Subaru Legacy 2004 Service Manual page 1192

2) Measure the piston-to-cylinder clearance at
each cylinder. <Ref. to ME(H4DOTC)-79, CYLIN-
DER AND PISTON, INSPECTION, Cylinder
Block.> If any of the clearances is out of specifica-
tion, replace the piston or bore the cylinder to use
an oversize piston.
3) Make sure that the piston pin can be inserted
into the piston pin hole with your 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)
4) Check the snap ring installation groove on the
piston for burr (A). If necessary, remove burr from
the groove so that the piston pin can lightly move.
(A)
5) Check the piston pin snap ring for distortion,
cracks and wear.
Cylinder Block
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 displayed on the end of top and
second rings. When installing the rings to the
piston, face those marks upward.
• Oil ring consists of the upper rail, expander
and lower rail. When installing on piston, be
careful of each rail's direction.
ME-00173
ME-00174
2) Squarely place the piston ring and oil ring in cyl-
inder, and measure the piston ring gap with a thick-
ness gauge.
Piston ring
ME-00175
gap
ME(H4DOTC)-81
(A) Upper rail
(B) Expander
(C) Lower rail
Outer circle side: 0.20 — 0.25
Top ring
Inner circle side: 0.20 — 0.30
Second ring
Oil ring rail
MECHANICAL
(A)
(B)
(C)
(A)
(B)
(C)
ME-00789
Standard
mm (in)
(0.0079 — 0.0098)
(0.0079 — 0.014)
0.40 — 0.50
(0.016 — 0.020)
0.20 — 0.50
(0.0079 — 0.0197)