1997 SUBARU LEGACY service

3. CRANKSHAFT AND PISTON
G2M0168
1) Remove connecting rod cap.
2) Remove connecting rod bearing.
CAUTION:
Arrange removed connecting rod, connecting rod cap
and bearing in order to prevent confusion.
3) Remove piston rings using the piston ring expander.
4) Remove the oil ring by hand.
CAUTION:
Arrange the removed piston rings in good order to
prevent confusion.
5) Remove circlip.
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2-3bSERVICE PROCEDURE
5. Cylinder Block

C: INSPECTION
1. CYLINDER BLOCK
1) Check for cracks and damage visually. Especially,
inspect important parts by means of red lead check.
2) Check the oil passages for clogging.
3) Inspect crankcase surface that mates with cylinder
head for warping by using a straight edge, and correct by
grinding if necessary.
Warping limit:
0.05 mm (0.0020 in)
Grinding limit:
0.1 mm (0.004 in)
Standard height of cylinder block:
201.0 mm (7.91 in)
B2M0082A
2. CYLINDER AND PISTON
1) The cylinder bore size is stamped on the cylinder
block’s front upper surface.
NOTE:
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:
A: 99.505—99.515 mm (3.9175—3.9179 in)
B: 99.495—99.505 mm (3.9171—3.9175 in)
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2-3bSERVICE PROCEDURE
5. Cylinder Block

G2M0170
2) How to measure the inner diameter of each cylinder
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.
CAUTION:
Measurement should be performed at a temperature
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)
3) When piston is to be replaced due to general or cylin-
der wear, determine a suitable sized piston by measuring
the piston clearance.
B2M1305A
4) How to measure the outer diameter of each piston
Measure the outer diameter of each piston at the height
shown in the Figure. (Thrust direction)
CAUTION:
Measurement should be performed at a temperature of
20°C (68°F).
Piston grade point H:
37.0 mm (1.457 in)
Piston outer diameter:
Standard
A: 99.485—99.495 mm (3.9167—3.9171 in)
B: 99.475—99.485 mm (3.9163—3.9167 in)
0.25 mm (0.0098 in) oversize
99.725—99.735 mm (3.9262—3.9266 in)
0.50 mm (0.0197 in) oversize
99.975—99.985 mm (3.9360—3.9364 in)
5) Calculate the clearance between cylinder and piston.
CAUTION:
Measurement should be performed at a temperature of
20°C (68°F).
Cylinder to piston clearance at 20°C (68°F):
Standard
0.010—0.030 mm (0.0004—0.0012 in)
Limit
0.050 mm (0.0020 in)
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2-3bSERVICE PROCEDURE
5. Cylinder Block

6) Boring and honing
(1) If the value of taper, out-of-roundness, or cylinder-
to-piston clearance measured exceeds the specified
limit or if there is any damage on the cylinder wall,
rebore it to use an oversize piston.
CAUTION:
When any of the cylinders needs reboring, all other
cylinders must be bored at the same time, and use
oversize pistons. Do not perform boring on one cylin-
der only, nor use an oversize piston for one cylinder
only.
(2) If the cylinder inner diameter exceeds the limit after
boring and honing, replace the crankcase.
CAUTION:
Immediately after reboring, the cylinder diameter may
differ from its real diameter due to temperature rise.
Thus, pay attention to this when measuring the cylin-
der diameter.
Limit of cylinder enlarging (boring):
0.5 mm (0.020 in)
3. 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 cylin-
der as instructed in 2. CYLINDER AND PISTON 2-3b
[W5C2]. If any of the clearances is not to specification,
replace the piston or bore the cylinder to use an oversize
piston.
B2M0083
3) Make sure that piston pin can be inserted into the pis-
ton pin hole with a thumb at 20°C (68°F). Replace if defec-
tive.
Standard clearance between piston pin and hole in
piston:
Standard
0.004—0.010 mm (0.0002—0.0004 in)
Limit
0.020 mm (0.0008 in)
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2-3bSERVICE PROCEDURE
5. Cylinder Block

B2M0084A
B2M0420A
4) Check circlip installation groove on the piston for burr.
If necessary, remove burr from the groove so that piston
pin can lightly move.
5) Check piston pin circlip for distortion, cracks and wear.
G2M0172
4. PISTON RING
1) If piston ring is broken, damaged, or worn, or if its ten-
sion is insufficient, or when the piston is replaced, replace
piston ring with a new one of the same size as the piston.
CAUTION:
“R”or“N”is marked on the end of the top and sec-
ond rings. When installing the rings to the piston, face
this mark upward.
G2M0624
The oil ring is a combined ring consisting of two
rails and a spacer in between. When installing, be care-
ful to assemble correctly.
G2M0174
2) Squarely place piston ring and oil ring in cylinder, and
measure the piston ring gap with a thickness gauge.
Unit: mm (in)
Standard Limit
Piston
ring gapTop ring0.20—0.35
(0.0079—0.0138)1.0 (0.039)
Second ring0.37—0.52
(0.0146—0.0205)1.0 (0.039)
Oil ring rail0.20—0.60
(0.0079—0.0236)1.5 (0.059)
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2-3bSERVICE PROCEDURE
5. Cylinder Block

G2M0175
3) Measure the clearance between piston ring and piston
ring groove with a thickness gauge.
CAUTION:
Before measuring the clearance, clean the piston ring
groove and piston ring.
Unit: mm (in)
Standard Limit
Clearance
between piston
ring and piston
ring grooveTop ring0.040—0.080
(0.0016—
0.0031)0.15 (0.0059)
Second ring0.030—0.070
(0.0012—
0.0028)0.15 (0.0059)
5. CONNECTING ROD
1) Replace connecting rod, if the large or small end thrust
surface is damaged.
G2M0196
2) Check for bend or twist using a connecting rod aligner.
Replace 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)


1Thickness gauge


2Connecting rod
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2-3bSERVICE PROCEDURE
5. Cylinder Block

G2M0176
3) Install connecting rod fitted with bearing to crankshaft
and measure the side clearance (thrust clearance).
Replace connecting rod if the side clearance exceeds the
specified limit.
Connecting rod side clearance:
Standard
0.070—0.330 mm (0.0028—0.0130 in)
Limit
0.4 mm (0.016 in)
4) Inspect connecting rod bearing for scar, peeling,
seizure, melting, wear, etc.
5) Measure the oil clearance on individual connecting rod
bearings by means of plastigauge. If any oil clearance is
not within specification, replace the defective bearing with
a new one of standard size or undersize as necessary.
(See the table below.)
Connecting rod oil clearance:
Standard
0.010—0.038 mm (0.0004—0.0015 in)
Limit
0.05 mm (0.0020 in)
Unit: mm (in)
BearingBearing size
(Thickness at center)Outer diameter of
crank pin
Standard1.492—1.501
(0.0587—0.0591)47.984—48.000
(1.8891—1.8898)
0.03 (0.0012)
undersize1.510—1.513
(0.0594—0.0596)47.954—47.970
(1.8879—1.8886)
0.05 (0.0020)
undersize1.520—1.523
(0.0598—0.0600)47.934—47.950
(1.8872—1.8878)
0.25 (0.0098)
undersize1.620—1.623
(0.0638—0.0639)47.734—47.750
(1.8793—1.8799)
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2-3bSERVICE PROCEDURE
5. Cylinder Block

B2M0085
6) Inspect bushing at connecting rod small end, and
replace if worn or damaged. Also measure the piston pin
clearance at the connecting rod small end.
Clearance between piston pin and bushing:
Standard
0—0.022 mm (0—0.0009 in)
Limit
0.030 mm (0.0012 in)
B2M0084A
G2M0177
7) Replacement procedure is as follows.
(1) Remove bushing from connecting rod with ST and
press.
(2) Press bushing with ST after applying oil on the
periphery of bushing.
ST 499037100 CONNECTING ROD BUSHING
REMOVER AND INSTALLER
(3) Make two 3 mm (0.12 in) holes in bushing. Ream
the inside of bushing.
(4) After completion of reaming, clean bushing to
remove chips.
6. CRANKSHAFT AND CRANKSHAFT BEARING
1) Clean crankshaft completely and check for cracks by
means of red lead check etc., and replace if defective.
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2-3bSERVICE PROCEDURE
5. Cylinder Block