Page 2633 of 4323

EM1X1±01
A03194
A03193
EM6323
EM6324
P21861
EM±46
± ENGINE MECHANICALCYLINDER HEAD
2625 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION
1. CLEAN TOP SURFACES OF PISTONS AND CYL-
INDER 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 surface contacting gasket scraper, remove all the
gasket materials from 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. REMOVE GASKET MATERIAL
Using a gasket scraper, remove all the gasket material from the
cylinder block contact surface.
NOTICE:
Be careful not to scratch the surface contacting the cylin-
der block.
3. CLEAN COMBUSTION CHAMBERS
Using a wire brush, remove all the carbon from the combustion
chambers.
NOTICE:
Be careful not to scratch the surface contacting the cylin-
der block.
4. CLEAN VALVE GUIDE BUSHINGS
Using a valve guide bushing brush and solvent, clean all the
guide bushings.
Page 2634 of 4323
EM6325
A05592
EM6327
A21018
50 mm
(1.96 in.) Measuring
Point
± ENGINE MECHANICALCYLINDER HEAD
EM±47
2626 Author: Date:
2005 SEQUOIA (RM1146U)
5. CLEAN CYLINDER HEAD
Using a soft brush and solvent, thoroughly clean the cylinder
head.
6. INSPECT FOR FLATNESS
Using a precision straight edge and feeler gauge, measure the
surfaces contacting the cylinder block and the manifolds for
warpage.
Maximum warpage: 0.10 mm (0.0039 in.)
If warpage is greater than maximum, replace the cylinder head.
7. INSPECT FOR CRACKS
Using a dye penetrate, check the combustion chamber, intake
ports, exhaust ports and cylinder block surface for cracks.
If cracked, replace the cylinder head.
8. INSPECT CYLINDER HEAD BOLT
Using vernier calipers, measure the thread outside diameter of
the cylinder head bolt.
Standard outside diameter:
9.810 to 9.960 mm (0.3862 to 0.3921 in.)
Minimum outside diameter: 9.70 mm (0.3819 in.)
If the diameter is less than minimum, replace the bolt.
Page 2635 of 4323

EM0580
A04087A04091A04236
Z00052
Z00054
44.5° EM±48
± ENGINE MECHANICALCYLINDER HEAD
2627 Author: Date:
2005 SEQUOIA (RM1146U)
9. CLEAN VALVES
(a) Using a gasket scraper, chip off any carbon from the valve
head.
(b) Using a wire brush, thoroughly clean the valve.
10. INSPECT VALVE STEMS AND GUIDE BUSHINGS
(a) Using a caliper gauge, measure the inside diameter of the
guide bushing.
Bushing inside diameter:
5.510 to 5.530 mm (0.2169 to 0.2177 in.)
(b) Using a micrometer, measure the diameter of the valve
stem.
Valve stem diameter:
Intake5.470 to 5.485 mm (0.2154 to 0.2159 in.)
Exhaust5.465 to 5.480 mm (0.2152 to 0.2157 in.)
(c) Subtract the valve stem diameter measurement from the
guide bushing inside diameter measurement.
Standard oil clearance:
Intake0.025 to 0.060 mm (0.0010 to 0.0024 in.)
Exhaust0.030 to 0.065 mm (0.0012 to 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±56)
11. 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°
Page 2636 of 4323

EM0181
Margin Thickness
EM2534
Overall Length
EM0255
EM6330
45° Carbide Cutter
Z00055
Width
± ENGINE MECHANICALCYLINDER HEAD
EM±49
2628 Author: Date:
2005 SEQUOIA (RM1146U)
(c) Check the valve head margin thickness.
Standard margin thickness: 1.0 mm (0.039 in.)
Minimum margin thickness: 0.5 mm (0.020 in.)
If the margin thickness is less than minimum, replace the valve.
(d) Check the valve overall length.
Standard overall length:
Intake95.05 mm (3.7421 in.)
Exhaust95.10 mm (3.7441 in.)
Minimum overall length:
Intake94.55 mm (3.7224 in.)
Exhaust94.60 mm (3.7244 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 minimum.
12. INSPECT AND CLEAN VALVE SEATS
(a) Using a 45° carbide cutter, resurface the valve seats. Re-
move only metal enough to clean the seats.
(b) Check the valve seating position.
Apply a light coat of Prussian blue (or white lead) to the
valve face. Lightly press the valve against the seat. Do not
rotate the valve.
Page 2637 of 4323

Z03988
45°30°
1.0 ± 1.4 mm
Z03989
60°45°
1.0 ± 1.4 mm
EM6331
EM0988
Deviation EM±50
± ENGINE MECHANICALCYLINDER HEAD
2629 Author: Date:
2005 SEQUOIA (RM1146U)
(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:
1.0 to 1.4 mm (0.039 to 0.055 in.)
If not, correct the valve seats as follows:
If the seating is too high on the valve face, use 30°
and 45° cutters to correct the seat.
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.
13. 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.
Page 2638 of 4323

EM0801
EM0281
A05912
EM2011
± ENGINE MECHANICALCYLINDER HEAD
EM±51
2630 Author: Date:
2005 SEQUOIA (RM1146U)
(b) Using vernier calipers, measure the free length of the
valve spring.
Free length: 54.1 mm (2.130 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:
210 to 226 N (21.4 to 23.0 kgf, 47.2 to 50.7 lbf)
at 35.0 mm (1.378 in.)
If the installed tension is not as specified, replace the valve
spring.
14. 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: 0.03 mm (0.0012 in.)
If the circle runout is greater than maximum, replace the cam-
shaft.
15. INSPECT CAM LOBES
Using a micrometer, measure the cam lobe height.
Standard cam lobe height:
Intake42.61 to 42.71 mm (1.6776 to 1.6815 in.)
Exhaust42.63 to 42.73 mm (1.6783 to 1.6823 in.)
Minimum cam lobe height:
Intake42.46 mm (1.6717 in.)
Exhaust42.48 mm (1.6724 in.)
If the cam lobe height is less than minimum, replace the cam-
shaft.
Page 2639 of 4323

A04022
A23346
A23347
Turn
EM3322
A04083
Plastigage
EM±52
± ENGINE MECHANICALCYLINDER HEAD
2631 Author: Date:
2005 SEQUOIA (RM1146U)
16. INSPECT CAMSHAFT JOURNALS
Using a micrometer, measure the journal diameter.
Journal diameter:
26.954 to 26.970 mm (1.0612 to 1.0618 in.)
If the journal diameter is not as specified, check the oil clear-
ance (see step 20).
17. INSPECT CAMSHAFT TIMING TUBE
(a) Using a micrometer, measure the journal diameter.
Journal diameter:
39.955 to 39.964 mm (1.5730 to 1.5734 in.)
If the journal diameter is not as specified, check the oil clear-
ance.
(b) Install the timing tube to the intake camshaft, and check
the timing tube turns smoothly.
If necessary, replace the timing tube and intake camshaft.
18. INSPECT CAMSHAFT GEAR SPRING
Using vernier calipers, measure the free distance between the
spring ends.
Free distance: 18.2 to 18.8 mm (0.717 to 0.740 in.)
If the free distance is not as specified, replace the gear spring.
19. INSPECT CAMSHAFT BEARINGS
Check the bearings for flaking and scoring.
If the bearings are damaged, replace the bearing caps and cyl-
inder head as a set.
20. INSPECT CAMSHAFT JOURNAL OIL CLEARANCE
(a) Install the camshaft timing tube to the intake camshaft
(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.
Page 2640 of 4323

A04099A A
A04084
A23348
± ENGINE MECHANICALCYLINDER HEAD
EM±53
2632 Author: Date:
2005 SEQUOIA (RM1146U)
(e) Install the bearing caps (see page EM±60).
Torque:
7.5 N´m (76 kgf´cm, 66 in.´lbf) for bolt A
16 N´m (160 kgf´cm, 12 ft´lbf) for others
NOTICE:
Do not turn the camshaft.
(f) Remove the bearing caps.
(g) Measure the Plastigage at its widest point.
Standard oil clearance:
Camshaft journal0.030 to 0.071 mm (0.0012 to 0.0028 in.)
Camshaft timing tube
journal
0.036 to 0.057 mm (0.0014 to 0.0022 in.)
Maximum oil clearance:
Camshaft journal0.100 mm (0.0039 in.)
Camshaft timing tube
journal0.075 mm (0.0030 in.)
If the oil clearance is greater than the maximum, replace the
camshaft. 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 from the intake cam-
shaft.
21. INSPECT CAMSHAFT THRUST CLEARANCE
(a) Install the camshaft timing tube to the intake camshaft
(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:
Intake0 to 0.040 mm (0 to 0.0016 in.)
Exhaust0.030 to 0.070 mm (0.0012 to 0.0028 in.)
Maximum thrust clearance:
Intake0.12 mm (0.0047 in.)
Exhaust0.10 mm (0.0039 in.)
If the thrust clearance is greater than the maximum, replace the
camshaft. If necessary, replace the bearing caps and cylinder
head as a set.
(d) Remove the camshafts.
(e) Remove the camshaft timing tube from the intake cam-
shaft.