Lexus SC300 / Lexus SC400. Manual - part 460

INSPECTION AND REPAIR OF
CYLINDER BLOCK

1. 

CLEAN CYLINDER BLOCK

A.

 Remove gasket material
Using a gasket scraper, remove all the gasket material from
the cylinder block surface.

B.

 Clean cylinder block
Using a soft brush and solvent, thoroughly clean the cylinder
block.

2. 

INSPECT CYLINDER BLOCK SURFACE FOR FLATNESS
Using precision straight edge and feeler gauge, measure the
top surfaces of the cylinder block for warpage.

Maximum warpage: 

0.07 mm (0.0028 in.)

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

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
(a)  Using a cylinder gauge, measure the cylinder bore

diameter at positions A, B and C in the thrust and axial
directions.

Standard diameter: 

86.000–86.013 mm

(3.3858–3.3863 in.)

Maximum diameter: 

86.02 mm (3.3866 in.)

If the diameter is greater than maximum, replace the cylinder
block.
(b)  Difference between measurements A, B and C is

greater than taper limit.

Taper limit: 

0.01 mm (0.0004 in.)

(c)  Difference between the thrust and axial measurements

is greater than out–of–round limit.

Out–of–round limit: 

0.02 mm (0.0008 in.)

EM–84

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ENGINE MECHANICAL

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.

6. 

INSPECT MAIN BEARING CAP BOLTS
Using vernier calipers, measure the minimum diameter of the
compressed thread at the measuring point.

Standard diameter: 

9.96–9.97 mm

(0.3921–0.3925 in.)

Minimum diameter: 

9.7 mm (0.3819 in.)

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

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.

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.

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ENGINE MECHANICAL

Cylinder Block

EM–85

3. 

DISCONNECT CONNECTING ROD FROM PISTON
(a)  Using a small screwdriver, remove the snap rings.

(b)  Gradually heat the piston to about 80

C (176

F).

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

out the piston pin and remove the connecting rod.

HINT:

•

The piston and pin are a matched set.

•

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

EM–86

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ENGINE MECHANICAL

Cylinder Block

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.

2. INSPECT 

PISTON

A.

 Inspect piston oil clearance
(a)  Using a micrometer, measure the piston diameter at

right angles to the piston pin center line, 34 mm (1.34 in.)
from the piston head.

Piston diameter:

85.935–85.945 mm

(3.3833–3.3837 in.)

(b) Measure the cylinder bore diameter in the thrust

directions. (See step 4 on page EM–84)

(c)  Subtract the piston diameter measurement from the

cylinder bore diameter measurement.

Standard oil clearance: 

0.055–0.078 mm

(0.0022–0.0031 in.)

Maximum oil clearance: 

0.10 mm (0.0039 in.)

If the oil clearance is greater than maximum, replace all the
six pistons. If necessary, replace the cylinder block.

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ENGINE MECHANICAL

Cylinder Block

EM–87