Infiniti QX56 (JA60). Manual - part 480

EM-74

< ON-VEHICLE REPAIR >

CYLINDER HEAD

VALVE GUIDE REPLACEMENT

When the valve guide is removed, replace it with an oversized (0.2 mm, 0.008 in) valve guide.
1. To remove the valve guide, heat the cylinder head to 110

° to

130

°C (230° to 266°F) by soaking it in heated oil.

2. Remove the valve guide using suitable tool.

CAUTION:

Cylinder head contains heat. When working, wear protec-

tive equipment to avoid getting burned.

3. Ream the cylinder head valve guide hole using suitable tool.

4. Heat the cylinder head to 110

° to 130°C (230° to 266°F) by

soaking it in heated oil.

SEM008A

SEM931C

Valve guide hole diameter: 
Standard

Intake and exhaust : 9.975 - 9.996 mm (0.3927 - 

0.3935 in)

Oversize (service)

Intake and exhaust : 10.175 - 10.196 mm (0.4006 

- 0.4014 in)

SEM932C

SEM008A

CYLINDER HEAD

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5. Press the valve guide from the camshaft side to the dimensions

as shown.

CAUTION:

Cylinder head contains heat. When working, wear protec-

tive equipment to avoid getting burned.

6. Ream the cylinder head valve guide using suitable tool.

VALVE SEAT CONTACT

• After confirming that the dimensions of the valve guides and valves

are within specifications, perform this procedure. 

• Apply prussian blue (or white lead) onto the contacting surface of

the valve seat to check the condition of the valve contact on the

surface.

• Check if the contact area band is continuous all around the circum-

ference.

• If not, grind to adjust the valve fit and check again. If the contacting

surface still has NG conditions even after the re-check, replace the

valve seat.

VALVE SEAT REPLACEMENT

When the valve seat is removed, replace it with oversized (0.5 mm, 0.020 in) valve seat.
1. Bore out the old seat until it collapses. Boring should not continue beyond the bottom face of the seat

recess in the cylinder head. Set the machine depth stop to ensure this.

2. Ream the cylinder head recess diameter for service valve seat.

• Be sure to ream in circles concentric to the valve guide center.

• This will enable valve seat to fit correctly.

KBIA2530E

Valve guide inside diameter:

Intake and exhaust : 6.000 - 6.018 mm (0.2362 

- 0.2369 in)

SEM932C

SBIA0322E

Oversize [0.5 mm (0.020 in)] (Service):

Intake

: 38.500 - 38.516 mm (1.5157 - 1.5164 in)

Exhaust

: 32.700 - 32.716 mm (1.2874 - 1.2880 in)

SEM795A

EM-76

< ON-VEHICLE REPAIR >

CYLINDER HEAD

3. Heat the cylinder head to 110

° to 130°C (230° to 266°F) by

soaking it in heated oil.

4. Cool the valve seats well with dry ice. Force fit the valve seat into the cylinder head.

CAUTION:

• Avoid directly touching cold valve seats.

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

5. Finish the seat to the specified dimensions using suitable tool.

Refer to 

EM-108, "Standard and Limit"

.

CAUTION:

When using valve seat cutter, firmly grip the cutter handle

with both hands. Then, press on the contacting surface all

around the circumference to cut in a single drive. Improper

pressure on the cutter or cutting many different times may

result in stage valve seat. 

6. Grind to obtain the dimensions indicated as shown.

• Using compound, grind to adjust valve fitting. 

7. Check again for normal contact.

VALVE SPRING SQUARENESS

SEM008A

SEM934C

KBIA2531E

KBIA2544E

CYLINDER HEAD

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• 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.

• If measurement is not within specifications, replace the valve

spring.

VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD

• Check the valve spring pressure at the specified spring height.

• If measurement is not within specifications, replace the valve spring.

Limit

: Less than 2.2 mm (0.087 in)

PBIC0080E

Standard:

Intake and exhaust

Free height:

50.58 mm (1.9913 in)

Installation height:

37.0 mm (1.457 in)

Installation pressure:

165.8 - 187.0 N (16.9 - 
19.1 kg, 37- 42 lb)

Height during valve open: 28.2 mm (1.110 in)
Load with valve open:

314.8 - 355.0 N (32.1 - 
36.2 kg, 71 - 80 lb)

SEM113