Nissan Frontier. Manual — part 721
CYLINDER HEAD
EM-73
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Measure the diameter of valve stem with micrometer.
Valve Guide Inner Diameter
Measure the inner diameter of valve guide with inside micrometer.
Valve Guide Clearance
(Valve guide clearance) = (Valve guide inner diameter) – (Valve stem diameter).
• If it exceeds the limit, replace valve guide and/or valve.
VALVE GUIDE REPLACEMENT
When valve guide is removed, replace with oversized [0.2 mm (0.008 in)] valve guide.
1. To remove valve guide, heat cylinder head to 110
° to 130°C
(230
° to 266°F) by soaking in heated oil.
2. Drive out valve guide with a press [under a 20 kN (2 ton, 2.2 US
ton, 2.0 lmp ton) force] or suitable tool.
WARNING:
Cylinder head contains heat, when working, wear protective
equipment to avoid getting burned.
Standard
Intake
: 5.965 - 5.980 mm (0.2348 - 0.2354 in)
Exhaust
: 5.955 - 5.970 mm (0.2344 - 0.2350 in)
SEM938C
Standard
Intake and Exhaust
: 6.000 - 6.018 mm (0.2362 - 0.2369 in)
Valve guide clearance:
Standard
Intake
: 0.020 - 0.053 mm (0.0008 - 0.0021 in)
Exhaust : 0.030 - 0.063 mm (0.0012 - 0.0025 in)
Limit
Intake
: 0.08 mm (0.003 in)
Exhaust : 0.09 mm (0.004 in)
SEM008A
SEM931C
EM-74
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CYLINDER HEAD
3. Ream cylinder head valve guide hole using suitable tool.
4. Heat cylinder head to 110
° to 130°C (230° to 266°F) by soaking
in heated oil.
5. Press valve guide from camshaft side to the dimensions as
shown using suitable tool.
WARNING:
Cylinder head contains heat, when working, wear protective
equipment to avoid getting burned.
6. Apply reamer finish to valve guide using suitable tool.
VALVE SEAT CONTACT
Valve guide hole diameter (for service parts):
Intake and exhaust
: 10.175 - 10.196 mm (0.4006 - 0.4014 in)
SEM932C
SEM008A
Projection (H)
Intake
: 10.1 - 10.3 mm (0.398 - 0.406 in)
Exhaust
: 10.0 - 10.4 mm (0.394 - 0.409 in)
PBIC2187E
Standard
Intake and exhaust:
6.000 - 6.018 mm (0.2362 - 0.2369 in)
SEM932C
CYLINDER HEAD
EM-75
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• After confirming that the dimensions of valve guides and valves are
within specifications, perform this procedure.
• Apply prussian blue (or white lead) 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
When valve seat is removed, replace with oversized [0.5 mm (0.020 in)] valve seat.
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. Refer to
CAUTION:
Prevent scratching cylinder head by excessive boring.
2. Ream cylinder head recess diameter for service valve seat.
• Be sure to ream in circles concentric to the valve guide center.
This will enable valve seat to fit correctly.
3. Heat cylinder head to 110
° to 130°C (230° to 266°F) by soaking
in heated oil.
4. Provide valve seats cooled well with dry ice. Force fit valve seats into cylinder head.
WARNING:
• Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
CAUTION:
• Avoid directly touching cold valve seats.
5. Finish seat to the specified dimensions using suitable tool. Refer
.
CAUTION:
When using valve seat cutter, firmly grip cutter handle with
both hands. Then, press on the contacting surface all
around the circumference to cut in a single drive. Improper
pressure on the cutter or cutting many different times may
result in staged valve seat.
SBIA0322E
Oversize [0.5 mm (0.020 in)]
Intake
: 37.000 - 37.016 mm (1.4567 - 1.4573 in)
Exhaust
: 32.000 - 32.016 mm (1.2598 - 1.2605 in)
SEM795A
SEM008A
SEM934C
EM-76
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CYLINDER HEAD
6. Using compound, grind to adjust valve fitting.
7. Check again for normal contact.
VALVE SPRING SQUARENESS
• Set a try square along the side of valve spring and rotate spring.
Measure the maximum clearance between the top face of spring
and try square.
CAUTION:
Do not remove valve spring seat from valve spring.
• If it exceeds the limit, replace valve spring.
VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD
• Check valve spring pressure with valve spring seat installed at the
specified spring height. Refer to
CAUTION:
Do not remove valve spring seat from valve spring.
• If the installation load or load with valve open is out of the stan-
dard, replace valve spring.
Limit
Intake
: 1.8 mm (0.071 in)
Exhaust
: 1.9 mm (0.075 in)
PBIC0080E
SEM113
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