Subaru Impreza 2002 Service Manual page 966

3. PISTON AND PISTON PIN
1) Check the pistons and piston pins for damage,
cracks, and wear and the piston ring grooves for
wear and damage. Replace if defective.
2) Measure the piston-to-cylinder clearance at
each cylinder. <Ref. to ME-86, CYLINDER AND
PISTON, INSPECTION, Cylinder Block.> If any of
the clearances is not to specification, replace the
piston or bore the cylinder to use an oversize pis-
ton.
3) Make the sure that piston pin can be inserted
into piston pin hole with a thumb at 20°C (68°F).
Replace if defective.
Standard clearance between piston pin and
hole in piston:
Standard
0.004 — 0.008 mm (0.0002 — 0.0003 in)
Limit
0.020 mm (0.0008 in)
4) Check the circlip installation groove on piston for
burr (A). If necessary, remove the burr from groove
so that piston pin can lightly move.
CYLINDER BLOCK
5) Check the piston pin circlip for distortion, cracks
and wear.
4. PISTON RING
1) If the piston ring is broken, damaged, or worn, or
if its tension is insufficient, or when the piston is re-
placed, replace the piston ring with a new one of
the same size as the piston.
CAUTION:
• Marks are shown on the end of top and sec-
ond rings. When installing the rings to piston,
face these marks upward.
• Oil ring is composed of upper rail, expander
and lower rail. Be careful of the rail direction
when installing oil ring to the pisiton.
B2M1401
B2M0084
B2M0420C
ME-89
(A) Upper rail
(B) Expander
(C) Lower rail
MECHANICAL
B2M4595A