Fitting Of Pistons In Cylinder Bores; Torquing The Center Main Bearing Cap; Rear Crankshaft Seal Assembly; Measurement Of Piston Clearance - Saab V4 Service Manual

2
ENGINE BODY
ENGINE
Disassembly and reassembly
NOTE
The arrows on the center and front main bearing
caps must point lo the front.
4. Tighten the front and rear bearing caps to a torque
of 98 Nm (72 ft-lb 10.0 kpm). Finger-tighten the bolts
for the center bearing cap.
NOTE
Do not confuse the screws for cylinder heads and
main bearings. These have the same diameter, but
the screws for the main bearings are approx. 0.4
in. (10 mm) longer than those for the cylinder
heads.
As frcm engine No. 7 4900, the cylinder head screws
have been lengthened approx. 0.4 in (10 mm) and
consequently there is no danger of confusion.
5. Press the crankshaft forwards and pry the axial (cen-
ter) bearing cap to the rear. Then, tighten the cap
bolts to a torque of 98 Nm (72
ft~lb
10 kpm) while
holding the crankshaft forward. (This is necessary to
make both halves of the bearing insert equally ready
to bear axially.) See fig.
TORQUING THE CENTER MAIN BEARING CAP
6. Lubricate the inner diameter of the new crankshaft
seal with engine oil and push the seal onto tool
786217. Drive it into the main bearing until it bottoms
out. See fig.
52415
REAR CRANKSHAFT SEAL ASSEMBLY
210-5
FITTING
Of PISTONS IN CYLINDER
BORES
For fitting of pistons in cylinder bores, a feeler gauge with
a width of 1/2 in. is used. In measuring, the piston, with-
out rings, should be placed in the bore in the way in
which it will work subsequently, i. e. with its front marking
pointing forwards in the engine. The feeler gauge should
be connected to a spring balance and placed between
piston and bore at right angles to the piston pin. When
the pull amounts to 9.8 N (2.2 lb 1 kp), the mean clearance
agrees with the thickness of the feeler gauge. Tests should
be carried out at several different depth positions.
Pistons obtained as spare parts are not classified, but
their diameter lies within the upper part of the tolerance
range, so that in most cases the cylinder bore will have
to be honed in order to get the right piston clearance
when a new piston is fitted.
If the clearance obtained is excessive, the cylinder bores
must be drilled to the next oversize. See group 0.
MEASUREMENT OF PISTON CLEARANCE
Oct. 1975