Lexus SC300 / Lexus SC400. Manual — part 461

B. Inspect piston ring groove clearance

Using a feeler gauge, measure the clearance between new
piston ring and the wall of the piston ring groove.

Ring groove clearance:

No. 1

0.011–0.07 mm (0.0004–0.0028 in.)

No. 2

0.03–0.07 mm (0.0012–0.0028 in.)

If the clearance is not as specified, replace the piston.

C. Inspect piston ring end gap

(a) Insert the piston ring into the cylinder bore.
(b) Using a piston, push the piston ring a little beyond the

bottom of the ring travel, 130 mm (5.12 in.) from the top
of the cylinder block.

(c) Using a feeler gauge, measure the ring end gap.

Standard ring end gap:

No. 1

0.30–0.47 mm

(0.0120–0.0188 in.)

No. 2

0.35–0.52 mm

(0.0138–0.0208 in.)

Oil (Side rail)

0.13–0.45 mm

(0.0051–0.0177 in.)

Maximum ring end gap:

No. 1

1.07 mm (0.0428 in.)

No. 2

1.12 mm (0.0448 in.)

Oil (Side rail)

1.05 mm (0.0420 in.)

If the end gap is greater than maximum, replace the piston
ring. If the end gap is greater than maximum, even with a new
piston ring, replace the cylinder block.

D. Inspect piston pin fit

At 80

°

C (176

°

F), you should be able to push the piston pin

into the piston pin hole with your thumb.
If the piston pin can be pushed in at room temperature, the
piston and the piston pin must be replaced as a set.

EM–88

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ENGINE MECHANICAL

Cylinder Block

3.

INSPECT CONNECTING ROD

A.

Inspect connecting rod alignment
Using a feeler gauge and rod aligner, check the connecting
rod alignment.

•

Check for bend.

Maximum bend:

0.05 mm (0.0020 in.) per 100 mm (3.94 in.)

If bend is greater than maximum, replace the connecting rod
assembly.

•

Check for twist.

Maximum twist:

0.15 mm (0.0059 in.) per 100 mm (3.94 in.)

If twist is greater than maximum, replace the connecting rod
assembly.

B.

Inspect piston pin oil clearance
(a) Using a caliper gauge, measure the inside diameter of

the connecting rod bushing.

Bushing inside diameter: 22.005–22.014 mm

(0.8663–0.8667 in.)

(b) Using a micrometer, measure the piston pin diameter.

Piston pin diameter:

21.997–22.006 mm

(0.8660–0.8664 in.)

(c) Subtract the piston pin diameter measurement from the

bushing inside diameter measurement.

Standard oil clearance:

0.005–0.011 mm

(0.0002–0.0004 in.)

Maximum oil clearance: 0.05 mm (0.0020 in.)

If the oil clearance is greater than maximum, replace the
bushing. If necessary, replace the piston and piston pin as a
set.

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ENGINE MECHANICAL

Cylinder Block

EM–89

C. If necessary, replace connecting rod bushing

(a) Using SST and a press, press out the bushing.
SST 09222–30010

(b) Align the oil holes of a new bushing and the connecting

rod.

(c) Using SST and a press, press in the bushing.
SST 09222–30010

(d) Using a pin hole grinder, bore the bushing to obtain the

standard specified clearance (see step B above)
between the bushing and piston pin.

(e) Check the piston pin fit at room temperature.
Coat the piston pin with engine oil, and push it into the con-
necting rod with your thumb.

D. Inspect connecting rod bolts

Using vernier calipers, measure the minimum diameter of the
compressed bolt at the measuring point.

Standard diameter:

8.2–8.3 mm

(0.325–0.327 in.)

Minimum diameter:

8.0 mm (0.315 in.)

If the diameter is less than minimum, replace the connecting
rod bolt.

EM–90

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ENGINE MECHANICAL

Cylinder Block

INSPECTION OF CRANKSHAFT

1.

INSPECT CRANKSHAFT FOR RUNOUT
(a) Place the crankshaft on V–blocks.
(b) Using a dial indicator, measure the circle runout at the

center journal.

Maximum circle runout:

0.06 mm (0.0024 in.)

If the circle runout is greater than maximum, replace the
crankshaft.

2.

INSPECT MAIN JOURNALS AND CRANK PINS
(a) Using a micrometer, measure the diameter of each main

journal and crank pin.

Main journal diameter:

61.984–62.000 mm

(2.4403–2.4409 in.)

Crank pin diameter:

51.982–52.000 mm

(2.0465–2.0472 in.)

If the diameter is not as specified, check the oil clearance
(See page EM–77 or EM–80).
(b) Check each main journal and crank pin for taper and

out–of–round as shown.

Maximum taper and out–of round:

0.02 mm

(0.0008 in.)

If the taper or out–of–round is greater than maximum, re-
place the crankshaft.

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ENGINE MECHANICAL

Cylinder Block

EM–91