Valve Clearance: Service and Repair

CAMSHAFT VALVE CLEARANCE

Valve Clearance


CHECKING


CAUTION:
Check valve clearance while engine is cold and not running.
NOTE:
Perform valve clearance inspection after removal, installation or replacement of camshaft or valve related parts, or as necessary.
1.Remove the air duct with air cleaner case, collectors, hoses, wires, harnesses, and connectors. Refer to
"Removal and Installation" Removal and Installation.
2.Remove the intake manifold collector. Refer to "Removal and Installation" Removal and Installation.
3.Remove the ignition coils and spark plugs. Refer to "Exploded View" Exploded View.
4.Remove the rocker covers. Refer to "Exploded View" Exploded View.





5.Set No.1 cylinder at TDC on its compression stroke.





a.Align pointer with TDC mark (A) on crankshaft pulley.





b.Check that the valve lifters on No.1 cylinder are loose and valve lifters on No.4 are tight. If not, turn the crankshaft one full revolution (360�
) and align as shown.
Revision: March 20122013 Infiniti JX





6.Check only the valves as shown.










a.Using a feeler gauge, measure the clearance between the valve lifter and camshaft.

"General Specification".
b.Record any valve clearance measurements which are out of specification. They will be used later to determine the required replacement lifter size.





7.Turn crankshaft 240�.
8.Set No.3 cylinder at TDC on its compression stroke.
Revision: March 20122013 Infiniti JX





9.Check only those valves as shown.





10.Turn the crankshaft 240� and align as above.
11.Set No.5 cylinder at TDC on its compression stroke.





12.Check only those valves as shown.





13.Perform adjustment if the measured values are out of the specification range.
14.Installation of components is in the reverse order of removal.

VALVE ADJUSTING


CAUTION:
Adjust valve clearance while engine is cold.
NOTE:
- Perform adjustment by selecting the correct head thickness of the valve lifter (adjusting shims are not used).
Revision: March 20122013 Infiniti JX
- The specified valve lifter thickness dimension is measured at room temperature.
- Use specifications for hot engine for hot engine condition to confirm valve clearances.
1.Remove the camshaft.
2.Remove the valve lifter that was measured as being outside the standard specifications.





3.Measure the center thickness of the removed lifter with a micrometer as shown.
4.Use the equation below to calculate the replacement valve lifter thickness.
Valve lifter thickness calculation:(C1 - C2) + t1=t


C1 = measured valve clearance
C2 = standard valve clearance t
1 = thickness of the removed lifter t = thickness of the replacement lifter





a.The thickness of the new valve lifter can be identified by the stamp mark (A) on the reverse side (inside the lifter).
NOTE:
Available thicknesses of the valve lifters (B) are: 7.88 - 8.40 mm (0.3102 - 0.3307 in), in 0.02 mm (0.0008 in) increments. Refer to
"Camshaft" [1][2]Camshaft, Engine
5.Install the selected replacement valve lifter.
6.Install the camshaft.
7.Rotate the crankshaft a few turns by hand.
8.Confirm that the valve clearances are within specification.
9.After the engine has been run to full operating temperature, confirm that the valve clearances are within specification.





Revision: March 20122013 Infiniti JX