Nissan Terrano model r20 series 2004. Instruction — part 38
5. Remove valve oil seals using valve oil seal puller (SST).
6. Remove valve spring seats.
7. Before removing valve spring seats, perform valve seat contact
check. (Refer to EM-60.)
8. Before removing valve guides, perform valve guide clearance
check. (Refer to below.)
Inspection
CYLINDER HEAD DISTORTION
Using straightedge and feeler gauge, check the bottom of the cyl-
inder head for distortion.
Limit: 0.2 mm (0.008 in)
VALVE DIMENSION
Using micrometer, measure the dimensions of each part.
Standard
Unit: mm (in)
Intake valve
Exhaust valve
L
113.5 (4.4685)
113.5 (4.4685)
T
1.5 (0.059)
1.5 (0.059)
φ
d
6.962 - 6.977
(0.2741 - 0.2747)
6.945 - 6.960
(0.2734 - 0.2740)
φ
D
31.9 - 32.1
(1.256 - 1.264)
29.9 - 30.1
(1.177 - 1.185)
α
(degree)
45°00
′
- 45°30
′
45°00
′
- 45°30
′
VALVE GUIDE CLEARANCE
I
Perform the inspection before removing valve guides.
I
Check that the valve stem diameter is within specifications.
I
Push valve approximately 25 mm (0.98 in) toward combustion
chamber, move valve toward dial indicator to measure valve
movement.
I
Valve guide clearance is 1/2 of movement on dial indicator.
FEM065
FEM066
FEM067
FEM068
CYLINDER HEAD
ZD
Disassembly (Cont’d)
EM-58
Unit: mm (in)
Standard
Limit
Intake
0.023 - 0.056
(0.0009 - 0.0022)
0.18 (0.0071)
Exhaust
0.040 - 0.073
(0.0016 - 0.0029)
0.10 (0.0039)
I
If the measured value exceeds the limit, replace valve guide.
VALVE GUIDE REPLACEMENT
I
There is no setup for oversized valve guide.
1. Heat cylinder head to 110 to 130°C (230 to 266°F) in oil bath.
2. Using valve guide drift (multi-purpose tool: for 7.0 mm dia.), tap
valve guides out from the combustion chamber side.
3. Heat cylinder head to 110 to 130°C (230 to 266°F) in oil bath.
4. Using valve guide drift (multi-purpose tool: for 7.0 mm dia.),
press fit valve guides from camshaft side, referring to the
dimension shown in the figure.
5. Using valve guide reamer (multi-purpose tool), perform ream-
ing to the press-fitted valve guides.
Reaming specifications:
Intake/Exhaust
7.000 - 7.018 mm (0.2756 - 0.2763 in)
FEM069
FEM070
FEM071
FEM072
CYLINDER HEAD
ZD
Inspection (Cont’d)
EM-59
VALVE SEAT CONTACT
Check valve for any evidence of pitting at valve contact surface,
and reseat or replace if worn out excessively.
I
When repairing valve seats, check valve and valve guide
for wear beforehand. If worn, replace them. Then correct
valve seat.
I
The cutting should be done with both hands for uniform
cutting.
VALVE SEAT REPLACEMENT
I
When removing valve seat, replace it with oversized [0.5 mm
(0.0020 in)] valve seat.
1. Cut valve seat to make it thin, and pull it out.
2. Machine cylinder head inner diameter at valve seat installation
position.
Machining dimension:
Intake
33.500 - 33.515 mm (1.3189 - 1.3195 in) dia.
Exhaust
31.995 - 32.010 mm (1.2596 - 1.2602 in) dia.
3. Heat cylinder head to approximately 110 to 130°C (230 to
266°F) in oil bath.
4. After cooling valve seats sufficiently with dry ice, press fit it to
cylinder head.
CAUTION:
Do not touch the cooled valve seats directly by hand.
5. Using valve seat cutter (multi-purpose tool), finish processing
referring to the dimensions shown in the figure.
CAUTION:
When using valve seat cutter, grasp cutter handle with both
hands, press cutter onto contacting face all around, and cut
thoroughly. If cutter is pressed unevenly or repeatedly, the
valve seat surface may be damaged.
6. Using compound, perform valve fitting.
7. Check again to make sure that contacting status is satisfactory.
FEM073
FEM074
FEM075
CYLINDER HEAD
ZD
Inspection (Cont’d)
EM-60
For details of values (
q
1
to
q
10
), refer to EM-87, “Valve Seat” in
“SERVICE DATA AND SPECIFICATIONS (SDS)”.
VALVE SPRING RIGHT ANGLE
Position a straightedge to valve spring, turn the spring, and mea-
sure the maximum clearance value between top surface of spring
and the straightedge
Limit: 2.4 mm (0.094 in)
VALVE SPRING FREE LENGTH AND COMPRESSIVE
LOAD
Using valve spring tester, check the following.
Free length: 55.43 mm (2.1823 in)
Installation height: 40.8 mm (1.6063 in)
Installation load: 180 - 206 N (18.4 - 21.0 kg, 40.6 -
46.3 lb)
Height at valve open: 32.3 mm (1.2717 in)
Load at valve open: 336 - 372 N (34.3 - 37.9 kg, 75.6 -
83.6 lb)
Assembly
1. Install valve guides, referring to EM-60, “VALVE SEAT
REPLACEMENT”.
2. Install valve seats, referring to EM-60, “VALVE SEAT CON-
TACT”.
3. Using valve oil seal drift (SST), install valve oil seals referring
to the dimension shown in the figure.
I
The figure shows the dimension before valve spring seats are
installed.
4. Install valve spring seats.
5. Install valves.
I
Install the valves with bigger openings to intake valve side.
I
Note that valve layout here is different from that of conventional
the engine.
YEM035
FEM077
FEM078
FEM079
CYLINDER HEAD
ZD
Inspection (Cont’d)
EM-61
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