Subaru 1600 Service Manual page 90

12. Piston and Piston
Pin
I) Check pistons and piston pins
for damage, cracks, and wear and the
piston ring grooves for wear and dam-
age. Replace if defective.
2) Measure the piston-to-cylinder
clearance at each cylinder as instructed
in 11. 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.
13. Piston Ring
1) If piston ring is broken, dam-
aged, 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.
NOTE:
a. "R" or "N" is marked on the end
of the top and second rings. When
installing the rings to the piston.
face this mark upward.
As·on
Fig. 3-101 Mark on piston ring
b. The oil ring is a combined ring con·
sisting of two rails and a spacer in
between. When installing, be careful
not to make misassembly.
ENGINE
--
Specifi~~tions
for pistoIl and piston pin
--
---------------
Standard outer diameter of piston pin
20.992 to 21.000 mm
(0.8265 to 0.8268 in)
1"-----" -------- ----------------
- - - - - - - - - - -
Standard inner diameter of piston pin
20.999 to 21.009 mm
hole (0.8267 to 0.8271 in)
r - - - - - - - - - - - - - - - - - - - - - - - . - - - - - - - - - - _ . -
Standard clearance between piston pin
0.004 to 0.010 mm
and hole in piston
(0.0002 to 0.0004 in)
r---'
Standard clearance between piston pin
0.005 to 0.040 mm
and hole in connecting rod
'----------
- - R m a r k
ToprlOg
D
~Rmark
Second ring
~
Oil
rtng
Fig. 3-102
Top ring
cr '
Upper rail
f--
Spacer AS.073
~lowerralf
Cross section of piston rings
(Riken Piston Ring)
e N mark
~Nmark
Second ring
~
Oil ring
Fig. 3-103
Ei
Upper rail
- Spacer
lower rail
A5-074
Cross section of piston ring
(Nippon Piston Ring)
2) Squarely place piston ring in cyl-
inder and measure the piston ring gap
with a thickness gauge.
NOTE:
If the cylinder is not corrected or
replaced one, measure the piston ring
gap at the bottom of the cylinder,
where the wear is little.
Top ring
Piston ring gap Second ring
Oil ring rail
(0.0002 to 0.0016 in)
1
2 Piston ring
A 5· 296
Fig. 3·104 Measuring piston ring gap
3) Measure the clearance between
piston ring and piston ring groove
with a thickness gauge.
NOTE:
Before measuring the clearance, clean
the piston ring groove and piston ring.
Fig. 3·105 Measuring piston ring
groove clearance
Standard Limit
0.20 - 0.35 mm
I.Omm
(0.0079 - 0.0138 in) (0.039 in)
0.20 - 0.35 mm I.Omm
(0.0079 - 0.0138 in)
(0.039 in)
0.20 - 0.90 mm 1.5 mm
(0.0079 - 0.0354 in)
(0.059 in)