Lexus RX300 (MCU15). Manual — part 454

EM0KN–02

P12499

Z09222

P12498

EM–100

–

ENGINE MECHANICAL

CYLINDER BLOCK

LEXUS RX300 (RM785E)

INSPECTION

1.

REMOVE GASKET MATERIAL

Using a gasket scraper, remove all the gasket material from the
top surface of the cylinder block.
2.

CLEAN CYLINDER BLOCK

Using a soft brush and solvent, thoroughly clean the cylinder
block.
NOTICE:
If the cylinder is washed at high temperatures, the cylinder
liner sticks out beyond the cylinder block, so always wash
the cylinder block at a temperature of 45°C (113°F) or less.

3.

INSPECT TOP SURFACE OF CYLINDER BLOCK FOR
FLATNESS

Using a precision straight edge and feeler gauge, measure the
surface contacting the cylinder head gasket for warpage.

Maximum warpage: 0.07 mm (0.0028 in.)

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

4.

INSPECT CYLINDER FOR VERTICAL SCRATCHES

Visually check the cylinder for vertical scratches.
If deep scratches are present, replace the cylinder block.

Z09220

Front

1

2

1

2

Thrust
Direction

Axial
Direction

A

B

C

10 mm
(0.39 in.)

10 mm
(0.39 in.)

A05258

P12497

P12507

–

ENGINE MECHANICAL

CYLINDER BLOCK

EM–101

LEXUS RX300 (RM785E)

5.

INSPECT CYLINDER BORE DIAMETER

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

Standard diameter:
87.500 – 87.512 mm (3.4449 – 3.4453 in.)
Maximum diameter: 87.52 mm (3.4457 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 12 POINTED HEAD MAIN BEARING CAP
BOLTS

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

Standard diameter:
7.500 – 7.600 mm (0.2953 – 0.2992 in.)
Minimum diameter: 7.20 mm (0.2835 in.)

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

8.

CLEAN PISTON

(a)

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

P12491

P12505

A05259

RH piston:

23.2 mm

LH piston:

P12504

EM–102

–

ENGINE MECHANICAL

CYLINDER BLOCK

LEXUS RX300 (RM785E)

(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

(a)

Using a micrometer, measure the piston diameter at right
angles to the piston pin center line, 23.2 mm (0.913 in.)
from the piston head.
Piston diameter:
87.406 – 87.416 mm (3.4412 – 3.4416 in.)

(b)

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

(c)

Subtract the piston diameter measurement from the cylin-
der bore diameter measurement.
Standard oil clearance:
0.084 – 0.106 mm (0.0033 – 0.0042 in.)
Maximum oil clearance: 0.13 mm (0.0051 in.)

If the oil clearance is greater than maximum, replace all the 6
pistons. If necessary, replace the cylinder block.
HINT:
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 right and the wall of the ring groove.

Ring groove clearance:
No. 1: 0.020 – 0.070 mm (0.0008 – 0.0028 in.)
No. 2: 0.020 – 0.060 mm (0.0008 – 0.0024 in.)

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

P12583

105 mm

EM7639

P12506

Z04012

–

ENGINE MECHANICAL

CYLINDER BLOCK

EM–103

LEXUS RX300 (RM785E)

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.

(c)

Using a feeler gauge, measure the end gap.
Standard end gap:
No. 1: 0.25 – 0.35 mm (0.0098 – 0.0138 in.)
No. 2: 0.35 – 0.45 mm (0.0138 – 0.0177 in.)
Oil (Side rail): 0.15 – 0.40 mm (0.0059 – 0.0157 in.)
Maximum end gap:
No. 1: 0.95 mm (0.0374 in.)
No. 2: 1.05 mm (0.0413 in.)
Oil (Side rail): 1.00 mm (0.0394 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.

S

Check for out–of–alignment.

Maximum out–of–alignment:
0.05 mm (0.0020 in.) per 100 mm (3.94 in.)

If out–of–alignment is greater than maximum, replace the con-
necting rod assembly.