
will drop from about 52.6 psi (3.7 bar) to about 38.4 psi
(2.7 bar) when the solenoid
valve opens. This pressure
drop raises the position of the control plunger, which,
in turn, implies a boost in the fuel supply to the engine.
The solenoid valve is energised either by a switch at the
throttle valve which makes the circuit when the throttle
opening is greater than about 1440F (620C), or by
.
-,
means of a transmitter
which is connected
to the speedometer cable and which closes the circuit at speeds in excess of about 80.0 mph (130 km/h).
S 5202
CHECKING THE CO CONTENT
S 5738
VALVE
2. Press in the actuating arm on the throttle valve
switch and keep it depressed. The ·CO value ~hould
now increase to about 4-6 % CO.
SWITCH
1
SPEED TRANSMITTER
PRESSING IN THE THROTTLE
ARM
VALVE SWITCH ACTUATING
3: Release the actuating arm and check that the CO
value is 1.5 ± 0.5 %.
240-2
-
SA~
Nov. 1977
Page 15
EXHAUST
SYSTEM
NOTE
F it the flange so that the side closest to the holes
faces the turbo.
(On later flanges, this side is marked by means of a
spot of paint.)
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S 6268
EXHAUST SYSTEM
The exhaust system on cars with turbocharged engines
comprises pipes of a larger diameter than those on other
Saab 99 models, but the intermediate and rear suspension
points are the same.
The joint between the exhaust pipe and the charge pressure regu lator .consists of a chamfered flange on the
charge pressure regulator, a taper seal ring, swaging on
the exhaust pipe, a loose chamfered flange and three nuts.
Exhaust manifold
The exhaust manifold is secured by means of socket head
screws. A special socket allowing improved access to the
rear screws has been produced. The socket has spare part
No. 83 92 797.
REMOVING THE EXHAUST MANIFOLD
SCREWS
Tool 8392 797
S 5860
THE EXHAUST PIPE CONNECTION TO THE CHARGE PRESSURE REGULATOR
Nov. 1977
-.
252-1
Page 16
EXHAUST
EMISSION
CHECKING
DAMPER
CONTROL
AND ADJUSTING
OF THE THROTTLE
Deceleration function
Checking
On turbocharged
engines,
the vacuum-operated
decelera-
tion valve has been replaced by a mechanical throttle
damper (dash pot) designed to delay the closing of the
throttle.
As a result, combustion
takes place during engine overrun, thereby preventing the emission of unburned hydrocarbons.
1. Run the engine until it has warmed
2. Connect
rev/min.
a tachometer
up properly.
and set the idling speed to 875
3. Increase the engine speed to 3 000 rev/min and use a
stop watch to measure the time between the moment
the throttle is released to the moment that the engine
reaches the speed specified in item 2 above.
The delay time should
be: 3-6 s.
Adjusting
To adjust the delay time, undo the lock nut on the throttle damper and raise (shorter delay time) or lower (longer
delay time) the throttle damper.
THE THROTTL'E<;DJ;l.MPER (DASH POT)
...,-
254-1
Nov. 1977
Page 17
RADIATOR
Removal
FAN
Remove the front body section and radiator and then unbolt and remove the fan unit.
'.
S!iSG2
RADIATOR
FAN
REMOVING THE FAN UNIT
The radiator fan is of new design and is located in front
of the radiator.
The fan hub is in the form of a cover, behind which the
fan motor is mounted.
The fan motor is mounted on the fan cover, which, in
turn, is bolted to the radiator frame.
NOTE
The nut se,curingthe impeller to the impeller shaft
has a left-hand thread.
Nov. 1977
262-1
Page 18
TURBO SYSTEM
which
Supercharging, general
In contrast to conventional
engines, a supercharged
engine provides improved charging on' the induction stroke,
produces
more effective
combustion
of the mix-
ture and an increase in power output and torque. With a
supercharged
engine, it is possible to achieve performance
that is comparable
to that of a larger engine, while, at the
same time, maintaining
the advantages of a smaller engine
with respect to fuel economy, space, weight, etc.
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7
8
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S 6270
TURBO
ENGINE
1. Turbo-compressor
2. Charge pressure regulator
3. Pressure switch
4. Turbo instrument
291-1
5. Suction pipe
6. Pressure pipe
7. Bellows
pipe
8. Exhaust pipe
9. Oil supply
line
10. Oil return line
11. Cooling air pipe
12. Exhaust pressure line
Nov. 1977
Page 19
[,
Turbocharging
Turbocharging is achieved by means of a turbo-compressor which implies utilizing the exhaust gases from the engine to drive the turbine.
The exhaust gases are led to an exhaust gas turbine, causing
the turbine wheel to rotate. The turbine wheel is mounted
on the same shaft as a compressor impeller which rotates
at the same speed.
The compressor is located in the induction system where
it effects an increase in the charging pressure in the combustion chamber.
55865
TURBO·COMPRESSOR
Nov. 1977
Page 20
The Saab Turbo has been designed to start operating at
relatively low engine speeds, in order to provide increased
torque at engine speedstypical of normal driving condi-
relatively high oil flow. Thus, during rotation, the shaft
floats on a film of oil.
The lubricating oil is supplied by the engine lubricating
system through a special line running from the.oil pump.
Return oil flows through a relatively large-bore pipe back
to the sump.
Sealing between the shaft and the bearing housing consists
of sealing rings (piston ring type) installed in grooves in the
shaft.
tions. In contrast to the Saab Turbo, earlier turbochargers
have been designed to provide increased performance,
which implies that they are only utilized at full throttle.
The turbine shaft which rotates at very high speed has
been very accurately balanced. The shaft is mounted in a
floating sliding-contact bearing through which there is a
4
1
E
2
3
-D
5
c
B
o
7
_
Inletair
_
Exhaust gases
A
6
8
TURBO-COMPRESSOR, SECTION
1. Turbin housing
2. Bearing housing
3. Compressor housing
4. Radial bearing
5. Axial bearing
6. Turbo shaft
7. Turbine impeller
8. Compressor impeller
A. From exhaust manifold
B. To exhaust pipe
C. From air cleaner
D. To inlet manifold
E. Lubricating oil line
F. Lubricating oil return pipe
Nov. 1977
291-3
i.