Lexus LS400 (2000 year). Service manual - part 90

Z03989

60

°

45

°

1.0 – 1.4 mm

EM6331

EM0988

Deviation

EM0801

EM0281

EM–48

–

ENGINE MECHANICAL

CYLINDER HEAD

1230

If the seating is too low on the valve face, use 60

°

and 45

°

 cutters to correct the seat.

(d)

Hand–lap the valve and valve seat with an abrasive com-
pound.

(e)

After hand–lapping, clean the valve and valve seat.

12.

INSPECT VALVE SPRINGS

(a)

Using a steel square, measure the deviation of the valve
spring.
Maximum deviation: 2.0 mm (0.079 in.)

If the deviation is greater than maximum, replace the valve
spring.

(b)

Using vernier calipers, measure the free length of the
valve spring.
Free length: 54.05 – 54.15 mm (2.1279 – 2.1319 in.)

If the free length is not as specified, replace the valve spring.

(c)

Using a spring tester, measure the tension of the valve
spring at the specified installed length.
Installed tension:
204 – 226 N (20.8 – 23.0 kgf, 45.9 – 50.7 lbf)
at 35.0 mm (1.378 in.)

If the installed tension is not as specified, replace the valve
spring.

A03202

EM2011

EM2538

A02880

A03222

A

A

–

ENGINE MECHANICAL

CYLINDER HEAD

EM–49

1231

13.

INSPECT CAMSHAFT FOR RUNOUT

(a)

Place the camshaft on V–blocks.

(b)

Using a dial indicator, measure the circle runout at the
center journal.
Maximum circle runout: 0.08 mm (0.0031 in.)

If the circle runout is greater than maximum, replace the cam-
shaft.

14.

INSPECT CAM LOBES

Using a micrometer, measure the cam lobe height.

Standard cam lobe height:

Intake

42.610 – 42.710 mm (1.6776 – 1.6815 in.)

Exhaust

42.630 – 42.730 mm (1.6783 – 1.6823 in.)

Minimum cam lobe height:

Intake

42.46 mm (1.6717 in.)

Exhaust

42.48 mm (1.6724 in.)

If the cam lobe height is less than minimum, replace the cam-
shaft.

15.

INSPECT CAMSHAFT JOURNALS

Using a micrometer, measure the journal diameter.

Journal diameter:

Intake camshaft (A)

30.984 – 31.000 mm (1.2198 – 1.2205 in.)

Others

26.954 – 26.970 mm (1.0612 – 1.0618 in.)

If the journal diameter is not as specified, check the oil clear-
ance.

A03217

Knock Pin

Red Painted
Mark

Green
Painted
Mark

A03203

EM3322

A03216

LH Cylinder Head

RH Cylinder Head

Front

Mark
A or B

A03204

Plastigage

EM–50

–

ENGINE MECHANICAL

CYLINDER HEAD

1232

16.

INSPECT CAMSHAFT TIMING TUBE JOURNALS

HINT:
There are 2 size of the camshaft timing tube journal diameter,
green and red painted mark accordingly. The mark is painted
on the face of the camshaft timing tube.

Using a micrometer, measure the journal diameter.

Journal diameter:

Green painted mark

39.958 – 39.964 mm (1.5731 – 1.5734 in.)

Red painted mark

39.964 – 39.970 mm (1.5734 – 1.5736 in.)

If the journal diameter is not as specified, check the oil clear-
ance.

17.

INSPECT CAMSHAFT GEAR SPRING

Using vernier calipers, measure the free distance between the
spring ends.

Free distance: 18.2 – 18.8 mm (0.712 – 0.740 in.)

If the free distance is not as specified, replace the gear spring.
18.

INSPECT CAMSHAFT BEARINGS

Check that bearings for flaking and scoring.
If the bearings are damaged, replace the bearing caps and cyl-
inder head as a set.

19.

INSPECT CAMSHAFT TIMING TUBE AND CAMSHAFT
JOURNAL OIL CLEARANCE

HINT:
There are 2 size of the camshaft timing tube journal oil clear-
ance, Marked ”A” and ”B” accordingly. The mark is stamped on
the top of the cylinder heads.
(a)

Install the camshaft timing tube. (See page 

EM–58

)

(b)

Clean the bearing caps and camshaft journals.

(c)

Place the camshafts on the cylinder head.

(d)

Lay a strip of Plastigage across each of the camshaft jour-
nals.

A03205

A03206

A03207

–

ENGINE MECHANICAL

CYLINDER HEAD

EM–51

1233

(e)

Install the bearing caps. (See page 

EM–58

)

Torque: 16 N·m (160 kgf·cm, 12 ft·lbf)

NOTICE:
Do not turn the camshaft.
(f)

Remove the bearing caps.

(g)

Measure the Plastigage at its widest point.
Standard Oil clearance:

Camshaft timing tube

Mark ”A”

0.036 – 0.050 mm (0.0014 – 0.0020 in.)

Camshaft timing tube

Mark ”B”

0.038 – 0.052 mm (0.0015 – 0.0021 in.)

Others

0.030 – 0.067 mm (0.0012 – 0.0026 in.)

Maximum oil clearance:

Camshaft timing tube

0.085 mm (0.0033 in.)

Others

0.10 mm (0.0039 in.)

If the oil clearance is greater than maximum, replace the cam-
shaft. If necessary, replace the bearing caps and cylinder head
as a set.
(h)

Completely remove the plastigage.

(i)

Remove the camshafts.

(j)

Remove the camshaft timing tube.

20.

IF NECESSARY REPLACE CAMSHAFT TIMING TUBE

Select a camshaft timing tube according to mark on the cylinder
head.

Cylinder Head

Camshaft timing tube

Mark ”A”

Green painted mark

Mark ”B”

Red painted mark

21.

INSPECT CAMSHAFT THRUST CLEARANCE

(a)

Install the camshaft timing tube. (See page 

EM–58

)

(b)

Install the camshaft. (See page 

EM–58

)

(c)

Using a dial indicator, measure the thrust clearance while
moving the camshaft back and forth.
Standard thrust clearance:

Intake

0.060 – 0.100 mm (0.0024 – 0.0039 in.)

Exhaust

0.040 – 0.090 mm (0.0016 – 0.0035 in.)

Maximum thrust clearance:

Intake

0.13 mm (0.0051 in.)

Exhaust

0.12 mm (0.0047 in.)