Subaru Legacy 2004 Service Manual page 309

4) Check the snap ring installation groove (A) on
the piston for burr. 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.
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:
• Mark is displayed on the end of top and sec-
ond rings. When installing the rings to the pis-
ton, face these marks upward.
• Oil ring consists of the upper rail, expander
and lower rail. Be careful about the direction of
rail when installing the oil ring to piston.
(A) Upper rail
(B) Expander
(C) Lower rail
Cylinder Block
2) Clean the piston ring groove and piston ring.
3) Squarely place the piston ring and oil ring in cyl-
inder, and measure the piston ring gap with a thick-
ness gauge.
Piston ring
gap
ME-00175
4) Measure the clearance between piston ring and
piston ring groove with a thickness gauge.
Clearance
between pis-
ton ring and
piston ring
groove
(A)
(B)
(C)
(A)
(B)
5. CONNECTING ROD
(C)
1) Replace the connecting rod, if the large or small
end thrust surface is damaged.
2) Check for bend or twist using a connecting rod
aligner. Replace the connecting rod if the bend or
twist exceeds the limit.
ME-00789
ME(H4SO 2.0)-79
Standard mm (in)
0.20 — 0.35
Top ring
(0.0079 — 0.0138)
0.40 — 0.50
2.0 L
(0.0157 — 0.0197)
Second
ring
0.35 — 0.50
2.5 L
(0.0138 — 0.0197)
0.20 — 0.50
Oil ring rail
(0.0079 — 0.0197)
Standard mm (in)
0.040 — 0.080
Top ring
(0.0016 — 0.0031)
0.030 — 0.070
Second ring
(0.0012 — 0.0028)
MECHANICAL
ME-00177
ME-00178