Subaru Legacy IV (2008 year). Manual - part 72

ME(H4SO)-84

Cylinder Block

MECHANICAL

6) Boring and honing

(1) If any of the measured value of taper, out-of-
roundness or cylinder-to-piston clearance is out
of standard or if there is any damage on the cyl-
inder wall, rebore it to replace with an oversize
piston.

CAUTION:
When any of the cylinders needs reboring, oth-
er cylinders must be bored at the same time,
and replaced with oversize pistons.

(2) If the cylinder inner diameter exceeds the
limit after boring and honing, replace the cylin-
der block.

NOTE:
Immediately after reboring, the cylinder diameter
may differ from its real diameter due to temperature
rise. Thus, when measuring the cylinder diameter,
wait until it has cooled to room temperature.

Cylinder inner diameter boring limit (diameter):

To 100.005 mm (3.9372 in)

3. PISTON AND PISTON PIN

1) Check the piston and piston pin for breaks,
cracks or wear. Replace if faulty.
2) Check the piston ring groove for wear and dam-
age. Replace if faulty.
3) Make sure that the piston pin can be inserted
into the piston pin hole with a thumb at 20°C (68°F).
Replace if faulty.

Clearance between piston hole and piston pin:

Standard

0.004 — 0.008 mm (0.0002 — 0.0003 in)

4) Check the snap ring installation groove (A) on
the piston for burr. If necessary, remove burr from
the groove so that the piston pin can lightly move.

5) Check the piston pin snap ring for distortion,
cracks and wear.

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 part of
the same size as piston.

NOTE:
• The top ring and second ring have the mark to
determine the direction for installing. When install-
ing the ring to piston, face these marks to the top
side.
• Oil ring consists of the upper rail, expander and
lower rail. When installing the oil ring on piston, be
careful of each rails direction.

ME-00173

ME-00174

(A) Upper rail

(B) Expander

ME-00175

(A)

ME-02480

(A)

(B)

(C)

(A)

(B)

(C)

ME(H4SO)-85

Cylinder Block

MECHANICAL

2) Using the piston, insert the piston ring and oil
ring into the cylinder so that they are perpendicular
to the cylinder wall, and measure the piston ring
gap with a thickness gauge.

3) Fit the piston ring straight into the piston ring
groove, then measure the clearance between pis-
ton ring and piston ring groove with a thickness
gauge.

NOTE:
Before measuring the clearance, clean the piston
ring groove and piston ring.

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)

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)

4) Inspect the connecting rod bearing for scar,
peeling, seizure, melting, wear, etc.

Standard

mm (in)

Piston ring gap

Top ring

0.20 — 0.35

(0.0079 — 0.0138)

Second ring

0.37 — 0.52

(0.0146 — 0.0205)

Oil ring rail

0.20 — 0.50

(0.0079 — 0.0197)

Standard

mm (in)

Clearance between
piston ring and
piston ring groove

Top ring

0.040 — 0.080

(0.0016 — 0.0031)

Second ring

0.030 — 0.070

(0.0012 — 0.0028)

ME-00177

ME-00178

(A) Thickness gauge

(B) Connecting rod

( A )

( B )

ME-00179

ME-00180

ME(H4SO)-86

Cylinder Block

MECHANICAL

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)

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)

8) The replacement procedure for the connecting
rod small end bushing is as follows.

(1) Remove the bushing from connecting rod
with ST and press.
(2) Press the bushing with the ST after applying
oil on the periphery of new bushing.

499037100

CONNECTING ROD
BUSHING REMOVER AND
INSTALLER

(3) Make two 3 mm (0.12 in) holes in the
pressed bushing to match the pre-manufac-
tured holes on the connecting rod, then ream
the inside of the bushing.
(4) After completion of reaming, clean the bush-
ing to remove chips.

6. CRANKSHAFT AND CRANKSHAFT
BEARING

1) Clean the crankshaft completely, and check it for
cracks using liquid penetrant tester. If defective, re-
place the crankshaft.
2) Measure the bend of crankshaft. If it exceeds the
limit, correct or replace it.

NOTE:
If a suitable V-block is not available, using just the
#1 and #5 crankshaft bearings on cylinder block,
position the crankshaft on cylinder block. Then,
measure the crankshaft bend using a dial gauge.

Crankshaft bend limit:

0.035 mm (0.0014 in)

Unit: mm (in)

Bearing

Bearing size

(Thickness at center)

Outer diameter of

crank pin

Standard

1.492 — 1.501

(0.0587 — 0.0591)

51.984 — 52.000

(2.0466 — 2.0472)

0.03

(0.0012)

Undersize

1.510 — 1.513

(0.0594 — 0.0596)

51.954 — 51.970

(2.0454 — 2.0461)

0.05

(0.0020)

Undersize

1.520 — 1.523

(0.0598 — 0.0600)

51.934 — 51.950

(2.0446 — 2.0453)

0.25

(0.0098)

Undersize

1.620 — 1.623

(0.0638 — 0.0639)

51.734 — 51.750

(2.0368 — 2.0374)

ME-00181

ME-00174

ME-00182

ME-00183

ME(H4SO)-87

Cylinder Block

MECHANICAL

3) Inspect the crank journal and crank pin for wear.
If they are not within the specification, replace the
bearing with a suitable (undersize) one, and re-
place or grind to correct the crankshaft as neces-
sary. When grinding the crank journal or crank pin,
finish them to the specified dimensions according
to the undersize bearing to be used.

Crank pin:

Out-of-roundness

0.003 mm (0.0001 in)

Cylindricality

0.004 mm (0.0002 in)

Grinding limit (dia.)

To 51.750 mm (2.0374 in)

Crank journal:

Out-of-roundness

0.005 mm (0.0002 in)

Cylindricality

0.006 mm (0.0002 in)

Grinding limit (dia.)

To 59.758 mm (2.3527 in)

ME-00184

Unit: mm (in)

Crank journal outer diameter

Crank pin outer diameter

#1, #3

#2, #4, #5

Standard

Journal O.D.

59.992 — 60.008

(2.3619 — 2.3625)

59.992 — 60.008

(2.3619 — 2.3625)

51.984 — 52.000

(2.0466 — 2.0472)

Bearing size
(Thickness at center)

1.998 — 2.011

(0.0787 — 0.0792)

2.000 — 2.013

(0.0787 — 0.0793)

1.492 — 1.501

(0.0587 — 0.0591)

0.03 (0.0012)
Undersize

Journal O.D.

59.962 — 59.978

(2.3607 — 2.3613)

59.962 — 59.978

(2.3607 — 2.3613)

51.954 — 51.970

(2.0454 — 2.0461)

Bearing size
(Thickness at center)

2.017 — 2.020

(0.0794 — 0.0795)

2.019 — 2.022

(0.0795 — 0.0796)

1.510 — 1.513

(0.0594 — 0.0596)

0.05 (0.0020)
Undersize

Journal O.D.

59.942 — 59.958

(2.3599 — 2.3605)

59.942 — 59.958

(2.3599 — 2.3605)

51.934 — 51.950

(2.0446 — 2.0453)

Bearing size
(Thickness at center)

2.027 — 2.030

(0.0798 — 0.0799)

2.029 — 2.032

(0.0799 — 0.0800)

1.520 — 1.523

(0.0598 — 0.0600)

0.25 (0.0098)
Undersize

Journal O.D.

59.742 — 59.758

(2.3520 — 2.3527)

59.742 — 59.758

(2.3520 — 2.3527)

51.734 — 51.750

(2.0368 — 2.0374)

Bearing size
(Thickness at center)

2.127 — 2.130

(0.0837 — 0.0839)

2.129 — 2.132

(0.0838 — 0.0839)

1.620 — 1.623

(0.0638 — 0.0639)

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