Lexus LS400 (2000 year). Manual — part 75

A02069

: Mark 1, 2,or 3

Front

No.2 No.4 No.6 No.8

No.1 No.3 No.5 No.7

Z04009

1

2

1

2

B

C

A

Thrust
Direction

Axial
Direction

10 mm
(0.39 in.)

10 mm
(0.39 in.)

Front

EM6412

Ridge
Reamer

EM6347

–

ENGINE MECHANICAL

CYLINDER BLOCK

EM–101

1283

5.

INSPECT CYLINDER BORE DIAMETER

HINT:
There are 3 sizes of the standard cylinder bore diameter,
marked ”1”, ”2” and ”3” accordingly. The mark 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.

6.

REMOVE CYLINDER RIDGE

If the wear is less than 0.2 mm (0.008 in.), using a ridge reamer,
grind the top of the cylinder.

7.

INSPECT MAIN BEARING CAP BOLTS

Using vernier calipers, measure the tension portion diameter of
the bolt.

Diameter:

Standard

7.500 – 7.600 mm (0.2953 – 0.2992 in.)

Minimum

7.20 mm (0.2835 in.)

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

A02071

A02072

A02073

A02074
A02075

A02076

26.5 mm

LH Piston

RH Piston

Mark 1, 2, or 3

Mark 1, 2, or 3

EM–102

–

ENGINE MECHANICAL

CYLINDER BLOCK

1284

8.

CLEAN PISTON

(a)

Using a gasket scraper, remove the carbon from the pis-
ton top.

(b)

Using a groove cleaning tool or broken ring, clean the pis-
ton ring grooves.

(c)

Using solvent and a brush, thoroughly clean the piston.

NOTICE:
Do not use a wire brush.

9.

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 right
angles to the piston pin center line, 26.5 mm (1.04 in.)
from the piston head.
Piston diameter:

Mark ”1”

87.406 – 87.416 mm (3.4411 – 3.4416 in.)

Mark ”2”

87.416 – 87.426 mm (3.4416 – 3.4420 in.)

Mark ”3”

87.426 – 87.436 mm (3.4420 – 3.4424 in.)

(b)

Measure the cylinder bore diameter in the thrust direc-
tions. (See step 5 above)

(c)

Subtract the piston diameter measurement from the cylin-
der bore diameter measurement.
Oil clearance:

Standard

0.084 – 0.104 mm (0.0033 – 0.0041 in.)

Maximum

0.124 mm (0.0049 in.)

A02069
A02077

A02075

A02078

Cylinder Block

: Mark 1, 2,or 3

Front

No.2 No.4 No.6 No.8

No.1 No.3 No.5 No.7

LH Piston

RH Piston

Mark
1, 2, or 3

Mark
1, 2, or 3

A02079

A02081

105 mm

–

ENGINE MECHANICAL

CYLINDER BLOCK

EM–103

1285

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”.

10.

INSPECT PISTON RING GROOVE CLEARANCE

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

Ring groove clearance:

No.1

0.020 – 0.070 mm (0.0008 – 0.0028 in.)

No.2

0.010 – 0.050 mm (0.0004 – 0.0020 in.)

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

11.

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 bot-
tom of the ring travel, 105 mm (4.13 in.) from the top of the
cylinder block.

EM7639

A02080

60

°

C

Z14454

Z14455

EM–104

–

ENGINE MECHANICAL

CYLINDER BLOCK

1286

(c)

Using a feeler gauge, measure the end gap.
Standard end gap:

No.1

0.250 – 0.450 mm (0.0098 – 0.0177 in.)

No.2

0.500 – 0.700 mm (0.0197 – 0.0276 in.)

Oil (Side rail)

0.150 – 0.500 mm (0.0059 – 0.0197 in.)

Maximum end gap:

No.1

1.05 mm (0.0413 in.)

No.2

1.30 mm (0.0512 in.)

Oil (Side rail)

1.10 mm (0.0433 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.

12.

INSPECT PISTON PIN FIT

At 60

°

C (140

°

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

the piston pin hole with your thumb.

13.

INSPECT CONNECTING ROD ALIGNMENT

Using a rod aligner and feeler gauge, 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 as-
sembly.

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 as-
sembly.