Inspection

CYLINDER HEAD

Inspection After Disassembly


CYLINDER HEAD DISTORTION

Clean the surface of the cylinder head. Use a reliable straightedge and feeler gauge to check the flatness of cylinder head surface.
Revision: March 20122013 Infiniti JX





Check along six positions as shown.





If it exceeds the limit, replace the cylinder head.
The limit for cylinder head resurfacing is determined by the cylinder block resurfacing.





After resurfacing cylinder head, check that camshaft rotates freely by hand. If resistance is felt, cylinder head must be replaced.





VALVE GUIDE CLEARANCE






1.Measure valve deflection as shown. (Valve and valve guide mostly wear in this direction.)










2.If it exceeds the limit, check valve to valve guide clearance.
a.Measure valve stem diameter and valve guide inner diameter.
Refer to "Cylinder Head" [1][2]Cylinder Head Assembly.
b.Check that clearance is within specification.





c.If it exceeds the limit, replace valve or valve guide.

VALVE GUIDE REPLACEMENT

When valve guide is removed, replace with oversized [0.2 mm (0.008 in)] valve guide.
Revision: March 20122013 Infiniti JX





1.To remove valve guide, heat cylinder head to 110 - 130�C (230 266�
F) by soaking in heated oil.

WARNING:
Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.





2.Drive out the valve guide with a press [under a 20 kN (2.2 US
ton) pressure] or hammer and suitable tool.





3.Ream cylinder head valve guide hole.










4.Heat cylinder head to 110 - 130�C (230 - 266�F) by soaking in heated oil and press new valve guide from camshaft side into the cylinder head to the dimensions as shown.





WARNING:
Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
Revision: March 20122013 Infiniti JX





5.Using a valve guide reamer, apply a reamer finish to the valve guide.





VALVE SEAT CONTACT






- After confirming that the dimensions of valve guides and valves are within specifications, perform this procedure.
- Apply Prussian blue onto contacting surface of valve seat to check the condition of the valve contact on the surface.
- Check if the contact area band is continuous all around the circumference.
- If not, grind to adjust valve fitting and check again. If the contacting surface still has NG conditions even after the re-check, replace valve seat.

VALVE SEAT REPLACEMENT






1.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.





Be sure to ream in circles concentric to the valve guide center.
This will enable valve seat to fit correctly.
3.Heat cylinder head to 110 - 130�C (230 - 266�F) 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. Refer to "Cylinder Head" [1][2]Cylinder Head Assembly.
6.After cutting, lap valve seat with abrasive compound.
7.Check valve seating condition.















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 to adjust it. If it is longer, replace the valve seat with a new one.





VALVE SPRING SQUARENESS






Set try square along the side of valve spring and rotate the spring.
Measure the maximum clearance between the top face of spring and try square.





VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD






Check valve spring pressure at specified spring height.





If it is not within specifications, replace the spring.
Revision: March 20122013 Infiniti JX