Inspection [11/2021 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus IS 500, 2023 Lexus IS 500, and 2022 Lexus IS 500. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT CYLINDER HEAD FOR FLATNESS

Using a precision straightedge and feeler gauge, check the surfaces which contact the cylinder block sub-assembly and manifolds for warpage.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Cylinder Head Bottom	*b	Intake Side
*c	Exhaust Side	-	-

Standard Warpage

Item	Specified Condition
Cylinder Head Bottom	0.05 mm (0.00197 in.)
Intake Side	0.08 mm (0.00315 in.)
Exhaust Side	0.05 mm (0.00197 in.)

Maximum Warpage

0.10 mm (0.00394 in.)

If the warpage is more than the maximum, replace the cylinder head.

INSPECT CYLINDER HEAD FOR CRACKS

Using a dye penetrant, check the intake ports, exhaust ports and cylinder head surface for cracks.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

If cracks are found, replace the cylinder head.

INSPECT INTAKE VALVE

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Valve Stem Diameter

5.470 to 5.485 mm (0.215 to 0.216 in.)

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

See step 8

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Margin Thickness

Standard Margin Thickness

1.25 mm (0.0492 in.)

Minimum Margin Thickness

0.50 mm (0.0197 in.)

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

Using a vernier caliper, measure the valve overall length.

Standard Overall Length

105.85 mm (4.17 in.)

Minimum Overall Length

105.35 mm (4.15 in.)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Overall Length

INSPECT EXHAUST VALVE

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard Valve Stem Diameter

5.465 to 5.480 mm (0.215 to 0.216 in.)

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

See step 8

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Margin Thickness

Standard Margin Thickness

1.4 mm (0.0551 in.)

Minimum Margin Thickness

0.50 mm (0.0197 in.)

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

Using a vernier caliper, measure the valve overall length.

Standard Overall Length

110.40 mm (4.35 in.)

Minimum Overall Length

109.90 mm (4.33 in.)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Overall Length

INSPECT INTAKE VALVE SEAT

Apply a light coat of Prussian blue to the intake valve face.
Lightly press the intake valve face against the intake valve seat.
NOTE:
Do not rotate the intake valve.

Check the intake valve face and intake valve seat by using the following procedure:

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Width

Check that the intake valve seat contacts the middle of the intake valve face with the width between 1.1 and 1.5 mm (0.0433 and 0.0591 in.).
If not, resurface the intake valve seat.
Check that the contact surfaces of the intake valve seat and intake valve face are even around the entire valve seat.
If not, resurface the intake valve seat.

INSPECT EXHAUST VALVE SEAT

Apply a light coat of Prussian blue to the exhaust valve face.
Lightly press the exhaust valve face against the exhaust valve seat.
NOTE:
Do not rotate the exhaust valve.

Check the exhaust valve face and exhaust valve seat by using the following procedure:

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Width

Check that the exhaust valve seat contacts the middle of the exhaust valve face with the width between 1.1 to 1.5 mm (0.0433 to 0.0591 in.).
If not, resurface the exhaust valve seat.
Check that the contact surfaces of the exhaust valve seat and exhaust valve face are even around the entire valve seat.
If not, resurface the exhaust valve seat.

INSPECT INNER COMPRESSION SPRING

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

Standard Free Length

Intake

52.17 mm (2.05 in.)

Exhaust

52.16 mm (2.05 in.)

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

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

Deviation

Maximum Deviation

1.8 mm (0.0709 in.)

Maximum Angle (Reference)

2°

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

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

5.510 to 5.530 mm (0.217 to 0.218 in.)

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

Standard Oil Clearance

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

Maximum Oil Clearance

Item	Specified Condition
Intake Side	0.08 mm (0.00315 in.)
Exhaust Side	0.10 mm (0.00394 in.)

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

INSPECT CAMSHAFT THRUST CLEARANCE

Install the camshaft.
Refer to INSTALLATION [11/2021 - ]

Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.

Standard Thrust Clearance

0.110 to 0.165 mm (0.00433 to 0.00650 in.)

Maximum Thrust Clearance

0.175 mm (0.00689 in.)

If the camshaft thrust clearance is greater than the maximum, replace the cylinder head.

If the camshaft thrust surface is damaged, replace the camshaft, No. 2 camshaft, No. 3 camshaft sub-assembly or No. 4 camshaft sub-assembly.