Nissan Terrano r20e. Manual — part 304
Inspection
CYLINDER HEAD DISTORTION
Cylinder head distortion:
Standard
Less than 0.07 mm (0.0028 in)
Limit
0.2 mm (0.008 in)
If beyond the specified limit, correct with a surface grinder.
Cylinder head minimum height:
89.7 mm (3.531 in)
VALVE GUIDE CLEARANCE
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Valve guide clearance should be measured parallel with
rocker arm. (Generally, a large amount of wear occurs in
this direction.)
Valve to guide clearance:
Limit
Intake 0.15 mm (0.0059 in)
Exhaust 0.20 mm (0.0079 in)
Maximum allowable deflection
(Dial indicator reading)
Intake 0.30 mm (0.0118 in)
Exhaust 0.40 mm (0.0157 in)
I
To determine the correct replacement part, measure valve
stem diameter and valve guide inner diameter.
Valve stem diameter:
Standard
Intake
7.965 - 7.980 mm (0.3135 - 0.3142 in)
Exhaust
7.945 - 7.960 mm (0.3128 - 0.3134 in)
Valve guide inner diameter:
8.000 - 8.015 mm (0.3150 - 0.3156 in)
VALVE GUIDE REPLACEMENT
1. Heat cylinder head 150 to 160°C (302 to 320°F) in oil.
2. Drive out valve guide with a hammer and suitable tool.
SEM648B
SEM586A
EM030
SEM649B
SEM628B
CYLINDER HEAD
TD27Ti
EM-107
3. Press service valve guide into cylinder head using suitable tool
until the guide projects out 16±0.2 mm (0.63±0.08 in).
4. Ream valve guide.
Finished size:
8.000 - 8.015 mm (0.3150 - 0.3156 in)
VALVE SEATS
Check valve for any evidence of pitting at valve contact surface,
and reseat or replace if worn out excessively.
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When repairing valve seats, check valve and valve guide
for wear beforehand. If worn, replace them. Then correct
valve seat.
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The cutting should be done with both hands for uniform
cutting.
REPLACING VALVE SEAT FOR SERVICE PARTS
1. Before out old seat until it collapses or remove valve seats with
Tool.
Place a copper seat between contact surface of Tool and cyl-
inder head.
2. Place new valve seats on dry ice and allow them to cool for five
minutes.
WARNING:
Do not touch cooled valve seats with bare hand.
3. Heat cylinder head to 80°C (176°F).
4. Install cooled valve seats on cylinder head with Tool.
NEM178
SEM630B
SEM024
SEM631B
SEM632B
CYLINDER HEAD
TD27Ti
Inspection (Cont’d)
EM-108
5. Stake exhaust valve seat at five places with punch.
When staking valve seat, select different places than those
staked before.
6. Cut or grind valve seat using suitable tool at the specified
dimensions. Refer to SDS.
7. After cutting, lap valve seat with a lapping compound.
8. Check contact condition of valve seat.
COMBUSTION CHAMBER
Check combustion chamber for cracks and other damage. If
necessary, replace.
REPLACING COMBUSTION CHAMBER
Usually combustion chamber should not be removed.
1. Remove combustion chamber so that cylinder head cannot be
damaged.
2. Install combustion chamber.
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Identification of combustion chambers
Identification mark
(on combustion chamber)
Outer diameter “D”
mm (in)
2
37 (1.46)
(1) Cool combustion chamber with dry ice for approximately 5 to 10
minutes.
WARNING:
Do not touch cooled combustion chamber with bare hands.
SEM087
NEM161
EEM116
CYLINDER HEAD
TD27Ti
Inspection (Cont’d)
EM-109
(2) Align combustion chamber knock pin with cylinder head notch,
and drive in combustion chamber with a soft hammer.
3. Check amount of protrusion of combustion chamber.
Protrusion:
Standard
Less than 0.10 mm (0.0039 in)
VALVE DIMENSIONS
Check dimensions in each valve. For dimensions, refer to SDS.
When valve head has been worn down to 0.5 mm (0.020 in) in
margin thickness, replace the valve.
Grinding allowance for valve stem tip is 0.2 mm (0.008 in) or
less.
VALVE SPRING SQUARENESS
Out-of-square “S”:
Less than 2.0 mm (0.079 in)
VALVE SPRING PRESSURE
Refer to SDS.
SEM634B
SEM188A
SEM635B
EM113
CYLINDER HEAD
TD27Ti
Inspection (Cont’d)
EM-110
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