Subaru Legacy 2005 Service Manual page 1609

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.
(A)
(B)
(C)
(A) Top ring
(B) Second ring
(C) Oil ring
(a) Upper rail
(b) Expander
(c) Lower rail
2) Squarely place the piston ring and oil ring in cyl-
inder, and measure the piston ring gap with a thick-
ness gauge.
Top ring
Piston ring gap Second ring
Oil ring
Cylinder Block
(a)
(b)
(c)
ME-00591
Standard
mm (in)
0.20 — 0.35
(0.0079 — 0.0138)
0.35 — 0.50
(0.0138 — 0.0197)
0.20 — 0.60
(0.0079 — 0.0236)
ME-00592
ME(H6DO)-75
3) Measure the clearance between piston ring and
piston ring groove using thickness gauge.
NOTE:
Before measuring the clearance, clean the piston
ring groove and piston ring.
Clearance
Top ring
between piston
ring and piston
Second ring
ring groove
Clearance between oil ring and oil
ring groove
MECHANICAL
Standard
mm (in)
0.040 — 0.080
(0.0016 — 0.0031)
0.030 — 0.070
(0.0012 — 0.0028)
0.045 — 0.125
(0.0018 — 0.0049)
ME-00178