INFINITI QX4 2001 Factory Service Manual

ComponentsNBEM0016
SEM441GA
1. Oil filler cap
2. Rocker cover
3. Camshaft bracket
4. Camshaft
5. PCV valve
6. Cylinder head
7. Blow-by hose8. Spark plug
9. Valve
10. Valve spring seat
11. Valve spring
12. Valve spring retainer
13. Valve collet14. Valve lifter
15. Shim
16. Chain tensioner
17. Spring
18. Tensioner sleeve
19. CVTC valve
CYLINDER HEAD
Components
EM-38

CAUTION:
IWhen installing camshafts, chain tensioners, oil seals, or
other sliding parts, lubricate contacting surfaces with new
engine oil.
IApply new engine oil to threads and seat surfaces when
installing cylinder head, camshaft sprocket, crankshaft
pulley, and camshaft bracket.
IAttach tags to valve lifters so as not to mix them up.
RemovalNBEM00171. Remove engine from vehicle. Refer to EM-57, ªRemoval and
Installationº.
2. Remove exhaust manifolds in reverse order of installation.
Refer to EM-13, ªExhaust Manifoldº.
3. Place engine on a work stand.
4. Remove aluminum oil pan. Refer to EM-15, ªRemovalº.
5. Remove timing chain. Refer to EM-23, ªRemovalº.
SEM964F
6. Remove intake manifold in reverse order of installation. Refer
to ªTIGHTENING PROCEDURESº, EM-12.
7. Remove water outlet.
SEM442G
8. Remove rear timing chain case bolts.
ILoosen in numerical order as shown in the figure.
SEM168FA
9. Remove rear timing chain case.
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CYLINDER HEAD
Components (Cont'd)
EM-39

SEM447G
10. Remove O-rings to cylinder head.
SEM534G
11. Remove O-rings to cylinder block.
SEM443G
12. Remove CVTC valves.
SEM856E
SEM857E
13. Remove intake and exhaust camshafts and camshaft brackets.
IEqually loosen camshaft bracket bolts in several steps in the
numerical order shown in the figure.
For reinstallation, be sure to put marks on camshaft
bracket before removal.
CYLINDER HEAD
Removal (Cont'd)
EM-40

SEM444G
14. Remove RH and LH camshaft chain tensioners from cylinder
head.
SEM859E
SEM860E
15. Remove cylinder head bolts.
ICylinder head bolts should be loosened in two or three
steps.
IA warped or cracked cylinder head could result from
removing in incorrect order.
SEM863E
16. Remove cylinder head.
DisassemblyNBEM0043Remove valve component parts.
Refer to EM-35, ªVALVE OIL SEALº.
ICheck the clearance before removing the valve guide. Refer to
EM-43, ªVALVE GUIDE CLEARANCEº.
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CYLINDER HEAD
Removal (Cont'd)
EM-41

SEM861E
InspectionNBEM0019CYLINDER HEAD DISTORTIONNBEM0019S01Clean surface of cylinder head.
Use a reliable straightedge and feeler gauge to check the flatness
of cylinder head surface.
Check along six positions shown in the figure.
Head surface flatness: Limit 0.1 mm (0.004 in)
If beyond the specified limit, resurface or replace it.
The limit for cylinder head resurfacing is determined by the
cylinder block resurfacing.
Resurfacing limit:
Amount of cylinder head resurfacing is ªAº.
Amount of cylinder block resurfacing is ªBº.
The maximum limit : A+ B = 0.2 mm (0.008 in)
After resurfacing cylinder head, check that camshaft rotates freely
by hand. If resistance is felt, cylinder head must be replaced.
Nominal cylinder head height:
126.3 - 126.5 mm (4.972 - 4.980 in)
SEM191F
CAMSHAFT VISUAL CHECKNBEM0019S02Check camshaft for scratches, seizure and wear.
CAMSHAFT RUNOUTNBEM0019S031. Measure camshaft runout at A and B as shown in the figure.
Runout (Total indicator reading):
Limit 0.05 mm (0.0020 in)
2. If it exceeds the limit, replace camshaft.
SEM549A
CAMSHAFT CAM HEIGHTNBEM0019S041. Measure camshaft cam height.
Standard cam height:
Intake and exhaust
44.465 - 44.655 mm (1.7506 - 1.7581 in)
Cam wear limit:
0.2 mm (0.008 in)
2. If wear is beyond the limit, replace camshaft.
SEM862E
CAMSHAFT JOURNAL CLEARANCENBEM0019S051. Install camshaft bracket and tighten bolts to the specified
torque.
2. Measure inner diameter ªAº of camshaft bearing.
Standard inner diameter:
No. 1: 26.000 - 26.021 mm (1.0236 - 1.0244 in)
No. 2, 3, 4: 23.500 - 23.521 mm (0.9252 - 0.9260 in)
CYLINDER HEAD
Inspection
EM-42

SEM012A
3. Measure outer diameter of camshaft journal.
Standard outer diameter:
No. 1: 25.935 - 25.955 mm (1.0211 - 1.0218 in)
No. 2, 3, 4: 23.445 - 23.465 mm (0.9230 - 0.9238 in)
4. If clearance exceeds the limit, replace camshaft and/or cylin-
der head.
Camshaft journal clearance:
Standard
No. 1: 0.045 - 0.086 mm (0.0018 - 0.0034 in)
No. 2, 3, 4: 0.035 - 0.076 mm (0.0014 - 0.0030 in)
Limit
0.15 mm (0.0059 in)
SEM864E
CAMSHAFT END PLAYNBEM0019S061. Install camshaft in cylinder head.
2. Measure camshaft end play.
Camshaft end play:
Standard
0.115 - 0.188 mm (0.0045 - 0.0074 in)
Limit
0.24 mm (0.0094 in)
SEM865E
CAMSHAFT SPROCKET RUNOUTNBEM0019S071. Install sprocket on camshaft.
2. Measure camshaft sprocket runout.
Runout (Total indicator reading):
Less than 0.15 mm (0.0059 in)
3. If it exceeds the limit, replace camshaft sprocket.
SEM178F
VALVE GUIDE CLEARANCENBEM0019S081. Measure valve deflection as shown in the figure. (Valve and
valve guide mostly wear in this direction.)
Valve deflection limit (Dial gauge reading):
Intake 0.24 mm (0.0094 in)
Exhaust 0.28 mm (0.0110 in)
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CYLINDER HEAD
Inspection (Cont'd)
EM-43

SEM938C
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 to valve guide clearance limit:
Intake 0.08 mm (0.0031 in)
Exhaust 0.1 mm (0.004 in)
c. If it exceeds the limit, replace valve or valve guide.
SEM008A
VALVE GUIDE REPLACEMENTNBEM0019S091. To remove valve guide, heat cylinder head to 110 to 130ÉC
(230 to 266ÉF) by soaking in heated oil.
SEM931C
2. Drive out valve guide with a press [under a 20 kN (2 ton, 2.2
US ton, 2.0 Imp ton) pressure] or hammer and suitable tool.
SEM932C
3. Ream cylinder head valve guide hole.
Valve guide hole diameter (for service parts):
10.175 - 10.196 mm (0.4006 - 0.4014 in)
SEM950E
4. Heat cylinder head to 110 to 130ÉC (230 to 266ÉF) and press
service valve guide onto cylinder head.
Projection ªLº:
12.6 - 12.8 mm (0.496 - 0.504 in)
5. Ream valve guide.
Finished size:
6.000 - 6.018 mm (0.2362 - 0.2369 in)
CYLINDER HEAD
Inspection (Cont'd)
EM-44

SEM934C
VALVE SEATSNBEM0019S10Check valve seats for any evidence of pitting at valve contact
surface, and reseat or replace if it has worn out excessively.
IBefore repairing valve seats, check valve and valve guide
for wear. If they have worn, replace them. Then correct
valve seat.
IUse both hands to cut uniformly.
SEM795A
REPLACING VALVE SEAT FOR SERVICE PARTSNBEM0019S111. 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.
Oversize [0.5 mm (0.020 in)]:
Intake 38.500 - 38.516 mm (1.5157 - 1.5164 in)
Exhaust 32.700 - 32.716 mm (1.2874 - 1.2880 in)
Be sure to ream in circles concentric to the valve guide
center.
This will enable valve seat to fit correctly.
SEM892B
3. Heat cylinder head to 110 to 130ÉC (230 to 266ÉF) by soaking
in heated oil.
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool to the specified
dimensions as shown in SDS (EM-79).
6. After cutting, lap valve seat with abrasive compound.
7. Check valve seating condition.
Seat face angle ªaº: 45É
Contacting width ªWº:
Intake 1.09 - 1.31 mm (0.0429 - 0.0516 in)
Exhaust 1.29 - 1.51 mm (0.0508 - 0.0594 in)
SEM621F
8. Use a depth gauge to measure the distance between the
mounting surface of the cylinder head spring seat and the
valve stem end. If the distance is shorter than specified, repeat
step 5 above to adjust it. If it is longer, replace the valve seat
with a new one.
Valve seat resurface limit ªLº:
Intake 41.07 - 41.67 mm (1.6169 - 1.6405 in)
Exhaust 41.00 - 41.60 mm (1.6142 - 1.6378 in)
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CYLINDER HEAD
Inspection (Cont'd)
EM-45

SEM188A
VALVE DIMENSIONSNBEM0019S12Check dimensions of each valve. For dimensions, refer to SDS
(EM-76).
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.
SEM288A
VALVE SPRINGNBEM0019S13SquarenessNBEM0019S13011. Measure dimension ªSº.
Out-of-square ªSº:
Less than 2.0 mm (0.079 in)
2. If it exceeds the limit, replace spring.
EM113
PressureNBEM0019S1302Check valve spring pressure at specified spring height.
Pressure:
Standard
202 N (20.6 kg, 45.4 lb) at height 37.0 mm (1.457 in)
Limit
More than 436 N (44.5 kg, 98.1 lb) at height 28.2
mm (1.110 in)
If it exceeds the limit, replace spring.
SEM960E
VALVE LIFTERNBEM0019S141. Check contact and sliding surfaces for wear or scratches.
SEM961E
2. Check diameter of valve lifter and valve lifter guide bore.
Valve lifter outer diameter:
34.960 - 34.975 mm (1.3764 - 1.3770 in)
CYLINDER HEAD
Inspection (Cont'd)
EM-46

SEM867E
Lifter guide bore diameter:
35.000 - 35.021 mm (1.3780 - 1.3788 in)
SEM085D
AssemblyNBEM00201. Install valve component parts.
IAlways use new valve oil seal. Refer to ªVALVE OIL
SEALº, EM-35.
IBefore installing valve oil seal, install valve spring seat.
IInstall valve spring (uneven pitch type) with its narrow
pitch side toward cylinder head side (paint mark).
IAfter installing valve component parts, tap valve stem tip with
plastic hammer to assure a proper fit.
SEM891E
InstallationNBEM00211. Before installing rear timing chain case, remove old liquid gas-
ket from mating surface using a scraper.
IAlso remove old liquid gasket from mating surface of cylinder
block.
SEM161F
IRemove old liquid gasket from the bolt hole and thread.
SEM892E
2. Before installing cam bracket, remove old liquid gasket from
mating surface using a scraper.
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CYLINDER HEAD
Inspection (Cont'd)
EM-47