2000 LEXUS GS400 Service Repair Manual

EM0DC±03
A02682
A02683
A02705
A02706
P02072
EM±40
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
1394 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. CLEAN TOP SURFACES OF PISTONS AND
CYLINDER BLOCK
(a) Turn the crankshaft, and bring each piston to top dead
center (TDC). Using a gasket scraper, remove all the car-
bon from the piston top surface.
(b) Using a gasket scraper, remove all the gasket material
from the top surface of the cylinder block.
(c) Using compressed air, blow carbon and oil from the bolt
holes.
CAUTION:
Protect your eyes when using high ± pressure compressed
air.
2. CLEAN CYLINDER HEAD
(a) Remove the gasket material.
Using a gasket scraper, remove all the gasket material
from the cylinder block surface.
NOTICE:
Be careful not to scratch the cylinder block contact sur-
face.
(b) Clean the combustion chambers.
Using a wire brush, remove all the carbon from the com-
bustion chambers.
NOTICE:
Be careful not to scratch the cylinder block contact sur-
face.
(c) Clean the valve guide bushings.
Using a valve guide bushing brush and solvent, clean all
the guide bushings.

A02707
A02711P02145
P02135
P02144
A03796
A02708
EM0580
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
EM±41
1395 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(d) Clean the cylinder head.
Using a soft brush and solvent, thoroughly clean the cylin-
der head.
3. INSPECT CYLINDER HEAD
(a) Inspect for the flatness.
Using precision straight edge and feeler gauge, measure
the surfaces contacting the cylinder block, intake and ex-
haust manifolds for warpage.
Maximum warpage: 0.10 mm (0.0039 in.)
If warpage is greater than maximum, replace the cylinder head.
(b) Inspect for the cranks.
Using a dye penetrant, check the combustion chamber,
intake ports, exhaust ports and cylinder block surface for
cracks.
If cracked, replace the cylinder head.
4. CLEAN VALVES
(a) Using a gasket scraper, chip off any carbon from the valve
head.
(b) Using a wire brush, thoroughly clean the valve.

Z02413
Z00052
Z00054
44.5°
EM0181
Margin Thickness EM±42
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
1396 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
5. INSPECT VALVE STEMS AND GUIDE BUSHINGS
(a) Using a caliper gauge, measure the inside diameter of the
guide bushing.
Bushing inside diameter:
6.010 ± 6.030 mm (0.2366 ± 0.2374 in.)
(b) Using a micrometer, measure the diameter of the valve
stem.
Valve stem diameter:
Intake5.970 ± 5.985 mm (0.2350 ± 0.2356 in.)
Exhaust5.965 ± 5.980 mm (0.2348 ± 0.2354 in.)
(c) Subtract the valve stem diameter measurement from the
guide bushing inside diameter measurement.
Standard oil clearance:
Intake0.025 ± 0.060 mm (0.0010 ± 0.0024 in.)
Exhaust0.030 ± 0.065 mm (0.0012 ± 0.0026 in.)
Maximum oil clearance:
Intake0.08 mm (0.0031 in.)
Exhaust0.10 mm (0.0039 in.)
If the clearance is greater than maximum, replace the valve and
guide bushing. (See page EM±48)
6. INSPECT AND GRIND VALVES
(a) Grind the valve enough to remove pits and carbon.
(b) Check that the valve is ground to the correct valve face
angle.
Valve face angle: 44.5°
(c) Check the valve head margin thickness.
Standard margin thickness:
0.8 ± 1.2 mm (0.031 ± 0.047 in.)
Minimum margin thickness:
0.5 mm (0.020 in.)
If the margin thickness is less than minimum, replace the valve.

EM2534
Overall
Length
EM0255
A02709
45° Carbide Cutter
Z00373
Width
P03966
Width 45°
15°
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
EM±43
1397 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(d) Check the valve overall length.
Standard overall length:
Intake98.29 ± 98.79 mm (3.8697 ± 3.8894 in.)
Exhaust98.84 ± 99.34 mm (3.8913 ± 3.9110 in.)
Minimum overall length:
Intake98.19 mm (3.8657 in.)
Exhaust98.74 mm (3.8874 in.)
If the overall length is less than minimum, replace the valve.
(e) Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, resurface the tip with a grinder or
replace the valve.
NOTICE:
Do not grind off more than the minimum overall length.
7. INSPECT AND CLEAN VALVE SEATS
(a) Using a 45° carbide cutter, resurface the valve seats.
Remove only enough metal to clean the seats.
(b) Check the valve seating position.
Apply a thin coat of Prussian blue (or white lead) to the
valve face. Lightly press the valve against the seat. Do not
rotate the valve.
(c) Check the valve face and seat for the following:

If blue appears 360° around the face, the valve is
concentric. If not, replace the valve.

If blue appears 360° around the valve seat, the
guide and face are concentric. If not, resurface the
seat.

Check that the seat contact is in the middle of the
valve face with the following width:
If not, correct the valve seats as follows:
Intake1.0 ± 1.4 mm (0.039 ± 0.055 in.)
Exhaust1.2 ± 1.6 mm (0.047 ± 0.063 in.)
(1) If the seating is too high on the valve face, use 15°
and 45° cutters to correct the seat.

Z02456Width 75°
45°
A02710
Z02457
Deviation
EM0801
EM0281
EM±44
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
1398 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(2) If the seating is too low on the valve face, use 75°
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.
8. INSPECT VALVE SPRINGS
(a) Using a steel square, measure the deviation of the valve
spring.
Maximum deviation: 2.0 mm (0.079 in.)
If deviation is greater than maximum, replace the valve spring.
(b) Using vernier calipers, measure the free length of the
valve spring.
Free length:
Pink painted mark43.71 mm (1.7209 in.)
Yellow painted mark44.10 mm (1.7362 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:
186.2 ± 205.8 N (19.0 ± 21.0 kgf, 41.9 ± 46.3 lbf)
at 34.5 mm (1.358 in.)
If the installed tension is not as specified, replace the valve
spring.

A02820
EM2011
EM2538
A02817
Plastigage
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
EM±45
1399 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
9. INSPECT CAMSHAFTS 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.
10. INSPECT CAM LOBES
Using a micrometer, measure the cam lobe height.
Standard cam lobe height:
Intake44.310 ± 44.360 mm (1.7445 ± 1.7465 in.)
Exhaust44.250 ± 44.350 mm (1.7421 ± 1.7461 in.)
Minimum cam lobe height:
Intake44.16 mm (1.7386 in.)
Exhaust44.10 mm (1.7362 in.)
If the cam lobe height is less than minimum, replace the cam-
shaft.
11. INSPECT CAMSHAFT JOURNALS
Using a micrometer, measure the journal diameter.
Journal diameter:
28.949 ± 28.965 mm (1.1397 ± 1.1404 in.)
If the journal diameter is not as specified, check the oil clear-
ance.
12. INSPECT CAMSHAFT BEARING
Check the bearings for flaking and scoring.
If the bearings are damaged, replace the bearing caps and cyl-
inder head as a set.
13. INSPECT CAMSHAFT JOURNAL OIL CLEARANCE
(a) Clean the bearing caps and camshaft journals.
(b) Place the camshafts on the cylinder head.
(c) Lay a strip of Plastigage across each of the camshaft jour-
nals.
(d) Install the bearing caps. (See page EM±52)
Torque: 20 N´m (200 kgf´cm, 14 ft´lbf)
NOTICE:
Do not turn the camshaft.
(e) Remove the bearing caps.

A02718
A02815
A02688
EM±46
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
1400 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(f) Measure the Plastigage at its widest point.
Standard oil clearance:
0.035 ± 0.072 mm (0.0014 ± 0.0028 in.)
Maximum oil clearance:
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.
(g) Completely remove the Plastigage.
14. INSPECT CAMSHAFT THRUST CLEARANCE
(a) Install the camshafts. (See page EM±52)
(b) Using a dial indicator, measure the thrust clearance while
moving the camshaft back and forth.
Standard thrust clearance:
0.080 ± 0.190 mm (0.0031 ± 0.0075 in.)
Maximum thrust clearance:
0.30 mm (0.0118 in.)
If the thrust clearance is greater than maximum, replace the
camshaft. If necessary, replace the bearing caps and cylinder
head as a set.
15. INSPECT VALVE LIFTERS AND LIFTER BORES
(a) Using a caliper gauge, measure the lifter bore diameter
of the cylinder head.
Lifter bore diameter:
31.000 ± 31.016 mm (1.2205 ± 1.2211 in.)
(b) Using a micrometer, measure the lifter diameter.
Lifter diameter:
30.966 ± 30.976 mm (1.2191 ± 1.2195 in.)
(c) Subtract the lifter diameter measurement from the lifter
bore diameter measurement.
Standard oil clearance:
0.024 ± 0.050 mm (0.0009 ± 0.0020 in.)
Maximum oil clearance:
0.07 mm (0.0028 in.)
If the oil clearance is greater than maximum, replace the lifter.
If necessary, replace the cylinder head.

A02830
A02829
A02831
A02828
About
50 mm
Compressed
Thread
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
EM±47
1401 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
16. INSPECT AIR INTAKE CHAMBER
Using a precision straight edge and feeler gauge, measure the
surfaces contacting the intake manifold for warpage.
Maximum warpage: 0.15 mm (0.0059 in.)
If warpage is greater than maximum, replace the chamber.
17. INSPECT INTAKE MANIFOLD
Using a precision straight edge and feeler gauge, measure the
surfaces contacting the cylinder head and air intake chamber
for warpage.
Maximum warpage: 0.15 mm (0.0059 in.)
If warpage is greater than maximum, replace the manifold.
18. INSPECT EXHAUST MANIFOLD
Using a precision straight edge and feeler gauge, measure the
surfaces contacting the cylinder head for warpage.
Maximum warpage: 0.50 mm (0.0196 in.)
If warpage is greater than maximum, replace the manifold.
19. INSPECT CYLINDER HEAD BOLTS
Using a vernier caliper, measure the thread outside diameter of
the bolt.
Standard outside diameter:
10.8 ± 11.0 mm (0.425 ± 0.433 in.)
Minimum outside diameter:
10.7 mm (0.421 in.)
If the diameter is less than minimum, replace the bolt.