Subaru Impreza 2002 Service Manual page 965

MECHANICAL
4) How to measure the outer diameter of each pis-
ton
Measure the outer diameter of each piston at the
height shown in the figure. (Thrust direction)
CAUTION:
Measurement should be performed at a temper-
ature of 20° ° ° ° C (68° ° ° ° F).
Piston grade point H:
1600 cc and 2000 cc MODEL
40.0 mm (1.575 in)
2500 cc MODEL
37.0 mm (1.457 in)
Piston outer diameter:
1600 cc MODEL
Standard
A: 87.885 — 87.895 mm
(3.4600 — 3.4604 in)
B: 87.875 — 87.885 mm
(3.4596 — 3.4699 in)
0.25 mm (0.0098 in) oversize
88.125 — 88.135 mm
(3.4695 — 3.4699 in)
0.50 mm (0.0197 in) oversize
88.375 — 88.385 mm
(3.4793 — 3.4797 in)
2000 cc MODEL
Standard
A: 91.985 — 91.995 mm
(3.6214 — 3.6218 in)
B: 91.975 — 91.985 mm
(3.6211 — 3.6214 in)
0.25 mm (0.0098 in) oversize
92.225 — 92.235 mm
(3.6309 — 3.6313 in)
0.50 mm (0.0197 in) oversize
92.475 — 92.485 mm
(3.6407 — 3.6411 in)
2500 cc MODEL
Standard
A: 99.485 — 99.495 mm
(3.9167 — 3.9171 in)
B: 99.475 — 99.485 mm
(3.9163 — 3.9167 in)
0.25 mm (0.0098 in) oversize
99.725 — 99.735 mm
(3.9262 — 3.9266 in)
0.50 mm (0.0197 in) oversize
99.975 — 99.985 mm
(3.9360 — 3.9364 in)
CYLINDER BLOCK
5) Calculate the clearance between cylinder and
piston.
CAUTION:
Measurement should be performed at a temper-
ature of 20° ° ° ° C (68° ° ° ° F).
Cylinder to piston clearance at 20 ° ° ° ° C (68 ° ° ° ° F):
Standard
0.010 — 0.030 mm (0.0004 — 0.0012 in)
Limit
0.050 mm (0.0020 in)
6) Boring and honing
(1) If the value of taper, out-of-roundness, or
cylinder-to-piston clearance measured exceeds
the specified limit or if there is any damage on
the cylinder wall, rebore it to use an oversize pis-
ton.
CAUTION:
When any of the cylinders needs reboring, all
other cylinders must be bored at the same time,
and use oversize pistons. Do not perform bor-
ing on one cylinder only, nor use an oversize
piston for one cylinder only.
(2) If the cylinder inner diameter exceeds the
limit after boring and honing, replace the crank-
case.
CAUTION:
Immediately after reboring, the cylinder diame-
ter may differ from its real diameter due to tem-
perature rise. Thus, pay attention to this when
measuring the cylinder diameter.
Limit of cylinder enlarging (boring):
0.5 mm (0.020 in)
ME-88
B2M1305A