Subaru XT 1988 Service Manual page 198

2-3
ENGINE
2) Remove the oil ring by hand.
Arrange the removed piston rings in good order to prevent
confusion.
CONNECTING ROD
Remove connecting rod cap mounting nuts, and take out
connecting rod from crankshaft.
Arrange removed connecting rod and connecting rod cap in
good order to prevent confusion.
INSPECTION
PISTON AND PISTON PIN
1) Check 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 cyl inder
as instructed in CYLINDER AND PISTON. If any of the
clearances is not to specification, replace the piston or bore
the cylinder to use an oversize piston.
3) Make sure that piston pin can be inserted into the piston
pin hole with a thumb at 20°C (68° F). Replace if defective.
Specifications for piston and piston pin:
Standard outer diameter of piston pin
20.994 - 21.000 mm (0.8265 - 0.8268 in)
Standard inner diameter of piston pin hole
20.999 - 21.009 mm (0.8267 - 0.8271 in)
Standard clearance between piston pin and hole in
piston
0.001 - 0.015 mm (0.00004 - 0.00059 in)
Standard clearance between piston pin and hole in
connecting rod
o -
0.022 mm (0 - 0.0009 in)
PISTON RING
1) If piston ring is broken, damaged, or worn, or if its
tension is insufficient, or when the piston is replaced, replace
piston ring with a new one of the same size as the piston.
"R" or liN" is marked on the end of the top and second rings.
When installing the rings to the piston, face this mark upward.
42
A5-072
Fig.
95
The oil ring is a combined ring consisting of two rails and a
spacer in between. When installing, be careful not to make
misassembly.
Fig.
96
Top ring
~Rmark
Second ring
~
Oil ring Spacer
rr
upper rail
Lower rail
Top ring
g-Nm",
~Nmark
Second ring
~
e .
Upper rail
Oil ring Spacer
Lower rail
A5-073
A5-074
2) Squarely place piston ring in cylinder and measure the
piston ring gap with a th ickness gauge.
---------
Standard Limit
Top 0.20 - 0.35 mm 1.5 mm
ring (0.0079 - 0.0138 in)
(0.059 in)
Piston ring gap
Second 0.20 - 0.35 mm 1.5 mm
ring (0.0079 - 0.0138 in) (0.059 in)
Oil ring
0.3 - 0.90 mm 2.0mm
rail (0.012 - 0.0354 in) (0.079 in)