Infiniti FX35, FX50 (S51). Manual - part 988

EM-252

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CYLINDER HEAD

2.

At each of several locations on bottom surface of cylinder head,
measure the distortion in six directions (A, B, C, D, E, F).

• If it exceeds the limit, replace VVEL ladder assembly & cylinder

head assembly.
NOTE:
Cylinder head assembly cannot be replaced as a single part,
because it is machined together with VVEL ladder assembly.

Valve Dimensions

• Check the dimensions of each valve. For the dimensions, refer to 

EM-285, "Cylinder Head"

.

• If dimensions are out of the standard. 
- Replace valve (EXH) and check valve seat contact. Refer to "VALVE SEAT CONTACT". (Exhaust side)
- Replace VVEL ladder assembly & cylinder head assembly. Refer to 

EM-227, "Exploded View"

. (Intake side)

NOTE:
Since the valve (INT) cannot be replaced by the piece, VVEL ladder assembly & cylinder head assembly
replacement are required.

Valve Guide Clearance

Valve Stem Diameter

• Measure the diameter of valve stem with micrometer (A).

Valve Guide Inner Diameter

• Measure the inner diameter of valve guide with bore gauge.

Valve Guide Clearance

• (Valve guide clearance) = (Valve guide inner diameter) – (Valve

stem diameter)

• If the calculated value exceeds the limit.
- Replace valve (EXH) and/or valve guide (EXH). Refer to 

EM-245, "Exploded View"

. (Exhaust side)

- Replace VVEL ladder assembly & cylinder head assembly. Refer to 

EM-227, "Exploded View"

. (Intake side)

NOTE:
Since the valve (INT) and valve guide (INT) cannot be replaced by the piece, VVEL ladder assembly & cylin-
der head assembly replacement are required.

Valve Seat Contact

• After confirming that the dimensions of valve guides and valves are within the specifications, perform this

procedure.

• Apply prussian blue (or white lead) 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 circum-

ference.

- 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 (EXH). Refer to 

EM-245, "Exploded View"

. (Exhaust

side)

- If not, replace VVEL ladder assembly & cylinder head assembly.

Refer to 

EM-227, "Exploded View"

. (Intake side)

Limit

: Refer to 

EM-285, "Cylinder Head"

.

JPBIA0176ZZ

Standard : 

Refer 

to 

EM-285, "Cylinder Head"

.

Standard

: Refer to 

EM-285, "Cylinder Head"

.

Standard

: Refer to 

EM-285, "Cylinder Head"

.

JPBIA0183ZZ

A

:  OK

B

:  NG

JPBIA0187ZZ

CYLINDER HEAD

EM-253

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C

D

E

F

G

H

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M

A

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N

P

O

NOTE:
Since the valve seat (INT) cannot be replaced by the piece, VVEL ladder assembly & cylinder head assem-
bly replacement are required.

Valve Spring (with valve spring seat) Squareness

• Set a try square (A) along the side of valve spring (with valve

spring seat) and rotate spring. Measure the maximum clearance
between the top of spring and try square.

• If it exceeds the limit.
- Replace valve spring (with valve spring seat) (EXH). Refer to 

EM-

245, "Exploded View"

. (Exhaust side)

- Replace VVEL ladder assembly & cylinder head assembly. Refer

to 

EM-227, "Exploded View"

. (Intake side)

NOTE:
Since the valve spring (with valve spring seat) (INT) cannot be replaced by the piece, VVEL ladder assembly
& cylinder head assembly replacement are required.

Valve Spring Dimensions and Valve Spring Pressure Load

• Check the valve spring (with valve spring seat) pressure at speci-

fied spring height.

• If the installation load or load with valve open is out of the stan-

dard.

- Replace valve spring (with valve spring seat) (EXH). Refer to 

EM-

245, "Exploded View"

. (Exhaust side)

- Replace VVEL ladder assembly & cylinder head assembly. Refer

to 

EM-227, "Exploded View"

. (Intake side)

NOTE:
Since the valve spring (with valve spring seat) (INT) cannot be replaced by the piece, VVEL ladder assembly
& cylinder head assembly replacement are required.

INSPECTION AFTER ASSEMBLY

Inspection for Leakage

The following are procedures for checking fluid leakage, lubricant leakage.

• Before starting engine, check oil/fluid levels including engine coolant and engine oil. If any are less than the

required quantity, fill them to the specified level. Refer to 

MA-12, "Fluids and Lubricants"

.

• Follow the procedure below to check for fuel leakage.
- Turn ignition switch to the “ON” position (with engine stopped). With fuel pressure applied to fuel piping,

check for fuel leakage at connection points.

- Start engine. With engine speed increased, check again for fuel leakage at connection points.
• Run engine to check for unusual noise and vibration.

NOTE:
If hydraulic pressure inside chain tensioner drops after removal/installation, slack in guide may generate a
pounding noise during and just after the engine start. However, this does not indicate a malfunction. The
noise will stop after hydraulic pressure rises.

• Warm up engine thoroughly to check that there is no leakage of fuel, or any oil/fluids including engine oil and

engine coolant.

• Bleed air from lines and hoses of applicable lines, such as in cooling system.
• After cooling down engine, again check oil/fluid levels including engine oil and engine coolant. Refill them to

the specified level, if necessary.

B

:  Contact

Limit

: Refer to 

EM-285, "Cylinder Head"

.

JPBIA0189ZZ

Standard

: Refer to 

EM-285, "Cylinder Head"

.

SEM113

EM-254

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CYLINDER HEAD

Summary of the inspection items:

* Transmission/transaxle/CVT fluid, power steering fluid, brake fluid, etc.

Items

Before starting engine

Engine running

After engine stopped

Engine coolant

Level

Leakage

Level

Engine oil

Level

Leakage

Level

Other oils and fluids*

Level

Leakage

Level

Fuel

Leakage

Leakage

Leakage

CYLINDER BLOCK

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CYLINDER BLOCK

Exploded View

INFOID:0000000005245259

1.

Knock sensor

2.

Cylinder block

3.

Side bolt

4.

Thrust bearing

5.

Main bearing (upper)

6.

Crankshaft key

7.

Crankshaft

8.

Main bearing (lower)

9.

Main bearing cap

JPBIA2289GB