Page 81
Timing chain, B201 and B202 215-5
2 Fit the camshaft sprocket and move the ~
chain on the sprocket teeth until the marks
on the sprocket and bearing cap coincide.
The O° mark on the crankshaft must be in line
with the timing mark.
Fit the sprocket bolts complete with plain
washers,
Warning
lf the washers are omitted, the bolts will
foul the camshaft carrier.
& Tightening torque for camshaft sprocket:
20 Nm (14.8 Ibf ft)
3 Remove the transit lock from the tensioner,
thereby triggering the device.
Timing chain, B202
The chain tensioner, which is hydraulic and in- |
corporates a spring and ratchet, is fitted inside
the cylinder head and has an opposing action to
the pivoting chain guide.
The fixed guide, which is made of rubber-clad Cy
Steel and has a groove in the rubber for the Pe
chain, is secured by means of two bolts. The
pivoting guide, which is madewof rubber-clad
light alloy, also has a groove for the chain in the
rubber and has a pivot fixing at its lower end.
Saab 900
Page 82
215-6 Timing chain, B201 and B202
Removal and refitting of the timing chain
Before starting work to remove the timing chain,
the O° mark on the flywheel must be turned to line
up with the timing mark on the flywhee! cover or
end plate. The basic settings of the crankshaft
and valve gear must not be altered before the
camshafts or the cylinder head have been re-
moved. Similarly, before the cylinder head is fit-
ted, the crankshaft and valve gear must be set to
their respective timing marks.
Page 83
Timing chain, B201 and B202 215-7
To refit
1 Place the chain on the crankshaft sprocket, | \ .
2 Fit the chain and sprocket on the exhaust- \
valve camshaft. Make sure the chain is taut
between the crankshaft and the camshaft ;
sprockets. Tighten the bolt.
3 Fit the chain and sprocket to the inlet-valve
i camshaft. Keep the chain taut between the Ire
: sprockets while it is being fitted. Tighten the — 2) ie
= bolt. Refer to step 7 below for permitted to-
| lerances in the basic timing setting. % XN
4
°
$2260
¢ Tension the chain tensioner by fully de-
pressing the piston and then rotating it to
&, the locked position.
Ving
Oe) 4a Chain tensioner, early design |
i
pee ry
[szaes Ee
$2271
e Fit the chain tensioner with the piston
under tension. Make sure that the copper
@: gasket is in good condition and that the
sealing surface is clean and free from
burrs.
S276)
Saab 900
Page 84
1
;
215-8 Timing chain, B201 and B202
* Trigger the chain tensioner by pressing
the pivoting chain guide against it: there-
after, press the pivoting guide against
the chain to give the chain its basic ten-
sion.
Use a blunt instrument - not a screwdriver or
similar.
4b
© Check that the chain tensioner maintains
tension on the chain when the pressure
on the chain guide is released and that
the ratchet for the tensioner holds the
chain guide tight against the chain. A li-
mited amount of play will be present until
the hydraulic pressure takes over once
the engine is running.
Chain tensioner, latest design
The latest chain tensioner has a tighter ad-
justment range than earlier versions, thus
providing more-precise compensation for
chain wear and quieter operation.
The function is both mechanical and hyd-
raulic, the tensioning force being provided
by a spring acting on the tensioning arm. A
ratchet prevents return of the tensioning
arm inside the tensioner unit.
Only the latest chain tensioner is carried
as a spare part, the earlier version having
been discontinued.
co
Saab 900
Page 85
7
4
Lez27
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, ©
Timing chain, B201 and B202 215-9
¢ Preset the chain tensioner for fitting by
pressing cown on the ratchet and pushing
in the tensioner.
e Fit the chain tensioner complete with
gasket and tighten to a torque of 65Nm
{52 Ibf ft).
¢ Insert the spring and plastic guide pin
into the tensioner body.
¢ Fit the plug, checking that the ‘0’ ring is
properly seated.
Tighten the plug to 22 Nm (16 Ibf ft).
As the plug is screwed in, the spring will
push the tensioning arm out, thereby ten-
sioning the chain.
Saab 900
Page 86
=
ee mene
215-10 Timing chain, B201 and B202
Warning
New chain tensioners come with the spring
under tension. Never remove the safety pin
(step 4) before the tensioner has been fit-
ted to the engine.
5 Check the setting by rotating the crankshaft
two complete turns in its normal direction of
rotation round to the timing mark. The basic
setting of the camshafts should remain un-
altered. Refer to step 7 for details of permit-
ted tolerances.
Tighten the centre-bolt for the exhaust-valve
camshaft sprocket.
Tightening torque: 63 Nm (47 bf ft)
6 When undoing or tightening the centre-
bolts, hold the camshaft still by means of a
spanner fitted over the flats on the cam-
shaft.
Withdraw the safety pin, whereupon the spring
wifi push the tensioner arm out, thereby tension-
ing the chain.
fd
\
My.
Saab 900
Page 87
ig
|
@: er ee Worn chain
Timing chain, B201 and B202 215-11
7 The adjusting accuracy will depend on the
concition of the chain.
Moving the timing chain one tooth will rotate
the camshaft through 10°, corresponding to
approx, 3.0 mm (0.12 in), which is the width
of the camshaft timing mark.
Camshaft setting
e:
Correct
Exhaust Inlet
Uy or chain retarded
& Mh one tooth
Chain advanced one tooth
Saab 900
Page 88
Crankshaft assembly, B201 and B202 216-1
Crankshaft assembly, B201 and B202
To measure the crankshaft .... . 216-1 To change crankshaftseals .... . 216-4
To measure bearing clearances ... 216-1 To measure drive-belt tension .. . . 216-9
To choose bearing shells for
mainandbig-endbearings .... . 216-3
To measure the crankshaft
Clean the crankshaft and measure the journals,
using a micrometer. Measurements should be
made at several points round the journal. Out-of-
round of the journals and crankpins should not
exceed 0.05mm (0.002in). If the measure-
ments are close to or exceed the stated limit, the
crankshaft should be ground down to undersize
as specified. Journals and crankpins can be
ground down one undersize without rehardening.
Grinding to further undersizes will necessitate
‘Tenifer' rehardening. Check that the crankshaft
is true to within 0.05 mm (0.002 in) using a dial
indicator. Mount the crankshaft in two V-blocks,
place the indicator plunger against the centre
journal and rotate the shaft.
To measure bearing clearance
Before measuring the bearing clearance when
fitting new bearings, check the journal out-of-
round and taper. Bearing clearance is measured
using a 'Plastigage’, which is obtainable under
part no. (45) 3006558 and available in three
thicknesses. Type PG-1 (green) should be used.
Saab 900
Page 89
216-2 Crankshaft assembly, B201 and B202
Main bearings
‘Plastigage’ can be used to measure both out-of-
round and clearance.
1 Position the engine upside-down so that the
weight of the crankshaft will not affect the
measurements.
2 Ensure that the parts to be measured are
free from oil and dirt. Put a strip of ‘Plastig-
| age about 6mm (0.2362 in) to one side of
. the longitudinal centre-line of the journal.
) 3 Refit the bearing cap and tighten to a torque
of 108Nm (80 lbf ft). The crankshaft must
remain stationary while the measurement is
taken.
4 Remove the bearing cap. The strip of 'Plas-
tigage’ should now adhere to the bearing
shell or crankshaft journal.
5 Measure the width of the ‘Plastigage’ strip
using the scale printed on the package and
read off the clearance. One side of the pac-
kage is calibrated in mm, the other side in
thousandths of an inch. Measure the strip at
its widest point but do not touch it with your
fingers.
Big-end bearings
Plastigage strips cannot be used to measure the
out-of-round of big-end bearings with the pistons
fitted in the block. Use a micrometer instead.
Saab 900
Page 90
@
Crankshaft assembly, B201 and B202 216-3
When fitting new bearings, check the big-end
bearing clearance as follows.
1 Rotate the crankpin to be measured to about
60° BTDC.
2 Ensure that the parts to be measured are dry
and free from oil and dirt. Place a strip of
6mm {0.2362 in) Plastigage to one side of
the centre-line of the crankpin.
3 Refit the bearing cap and tighten to a torque
of 54 Nm (40 Ibf ft), The crankshaft must re-
main stationary while the measurement is
taken,
4 Remove the bearing cap. The strip of Plastig-
age should now adhere to the bearing shell
or crankpin.
5 Measure the width of the Plastigage strip
using the scale printed on the package and
read off the clearance. One side of the pac-
kage is calibrated in mm, the other side in
thousandths of an inch. Measure the strip at
its widest point but do not touch it with your
fingers.
Main bearing clearance:
0.020 - 0.062 mm (0.0008 - 0.0024 in)
Big-end bearing clearance
0.026 - 0.062 mm (0.0010 - 0.0024 in)
To choose bearing shells for
main and big-end bearings
Bearing shells are available in two classes for
standard size, ist undersize and 2nd undersize.
The two different thicknesses are can be com-
bined to obtain the correct clearance. Bearing
shells for 3rd and 4th undersizes are only avail-
able in one thickness.
Saab 900