2010 INFINITI QX56 engine

EM-12
< FUNCTION DIAGNOSIS >
NOISE, VIBRATION, AND HARSHNESS (NVH) TROUBLESHOOTING
A: Closely related B: Related C: Sometimes related —: Not relatedFront of en-
gine
Squeak-
ing or
fizzing
AB—B—C
Drive belts
(Sticking or
slipping)Drive belts deflection
EM-13
Creaking A B A B A B Drive belts
(Slipping)Idler pulley bearing op-
eration
Squall
Creaking AB—BAB Water pump
noiseWater pump operation
CO-20
Rattle — — A — — — VTC VTC lock pin clearanceEM-62
Location of
noise Type of
noise Operating condition of engine
Source of noise Check item Refer-
ence page
Be-
fore
warm- up After
warm- up When
start- ing When
idling When
racing While
driv- ing
Revision: April 20092010 QX56

DRIVE BELTSEM-13
< ON-VEHICLE MAINTENANCE >
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EM
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ON-VEHICLE MAINTENANCE
DRIVE BELTS
Exploded ViewINFOID:0000000005148974
Checking Drive BeltsINFOID:0000000005148975
WARNING:
Be sure to perform when the engine is stopped.
1. Remove air duct and resonator assembly when inspecting drive belt.
2. Make sure that indicator (single line notch) of eac
h auto tensioner is within the allowable working range
(between three line notches).
NOTE:
• Check the drive belt auto tensioner indication when the engine is cold.
• The indicator notch is located on the moving side of the drive belt auto tensioner.
3. Visually check entire belt for wear, damage or cracks.
4. If the indicator is out of allowable working range or belt is damaged, replace the belt. Refer to EM-13
.
DRIVE BELT TENSION
There is no manual drive belt tension adjustment. The driv e belt tension is automatically adjusted by the drive
belt auto tensioner.
Removal and InstallationINFOID:0000000005148976
REMOVAL
1. Remove the air duct and resonator assembly. Refer to EM-25, "Removal and Installation".
1. Drive belt2. Power steering pump pulley 3. Generator pulley
4. Crankshaft pulley 5. A/C compressor6. Idler pulley
7. Cooling fan pulley 8. Water pump pulley9. Drive belt auto tensioner
A. Allowable working range
LBIA0391E
Revision: April 20092010 QX56

EM-18
< ON-VEHICLE MAINTENANCE >
CAMSHAFT VALVE CLEARANCE
CAMSHAFT VALVE CLEARANCE
Valve ClearanceINFOID:0000000005148982
INSPECTION
NOTE:
Perform the following inspection after removal, installation or replacement of camshaft or valve-related parts,
or if there are unusual engine conditions due to changes in valve clearance over time (starting, idling, and/or
noise).
1. Warm up the engine. Then stop the engine.
2. Remove the engine room cover. Refer to EM-24, "
Removal and Installation".
3. Remove the air cleaner and air duct assembly. Refer to EM-25, "
Removal and Installation".
4. Remove the RH bank and LH bank rocker covers using power tool. Refer to EM-38, "
Removal and Instal-
lation".
5. Turn the crankshaft pulley in the normal direction (clockwise when viewed from engine front) to align TDC identification notch
(without paint mark) with timing indicator.
6. At this time, make sure both the intake and exhaust cam noses of No. 1 cylinder (top front on LH bank) face outside.
• If they do not face outside, turn crankshaft pulley once more.
KBIA2476E
KBIA0400J
Revision: April 20092010 QX56

CAMSHAFT VALVE CLEARANCEEM-19
< ON-VEHICLE MAINTENANCE >
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7. Measure valve clearances at the locations marked “×
” as shown
in the table below (locations indicated with black arrow).
• : Engine front
• (black): Measurable at No.1 cylinder compression top dead center
• (white): Measurable at No. 3 cylinder compression top dead center
•A: RH
•B: LH
• C: Exhaust
• D: Intake
NOTE:
Firing order 1-8-7-3-6-5-4-2
• No. 1 cylinder compression TDC
• Measure valve clearance using suitable tool. Refer to EM-108,
"Standard and Limit".
CAUTION:
If the inspection was carried out with a cold engine, make
sure the values with a fully warmed up engine are still
within specifications.
8. Turn the crankshaft pulley clockwise 270 ° from the position of No. 1 cylinder compression TDC to obtain
No. 3 cylinder compression TDC.
Measuring position (RH bank) No. 2 cyl
(E) No. 4 cyl
(F) No. 6 cyl
(G) No. 8 cyl
(H)
No. 1 cylinder at TDC EXH
×
INT ××
Measuring position (LH bank) No. 1 cyl
(J) No. 3 cyl
(K) No. 5 cyl
(L) No. 7 cyl
(M)
No. 1 cylinder at TDC INT
××
EXH ××
WBIA0713E
KBIA0185E
Revision: April 20092010 QX56

EM-20
< ON-VEHICLE MAINTENANCE >
CAMSHAFT VALVE CLEARANCE
9. Measure valve clearances at the locations marked “×” as shown
in the table below (locations indicated with white arrow).
• : Engine front
• (black): Measurable at No.1 cylinder compression top dead center
• (white): Measurable at No. 3 cylinder compression top dead center
•A: RH
•B: LH
• C: Exhaust
•D: Intake
NOTE:
Firing order 1-8-7-3-6-5-4-2
• No. 3 cylinder compression TDC
• Measure valve clearance using suitable tool. Refer to EM-108,
"Standard and Limit".
CAUTION:
If the inspection was carried out with a cold engine, make
sure the values with a fully warmed up engine are still
within specifications.
Measuring position (RH bank) No. 2 cyl
(E) No. 4 cyl
(F) No. 6 cyl
(G) No. 8 cyl
(H)
No. 3 cylinder at TDC EXH
×
INT ×
Measuring position (LH bank) No. 1 cyl
(J) No. 3 cyl
(K) No. 5 cyl
(L) No. 7 cyl
(M)
No. 3 cylinder at TDC INT
××
EXH ××
WBIA0713E
KBIA0185E
Revision: April 20092010 QX56

CAMSHAFT VALVE CLEARANCEEM-21
< ON-VEHICLE MAINTENANCE >
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10. Turn the crankshaft pulley clockwise 90°
from the position of No.
3 cylinder compression TDC (clockwise by 360 ° from the posi-
tion of No. 1 cylinder compression TDC) to measure the intake
and exhaust valve clearances of No. 6 cylinder (G) and the
exhaust valve clearance of No. 2 cylinder (E).
• : Front
•A: RH
•B: LH
• C: Exhaust
• D: Intake
• E: No. 2 cylinder
• F: No. 4 cylinder
• G: No. 6 cylinder
• H: No. 8 cylinder
• J: No. 1 cylinder
• K: No. 3 cylinder
• L: No. 5 cylinder
• M: No. 7 cylinder
11. If out of specifications, adjust as necessary.
ADJUSTMENT
NOTE:
• Perform adjustment depending on the selected head thickness of the valve lifter.
• The specified valve lifter thickness is the dimension at normal temperatures. Ignore dimensional differences
caused by temperature. Us e the specifications for hot engine condition to adjust.
1. Remove the camshaft. Refer to EM-53, "
Removal and Installation".
2. Remove the valve lifters at the locations that are out of specification.
3. Measure the center thickness of the removed valve lifters using suitable tool.
4. Use the equation below to calculate the valve lifter thickness for replacement.
• Valve lifter thickness calculation:Thickness of replacement valve lifter = t1+ (C1 - C2)
t1 = Thickness of removed valve lifter
C1 = Measured valve clearance
C2= Standard valve clearance:
• Thickness of a new valve lifter can be identified by stamp marks on the reverse side (inside the cylinder).
Stamp mark N788 indicates 7.88 mm (0.3102 in) in thickness.
• Available thickness of valve lifter: 25 sizes with range 7.88 to 8.36 mm (0.3102 to 0.3291 in) in steps of 0.02 mm (0.0008 in)
(when manufactured at factory). Refer to EM-108, "
Standard
and Limit".
5. Install the selected valve lifter.
WBIA0713E
KBIA0057E
KBIA0119E
Revision: April 20092010 QX56

EM-22
< ON-VEHICLE MAINTENANCE >
CAMSHAFT VALVE CLEARANCE
6. Install the camshaft.
7. Manually turn the crankshaft pulley a few turns.
8. Make sure the valve clearances for a cold engine are within specifications. Refer to EM-108, "
Standard
and Limit".
9. After completing the repair, check the valve clearanc es again with the specifications for a warmed engine.
Make sure the values are wit hin specifications. Refer to EM-108, "
Standard and Limit".
Revision: April 20092010 QX56

COMPRESSION PRESSUREEM-23
< ON-VEHICLE MAINTENANCE >
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COMPRESSION PRESSURE
Checking Compression PressureINFOID:0000000005148983
1. Warm up the engine thoroughly. Then stop the engine.
2. Release the fuel pressure. Refer to EC-489, "
Fuel Pressure Check".
CAUTION:
If CONSULT-III is not used to release fuel pressure leave the fuel pump fuse disconnected until
step 7.
3. Remove the spark plug from each cylinder. Refer to EM-16, "
Removal and Installation".
4. Connect the engine tachometer (not required in use of CONSULT-III).
5. Install the compression tester with Tool into the spark plug hole.
6. With the accelerator pedal fully depressed, turn the ignition switch to “START” for cranking. When the gauge pointer stabi-
lizes, read the compression pressure and engine rpm. Perform
these steps to check each cylinder.
Unit: kPa (kg/cm2, psi) /rpm
CAUTION:
Always use a fully charged battery to obtain specified engine speed.
• If the engine speed is out of the specified range, check the battery liquid for proper gravity. Check the engine speed again with normal battery gravity.
• If the compression pressure is below the minimum value, check the valve clearances and parts associ-
ated with the combustion chamber (valve, valve seat , piston, piston ring, cylinder bore, cylinder head,
cylinder head gasket). After checking, measure the compression pressure again.
• If some cylinders have low compression pressure, pour a small amount of engine oil into the spark plug hole of the cylinder to re-check it for compression.
- If the added engine oil improves the compression, t he piston rings may be worn out or damaged. Check
the piston rings and replace if necessary.
- If the compression pressure remains at a low level despite the addition of engine oil, the valves may be malfunctioning. Check the valves for damage. Replace the valve or valve seat accordingly.
• If two adjacent cylinders have respectively low compression pressure and their compression remains low even after the addition of engine oil, the gaskets may be leaking, or a valve in adjacent cylinders
may be damaged. Inspect and repair as required.
7. Install the components in the reverse order of removal.
8. Start the engine and confirm that it runs smoothly.
9. Perform trouble diagnosis. If DTC appears, erase it. Refer to EC-74, "
Description".
Tool number : EG15050500 (J-45402)
Standard
MinimumDeference limit be-
tween cylinders
1,520 (15.5, 220) / 200 1,324 (13.5, 192) / 200 98 (1.0, 14) / 200WBIA0605E
Revision: April 20092010 QX56