1998 NISSAN PICK-UP Repair Manual

SEM814F
CYLINDER HEADKA
EM-24

CAUTION:
lWhen installing rocker arms, camshaft and oil seal, lubri-
cate contacting surfaces with new engine oil.
lWhen tightening cylinder head bolts and rocker shaft
bolts, lubricate bolt threads and seat surfaces with new
engine oil.
lHydraulic valve lifters are installed in each rocker arm.
If hydraulic valve lifter is kept on its side, even when
installed in rocker arm, there is a risk of air entering it.
When rocker arms are removed, stand them straight up
or soak them in new engine oil.
lDo not disassemble hydraulic valve lifter.
lAttach tags to valve lifters so as not to mix them up.
Removal
1. Release fuel pressure. Refer to EC section (``Fuel Pressure
Release'').
2. Drain coolant from radiator and drain plug of block.
3. Remove the following parts.
lPower steering drive belt
lPower steering pump, idler pulley and power steering brack-
ets
lVacuum hoses of swirl control valve and pressure control
solenoid valve
lAccelerator wire bracket
4. Remove bolts which hold intake manifold collector to intake
manifold.
5. Remove bolts which hold intake manifold to cylinder head
while raising collector upwards.
6. Remove exhaust manifold cover and exhaust manifold.
7. Remove rocker cover.
lWhen removing rocker cover, do not hit rocker cover
against rocker arm.
8. Set No. 1 piston at TDC on its compression stroke.
SEM878BA
SEM868BA
.NG
SEM216C
CYLINDER HEADKA
Rear Oil Seal
EM-25

lMake sure No. 1 cylinder is at TDC by looking at the distribu-
tor rotor position.
9. Loosen camshaft sprocket bolt.
lSupport timing chain by using Tool as shown in figure.
10. Apply paint marks to timing chain matched with mating marks
of camshaft sprockets.
11. Remove camshaft sprocket.
12. Remove front timing cover to cylinder head bolts.
SEM572F
SEM576F
SEM597F
SEM219C
SEM577F
CYLINDER HEADKA
Removal (Cont'd)
EM-26

13. Remove cylinder head.
lLoosen in numerical order.
lA warped or cracked cylinder head could result from
removing in incorrect order.
lLoosen cylinder head bolts in two or three steps.
Disassembly
1. Remove rocker shaft assembly.
a. When loosening bolts, evenly loosen from outside in
sequence.
b. Bolts should be loosened in two or three steps.
2. Remove camshaft.
lBefore removing camshaft, measure camshaft end play.
(Refer to ``Inspection''.)
3. Remove valve components with Tool.
4. Remove valve oil seals. (Refer to ``OIL SEAL REPLACE-
MENT'', EM-22.)
Inspection
CYLINDER HEAD DISTORTION
lClean surface of cylinder head.
lUse a reliable straightedge and feeler gauge to check the
flatness of cylinder head surface.
lCheck along six positions shown in figure.
Head surface flatness: mm (in)
Standard
Less than 0.03 (0.0012)
Limit
0.1 (0.004)
If beyond the specified limit, replace or resurface.
Resurfacing limit:
The limit for cylinder head resurfacing is determined by the
cylinder block resurfacing.
Amount of cylinder head resurfacing is ``A''
Amount of cylinder block resurfacing is ``B''
The maximum limit is as follows:
A+B=0.2mm(0.008 in)
After resurfacing cylinder head, check that camshaft rotates
freely by hand. If resistance is felt, cylinder head must be
replaced.
SEM588F
SEM598F
SEM211EA
AEM257.AEM257
CYLINDER HEADKA
Removal (Cont'd)
EM-27

Nominal cylinder head height:
98.8 - 99.0 mm (3.890 - 3.898 in)
CAMSHAFT VISUAL CHECK
Check camshaft for scratches, seizure and wear.
CAMSHAFT RUNOUT
1. Measure camshaft runout at the center journal.
Runout (Total indicator reading):
0 - 0.02 mm (0 - 0.0008 in)
2. If it exceeds the limit, replace camshaft.
CAMSHAFT CAM HEIGHT
1. Measure camshaft cam height.
Standard cam height:
44.43 - 44.58 mm (1.7492 - 1.7551 in)
Cam height wear limit:
0.2 mm (0.008 in)
2. If wear is beyond the limit, replace camshaft.
CAMSHAFT JOURNAL CLEARANCE
1. Install camshaft bracket and rocker shaft and tighten bolts to
the specified torque.
2. Measure inner diameter of camshaft bearing.
Standard inner diameter:
33.000 - 33.025 mm (1.2992 - 1.3002 in)
3. Measure outer diameter of camshaft journal.
Standard outer diameter:
32.935 - 32.955 mm (1.2967 - 1.2974 in)
4. If clearance exceeds the limit, replace camshaft and/or cyl-
inder head.
Camshaft journal clearance: mm (in)
Standard
0.045 - 0.090 (0.0018 - 0.0035)
Limit
0.12 (0.0047)
SEM231C.SEM231C
SEM549A
SEM229C
SEM230C
CYLINDER HEADKA
Inspection (Cont'd)
EM-28

CAMSHAFT END PLAY
1. Install camshaft in cylinder head.
2. Measure camshaft end play.
Camshaft end play: mm (in)
Standard
0.07 - 0.15 (0.0028 - 0.0059)
Limit
0.2 (0.008)
3. If end play exceeds the limit, replace camshaft and remea-
sure camshaft end play.
lIf end play still exceeds the limit after replacing camshaft,
replace cylinder head.
CAMSHAFT SPROCKET RUNOUT
1. Install sprocket on camshaft.
2. Measure camshaft sprocket runout.
Runout (Total indicator reading):
Limit 0.12 mm (0.0047 in)
3. If it exceeds the limit, replace camshaft sprocket.
VALVE GUIDE CLEARANCE
1. Measure valve deflection as shown in illustration. (Valve and
valve guide mostly wear in this direction.)
Valve deflection limit (Dial gauge reading):
0.15 mm (0.0059 in)
2. If it exceeds the limit, check valve to valve guide clearance.
a. Measure valve stem diameter and valve guide inner diam-
eter.
b. Check that clearance is within specification.
Valve to valve guide clearance = valve guide inner
diameter þ valve stem diameter: mm (in)
Standard
Intake
0.020 - 0.053 (0.0008 - 0.0021)
Exhaust
0.040 - 0.070 (0.0016 - 0.0028)
Limit 0.1 (0.004)
SEM228C
SEM232C.SEM232C
SEM451C
SEM449C
CYLINDER HEADKA
Inspection (Cont'd)
EM-29

c. If it exceeds the limit, replace valve and remeasure clear-
ance.
lIf clearance still exceeds the limit after replacing valve,
replace the valve guide.
VALVE GUIDE REPLACEMENT
1. To remove valve guide, heat cylinder head to 110 to 130ÉC
(230 to 266ÉF).
2. Drive out valve guide using a hammer and suitable tool or a
press [under a 20 kN (2 ton, 2.2 US ton, 2.0 Imp ton) pres-
sure].
3. Ream cylinder head valve guide hole.
Valve guide hole diameter
(for service parts): mm (in)
Intake
11.175 - 11.196 (0.4400 - 0.4408)
Exhaust
12.175 - 12.196 (0.4793 - 0.4802)
4. Heat cylinder head to 110 to 130ÉC (230 to 266ÉF) and press
service valve guide onto cylinder head.
Projection ``L'':
14.9 - 15.1 mm (0.587 - 0.594 in)
5. Ream valve guide.
Finished size: mm (in)
Intake
7.000 - 7.018 (0.2756 - 0.2763)
Exhaust
8.000 - 8.018 (0.3150 - 0.3157)
SEM008A
SEM223C
SEM212E
SEM225C
CYLINDER HEADKA
Inspection (Cont'd)
EM-30

VALVE SEATS
Check valve seats for pitting at contact surface. Resurface or
replace if excessively worn.
lBefore repairing valve seats, check valve and valve
guide for wear. If they have worn, replace them. Then
correct valve seat.
lUse both hands to cut uniformly.
REPLACING VALVE SEAT FOR SERVICE PARTS
1. Bore out old seat until it collapses. Set machine depth stop
so that boring cannot contact bottom face of seat recess in
cylinder head.
2. Ream cylinder head recess.
Reaming bore for service valve seat
Oversize [0.5 (0.020)]: mm (in)
Intake 36.500 - 36.516 (1.4370 - 1.4376)
Exhaust 42.500 - 42.516 (1.6732 - 1.6739)
Use the valve guide center for reaming to ensure valve seat
will have the correct fit.
3. Heat cylinder head to 110 to 130ÉC (230 to 266ÉF).
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool of the specified
dimensions. Refer to SDS, EM-92.
6. After cutting, lap valve seat with abrasive compound.
7. Check valve seating condition.
Seat face angle ``a'':
45 deg.
Contacting width ``W'': mm (in)
Intake
1.6 - 1.7 (0.063 - 0.067)
Exhaust
1.7 - 2.1 (0.067 - 0.083)
VALVE DIMENSIONS
Check dimensions of each valve. Refer to SDS, EM-93.
When valve head has been worn down to 0.5 mm (0.020 in) in
margin thickness, replace valve.
Grinding allowance for valve stem tip is 0.2 mm (0.008 in) or
less.
SEM227C
SEM795A
SEM008A
SEM892B
SEM188A
CYLINDER HEADKA
Inspection (Cont'd)
EM-31