Subaru Impreza 2003 Service Manual page 297

2. CYLINDER AND PISTON
1) The cylinder bore size is stamped on cylinder
block's front upper surface.
NOTE:
• Measurement should be performed at a temper-
ature 20°C (68°F).
• Standard sized pistons are classified into two
grades, "A" and "B". These grades should be used
as a guide line in selecting a standard piston.
Standard diameter:
1.6 L model
A: 87.905 — 87.915 mm (3.4608 — 3.4612 in)
B: 87.895 — 87.905 mm (3.4604 — 3.4608 in)
2.0 L model
A: 92.005 — 92.015 mm (3.6222 — 3.6226 in)
B: 91.995 — 92.005 mm (3.6218 — 3.6222 in)
2.5 L model
A: 99.505 — 99.515 mm (3.9175 — 3.9179 in)
B: 99.495 — 99.505 mm (3.9171 — 3.9175 in)
(B)
(A)
#5
#4
#3
#2
#1
(E) (C)
(A) Main journal size mark
(B) Cylinder block RH-LH combination mark
(C) #1 cylinder bore size mark
(D) #2 cylinder bore size mark
(E) #3 cylinder bore size mark
(F) #4 cylinder bore size mark
CYLINDER BLOCK
(F)
(D)
ME-00170
ME(H4SO)-85
2) How to measure the inner diameter of each cyl-
inder
Measure the inner diameter of each cylinder in both
the thrust and piston pin directions at the heights
shown in the figure, using a cylinder bore gauge.
NOTE:
Measurement should be performed at a tempera-
ture 20°C (68°F).
Taper:
Standard
0.015 mm (0.0006 in)
Limit
0.050 mm (0.0020 in)
Out-of-roundness:
Standard
0.010 mm (0.0004 in)
Limit
0.050 mm (0.0020 in)
(A)
(A) Piston pin direction
(B) Thrust direction
H1 10 mm (0.39 in)
H2 45 mm (1.77 in)
H3 80 mm (3.15 in)
H4 115 mm (4.35 in)
3) When the piston is to be replaced due to general
or cylinder wear, determine a suitable sized piston
by measuring the piston clearance.
MECHANICAL
(B)
H1
H2
H3
H4
ME-00171