CYLINDER HEAD INSPECTION

INSPECT CYLINDER HEAD SUB-ASSEMBLY

Using a straightedge and feeler gauge, measure the warpage of the contact surfaces as shown in the illustration.

*a	Lower Side	*b	Exhaust Side
*c	Intake Side	-	-

Maximum Warpage

0.05 mm (0.00197 in.)

Tip:

If the warpage is greater than the maximum, replace the cylinder head sub-assembly.

INSPECT CYLINDER HEAD SUB-ASSEMBLY FOR CRACKS

Using a dye penetrant, check the combustion chamber, intake ports, exhaust ports and cylinder head sub-assembly surface for cracks.

Tip:
If a crack is found, replace the cylinder head sub-assembly.

INSPECT VALVE SEATS

Apply a light coat of Prussian blue to the valve face.

*a	Width

Lightly press the valve face against the valve seat.

Note:

Do not rotate the valve while pressing the valve.

Check the valve face and valve seat.
1. Check that the contact surfaces of the valve seat and valve face are in the middle area of their respective surfaces, with the width between 1.0 and 1.4 mm (0.0394 and 0.0551 in.).
2. Check that the contact surfaces of the valve seat and valve face are even around the entire valve seat.
  
  Tip:
  If not, resurface the valve seat.

INSPECT CAMSHAFT THRUST CLEARANCE

Install the camshaft and No. 2 camshaft.
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Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.

Standard Thrust Clearance

0.100 to 0.225 mm (0.00394 to 0.00886 in.)

Maximum Thrust Clearance

0.240 mm (0.00944 in.)

Tip:
If the thrust clearance is greater than the maximum, replace the cylinder head sub-assembly. If damage is found on the camshaft thrust surfaces, replace the camshaft.

INSPECT CAMSHAFT OIL CLEARANCE

Clean the 7 bearing caps and camshaft journals.
Place the camshaft and No. 2 camshaft on the cylinder head sub-assembly.

*a	Plastigage

Lay a strip of Plastigage across the camshaft journal in the axial direction.

Install the camshaft bearing caps.
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Remove the camshaft bearing caps.
Click here

*a	Plastigage

Measure the Plastigage at its widest point.

Standard Oil Clearance


Item	Specified Condition (Intake Side)	Specified Condition (Exhaust Side)
Camshaft No. 1 journal	0.025 to 0.061 mm (0.000984 to 0.00240 in.)	0.037 to 0.073 mm (0.00146 to 0.00287 in.)
Camshaft other journal	0.035 to 0.072 mm (0.00138 to 0.00283 in.)	0.035 to 0.072 mm (0.00138 to 0.00283 in.)

Maximum Oil Clearance


Item	Specified Condition (Intake Side)	Specified Condition (Exhaust Side)
Camshaft No. 1 journal	0.09 mm (0.00354 in.)	0.10 mm (0.00393 in.)
Camshaft other journal	0.10 mm (0.00393 in.)	0.10 mm (0.00393 in.)

Note:

Completely remove the Plastigage after the inspection.

Tip:

If the oil clearance is greater than the maximum, replace the camshaft.
If necessary, replace the cylinder head sub-assembly.

INSPECT INNER COMPRESSION SPRING

*a	Steel Square

Using a steel square, measure the angle of the inner compression spring.

Maximum Deviation

1.5 mm (0.0591 in.)

Maximum Angle

2°

Tip:

If the angle is greater than the maximum, replace the inner compression spring.

Using a vernier caliper, measure the free length of the inner compression spring.

Standard Free Length

56.75 mm (2.2342 in.)

Tip:
If the free length is not as specified, replace the inner compression spring.

INSPECT INTAKE VALVE

*a	Overall Length

Using a vernier caliper, measure the overall length of the intake valve.

Standard Overall Length

88.39 mm (3.4799 in.)

Minimum Overall Length

87.89 mm (3.4602 in.)

Tip:

If the overall length is less than the minimum, replace the intake valve.

Using a micrometer, measure the diameter of the intake valve stem.

Standard Valve Stem Diameter

4.970 to 4.985 mm (0.1957 to 0.1963 in.)

Tip:
If the intake valve stem diameter is not as specified, check the intake valve guide bush oil clearance.

*a	Margin Thickness

Using a vernier caliper, measure the intake valve head margin thickness.

Standard Margin Thickness

1.0 mm (0.0394 in.)

Minimum Margin Thickness

0.5 mm (0.0197 in.)

Tip:

If the margin thickness is less than the minimum, replace the intake valve.

INSPECT EXHAUST VALVE

*a	Overall Length

Using a vernier caliper, measure the overall length of the exhaust valve.

Standard Overall Length

89.11 mm (3.5083 in.)

Minimum Overall Length

88.61 mm (3.4886 in.)

Tip:

If the overall length is less than the minimum, replace the exhaust valve.

Using a micrometer, measure the diameter of the exhaust valve stem.

Standard Valve Stem Diameter

4.965 to 4.980 mm (0.1955 to 0.1961 in.)

Tip:
If the exhaust valve stem diameter is not as specified, check the exhaust valve guide bush oil clearance.

*a	Margin Thickness

Using a vernier caliper, measure the exhaust valve head margin thickness.

Standard Margin Thickness

1.0 mm (0.0394 in.)

Minimum Margin Thickness

0.5 mm (0.0197 in.)

Tip:

If the margin thickness is less than the minimum, replace the exhaust valve.

INSPECT VALVE GUIDE BUSH OIL CLEARANCE

Using a caliper gauge, measure the inside diameter of the valve guide bush.

Standard Valve Guide Bush Inside Diameter

5.010 to 5.030 mm (0.1972 to 0.1980 in.)

Subtract the valve stem diameter measurement from the valve guide bush inside diameter measurement.

Standard Oil Clearance


Item	Specified Condition
Intake	0.025 to 0.060 mm (0.000984 to 0.00236 in.)
Exhaust	0.030 to 0.065 mm (0.00118 to 0.00256 in.)

Maximum Oil Clearance


Item	Specified Condition
Intake	0.080 mm (0.00315 in.)
Exhaust	0.100 mm (0.00394 in.)

Tip:

If the oil clearance is greater than the maximum, replace the valve and valve guide bush.