Lexus SC300 / Lexus SC400. Manual — part 386

7.

IF NECESSARY, REPLACE MAIN BEARING CAP STUD
BOLTS

(a) Using the 2 main bearing cap nuts, remove the stud bolt.

(b) Apply a light coat of engine oil on the threads and under

flange of new stud bolts.

(c) Using the 2 main bearing cap nuts, install the stud bolt.

Torque: 15 N

⋅

m (150 kgf

⋅

cm, 11 ft

⋅

lbf)

HINT: Stud bolts come in lengths of 90.0 mm (3.543 in.) and
101.5 mm (3.996 in.). Install the 101.5 mm (3.996 in.) bolts
in inside positions. Install the 90.0 mm (3.543 in.) bolts in out-
side positions.

PISTON AND CONNECTING ROD
DISASSEMBLY

EG0BV–06

1.

CHECK FIT BETWEEN PISTON AND PISTON PIN
Try to move the piston back and forth on the piston pin.
If any movement is felt, replace the piston and pin as a set.

2. REMOVE

PISTON

RINGS

(a) Using a piston ring expander, remove the 2 compression

rings.

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EG–167

(b) Remove the 2 side rails and oil ring by hand.

HINT: Arrange the piston rings in correct order only.

3.

DISCONNECT CONNECTING ROD FROM PISTON

(a) Using a small screwdriver, pry out the 2 snap rings.

(b) Gradually heat the piston to approx. 60

C (140

F).

(c) Using a plastic–faced hammer and brass bar, lightly tap out

the piston pin and pin and remove the connecting rod.

EG–168

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ENGINE MECHANICAL

HINT:

•

The piston and pin are a matched set.

•

Arrange the pistons, pins, rings, connecting rods and
bearings in correct order.

PISTON AND CONNECTING ROD
INSPECTION

EG1KY–02

1. CLEAN

PISTON

(a) Using a gasket scraper, remove the carbon from the piston

top.

(b) Using a groove cleaning tool or broken ring, clean the piston

ring grooves.

(c) Using solvent and a brush, thoroughly clean the piston.

NOTICE: Do not use a wire brush.

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EG–169

2. INSPECT

PISTON

A.

Inspect piston oil clearance
HINT: There are 3 sizes of the standard piston diameter,
marked “1”, “2” and “3” accordingly. The mark is stamped on
the piston top.

(a) Using a micrometer, measure the piston diameter at ring

angles to the piston pin center line, 49 mm (1.93 in.) from the
piston head.

Piston diameter:

Mark “1”

87.470 – 87.480 mm (3.4437 – 3.4441 in.)

Mark “2”

87.480 – 86.490 mm (3.4441 – 3.4445 in.)

Mark “3”

87.490 – 87.500 mm (3.4445 – 3.4449 in.)

(b) Measure the cylinder bore diameter in the thrust directions.

(See step 4 on page EG–xxx)

(c) Subtract the piston diameter measurement from the cylinder

bore diameter measurement.

Standard oil clearance:

0.020 – 0.040 mm (0.0008 – 0.0016 in.)

Maximum oil clearance:

0.06 mm (0.0024 in.)

If the oil clearance is greater than maximum, replace all the
8 pistons. If necessary, replace the cylinder block.
HINT (Use new cylinder block):

•

Use a piston with the same number mark as the cylinder
diameter marked on the cylinder block.

•

The shape of the piston varies for the RH and LH banks.
The RH piston is marked with “R”, the LH piston with “L”.

EG–170

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