Nissan Pathfinder. Manual — part 564
CYLINDER HEAD
EM-95
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Check along six positions as shown.
If it exceeds the limit, replace the cylinder head.
The limit for cylinder head resurfacing is determined by the cyl-
inder block resurfacing.
After resurfacing cylinder head, check that camshaft rotates freely by hand. If resistance is felt, cylinder head
must be replaced.
VALVE GUIDE CLEARANCE
1. Measure valve deflection as shown. (Valve and valve guide
mostly wear in this direction.)
2. If it exceeds the limit, check valve to valve guide clearance.
a. Measure valve stem diameter and valve guide inner diameter.
b. Check that clearance is within specification.
(Valve guide clearance) = (Valve guide inner diameter) - (Valve
stem diameter)
c. If it exceeds the limit, replace valve or valve guide.
VALVE GUIDE REPLACEMENT
When valve guide is removed, replace with oversized [0.2 mm (0.008 in)] valve guide.
Head surface distortion
Limit
: 0.1 mm (0.004 in)
Standard
: Less than 0.03 mm
(0.0012 in)
Resurfacing Limit
Amount of cylinder head resurfacing is (A).
Amount of cylinder block resurfacing is (B).
The maximum limit
: A + B = 0.2 mm (0.008 in)
Nominal cylinder head height
: 126.3 - 126.5 mm (4.972 - 4.980 in)
SEM861E
Valve deflection limit (dial gauge reading)
Intake
: 0.24 mm (0.0094 in)
Exhaust
: 0.28 mm (0.0110 in)
SEM178F
Valve to valve guide clearance standard
Intake
: 0.020 - 0.053 mm (0.0008 - 0.0021 in)
Exhaust
: 0.040 - 0.073 mm (0.0016 - 0.0029 in)
Valve to valve guide clearance limit
Intake
: 0.08 mm (0.0031 in)
Exhaust
: 0.1 mm (0.004 in)
SEM938C
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< REMOVAL AND INSTALLATION >
CYLINDER HEAD
1. To remove valve guide, heat cylinder head to 110 - 130
°C (230 -
266
°F) by soaking in heated oil.
WARNING:
Cylinder head contains heat. When working, wear protective
equipment to avoid getting burned.
2. Drive out the valve guide with a press [under a 20 kN (2.2 US
ton) pressure] or hammer and suitable tool.
3. Ream cylinder head valve guide hole.
4. Heat cylinder head to 110 - 130
°C (230 - 266°F) by soaking in
heated oil and press new valve guide from camshaft side into
the cylinder head to the dimensions as shown.
WARNING:
Cylinder head contains heat. When working, wear protective
equipment to avoid getting burned.
SEM008A
SEM931C
Valve guide hole diameter
(for service parts), intake
and exhaust
: 10.175 - 10.196 mm
(0.4006 - 0.4014 in)
SEM932C
Projection (L)
: 12.6 - 12.8 mm (0.496 - 0.504 in)
SEM950E
CYLINDER HEAD
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5. Using a valve guide reamer, apply a reamer finish to the valve
guide.
VALVE SEAT CONTACT
• After confirming that the dimensions of valve guides and valves are
within specifications, perform this procedure.
• Apply prussian blue onto contacting surface of valve seat to check
the condition of the valve contact on the surface.
• Check if the contact area band is continuous all around the circum-
ference.
• If not, grind to adjust valve fitting and check again. If the contacting
surface still has NG conditions even after the re-check, replace
valve seat.
VALVE SEAT REPLACEMENT
1. Bore out old seat until it collapses. Boring should not continue
beyond the bottom face of the seat recess in cylinder head. Set
the machine depth stop to ensure this.
2. Ream cylinder head recess for service valve seat.
Be sure to ream in circles concentric to the valve guide cen-
ter.
This will enable valve seat to fit correctly.
3. Heat cylinder head to 110 - 130
°C (230 - 266°F) by soaking in
heated oil.
WARNING:
Cylinder head contains heat. When working, wear protec-
tive equipment to avoid getting burned.
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool to the specified dimensions. Refer to
.
6. After cutting, lap valve seat with abrasive compound.
7. Check valve seating condition.
Intake and exhaust
finished size
: 6.000 - 6.018 mm
(0.2362 - 0.2369 in)
SEM932C
SBIA0322E
Oversize
: 0.5 mm (0.020 in)
Intake
: 38.500 - 38.516 mm
(1.5157 - 1.5164 in)
Exhaust
: 32.100 - 32.116 mm
(1.2638 - 1.2644 in)
SEM795A
SEM008A
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< REMOVAL AND INSTALLATION >
CYLINDER HEAD
8. Use a depth gauge to measure the distance between the mount-
ing surface of the cylinder head spring seat and the valve stem
end. If the distance is shorter than specified, repeat step 5 to
adjust it. If it is longer, replace the valve seat with a new one.
VALVE SPRING SQUARENESS
Set try square along the side of valve spring and rotate the spring.
Measure the maximum clearance between the top face of spring and
try square.
VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD
Check valve spring pressure at specified spring height.
If it is not within specifications, replace the spring.
Seat face angle (
α)
: 45
° 15' - 45° 45' de-
grees/minutes
Contacting width (W) for intake
: 1.18 - 1.22 mm
(0.0465 - 0.0480 in)
Contacting width (W) for exhaust : 1.38 - 1.42 mm
(0.0543 - 0.0559 in)
SEM892B
Valve seat resurface limit (L)
intake
: 41.16 - 41.76 mm
(1.6205 - 1.6441 in)
Valve seat resurface limit (L)
exhaust
: 41.09 - 41.69 mm
(1.6177 - 1.6413 in)
SEM621F
Out-of-square limit
: Less than 2.0 mm (0.079 in)
PBIC0080E
Standard
: 166 - 188 N (16.9 - 19.2 kg, 37.3 - 42.3 lb) at
height 37.0 mm (1.457 in)
Limit
: 373 - 421 N (38.0 - 42.9 kg, 84 - 95 lb) at
height 27.2 mm (1.071 in)
SEM113
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