Lexus SC300 / Lexus SC400. Manual - part 586

3. 

INSPECT CYLINDER FOR VERTICAL SCRATCHES
Visually check the cylinder for vertical scratches.
If deep scratches are present, replace the cylinder block.

4. 

INSPECT CYLINDER BORE DIAMETER
HINT: There are three sizes of the standard cylinder bore di-
ameter, marked ”1”, ”2” and ”3” accordingly. The marked is
stamped on the top of the cylinder block.

Using a cylinder gauge, measure the cylinder bore diameter
at positions A, B and C in the thrust and axial directions.

Standard diameter:

Mark ”1” 87.500–87.510 mm

(3.4449–3.4453 in.)

Mark ”2” 87.510–87.520 mm

(3.4453–3.4457 in.)

Mark ”3” 87.520–87.530 mm

(3.4457–3.4461 in.)

Maximum diameter: 87.73 mm (3.4539 in.)

If the diameter is greater than maximum, replace the cylinder
block.

5. 

REMOVE CYLINDER RIDGE
If the wear is less than 0.2 mm (0.008 in.), using a ridge ream-
er, grind the top of the cylinder.

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ENGINE MECHANICAL

Cylinder Block

EM–143

6. 

INSPECT MAIN BEARING CAP STUD BOLTS
Using a vernier caliper, measure the tension portion diameter
of the stud bolt.

Standard diameter: 7.500–7.600 mm

(0.2953–0.2992 in.)

Minimum diameter: 7.40 mm (0.2913 in.)

If the diameter is less than minimum, replace the stud bolt.

7. 

IF NECESSARY, REPLACE MAIN BEARING CAP STUD
BOLTS
(a)  Using the two main bearing cap nuts, remove the stud

bolt.

(b) Apply 

a 

light coat of engine oil on the threads and under

the flange of the stud bolt.

(c)  Using the two main bearing cap nuts, install and torque

the stud bolt.

Torque: 10 N

⋅

m (100 kgf

⋅

cm, 7 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.

DISASSEMBLY OF PISTON AND
CONNECTING ROD ASSEMBLIES

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.

EM–144

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ENGINE MECHANICAL

Cylinder Block

2. REMOVE 

PISTON 

RINGS

(a)  Using a piston ring expander, remove  the  two

compression rings.

(b) Remove 

the two side rails and oil ring expander 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 two snap rings.

(b)  Gradually heat the piston to approx. 60

°

C (140

°

F).

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

out the piston pin and remove the connecting rod.

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ENGINE MECHANICAL

Cylinder Block

EM–145

HINT:

•

The piston and pin are a matched set.

•

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

INSPECTION OF PISTON AND
CONNECTING ROD ASSEMBLIES

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.

EM–146

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ENGINE MECHANICAL

Cylinder Block