Subaru 2009 IMPREZA Service Manual page 308

MECHANICAL
5. CONNECTING ROD
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.
Limit of bend or twist per 100 mm (3.94 in) in
length:
0.10 mm (0.0039 in)
( B )
(A) Thickness gauge
(B) Connecting rod
3) Install the connecting rod with bearings attached
to the crankshaft, and measure the thrust clear-
ance using a thickness gauge. If the thrust clear-
ance exceeds the standard or uneven wear is
found, replace the connecting rod.
Connecting rod thrust clearance:
Standard:
0.070 — 0.330 mm (0.0028 — 0.0130 in)
Cylinder Block
( A )
( B )
( A )
ME-00179
ME-00180
ME(H4SO)-90
4) Inspect the connecting rod bearing for scar,
peeling, seizure, melting, wear, etc.
5) Measure the oil clearance on each connecting
rod bearing using plastigauge. If any oil clearance
is not within the standard, replace the defective
bearing with a new part of standard size or under-
size as necessary.
Connecting rod oil clearance:
Standard:
0.016 — 0.044 mm (0.0006 — 0.0017 in)
Bearing size
Bearing
(Thickness at center)
1.492 — 1.501
Standard
(0.0587 — 0.0591)
0.03 (0.0012) 1.510 — 1.513
Undersize (0.0594 — 0.0596)
0.05 (0.0020) 1.520 — 1.523
Undersize (0.0598 — 0.0600)
0.25 (0.0098) 1.620 — 1.623
Undersize (0.0638 — 0.0639)
6) Inspect the bushing at connecting rod small end,
and replace with a new part if worn or damaged.
7) Measure the piston pin clearance at connecting
rod small end. If the measured value is not within
the standard, replace it with a new part.
Clearance between piston pin and bushing:
Standard:
0 — 0.022 mm (0 — 0.0009 in)
Unit: mm (in)
Outer diameter of
crank pin
51.984 — 52.000
(2.0466 — 2.0472)
51.954 — 51.970
(2.0454 — 2.0461)
51.934 — 51.950
(2.0446 — 2.0453)
51.734 — 51.750
(2.0368 — 2.0374)
ME-00181
ME-00174