Lexus NX: Inspection

INSPECTION

PROCEDURE

1. INSPECT CYLINDER HEAD SUB-ASSEMBLY

(a) Using a precision straightedge and feeler gauge, measure the warpage of the contact surfaces where the cylinder head contacts the cylinder block and manifold.

Maximum Warpage:

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

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

If cracked, replace the cylinder head sub-assembly.

2. INSPECT INNER COMPRESSION SPRING

(a) Using a vernier caliper, measure the free length of the inner compression spring. Standard free length: 47.2 mm (1.86 in.)

(b) Using a steel square, measure the deviation of the inner compression spring. Maximum deviation: 1.05 mm (0.0413 in.) Maximum angle: 2° If the deviation is more than the maximum, replace the inner compression spring.

*a Deviation *b 30 mm (1.18 in.)

3. INSPECT INTAKE VALVE

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

Standard valve stem diameter:

5.470 to 5.485 mm (0.2154 to 0.2159 in.)

(b) Using a vernier caliper, measure the valve head margin thickness. Standard margin thickness: 1.0 mm (0.0394 in.) Minimum margin thickness: 0.50 mm (0.0197 in.) If the margin thickness is less than the minimum, replace the intake valve.

*a Margin Thickness

(c) Using a vernier caliper, measure the overall length of the valve.

Standard overall length:

103.92 mm (4.09 in.)

Minimum overall length:

103.42 mm (4.07 in.)

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

4. INSPECT EXHAUST VALVE

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

Standard valve stem diameter:

5.465 to 5.480 mm (0.2152 to 0.2157 in.)

(b) Using a vernier caliper, measure the valve head margin thickness. Standard margin thickness: 1.0 mm (0.0394 in.) Minimum margin thickness: 0.50 mm (0.0197 in.) If the margin thickness is less than the minimum, replace the exhaust valve.

*a Margin Thickness

(c) Using a vernier caliper, measure the overall length of the valve.

Standard overall length:

112.91 mm (4.45 in.)

Minimum overall length:

112.41 mm (4.43 in.)

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

5. INSPECT VALVE GUIDE BUSH OIL CLEARANCE

(a) Using a caliper gauge, measure the inside diameter of the valve guide bush. Standard bush inside diameter: 5.510 to 5.530 mm (0.2169 to 0.2177 in.)

(b) Subtract the valve stem diameter measurement from the guide bush inside diameter measurement.

Standard Oil Clearance:

Maximum Oil Clearance:

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

6. INSPECT INTAKE VALVE SEAT

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

(b) Lightly press the valve face against the intake valve seat. HINT: Do not rotate the valve while pressing the valve.

*a Width

(c) Check the valve face and intake valve seat.

(1) Check that the contact surfaces of the intake 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.).

If not, correct the intake valve seat.

(2) Check that the contact surfaces of the intake valve seat and valve face are even around the entire intake valve seat.

If not, correct the intake valve seat.

7. INSPECT EXHAUST VALVE SEAT

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

(b) Lightly press the valve face against the exhaust valve seat. HINT: Do not rotate the valve while pressing the valve.

*a Width

(c) Check the valve face and exhaust valve seat.

(1) Check that the contact surfaces of the exhaust valve seat and valve face are in the middle area of their respective surfaces, with the width between 1.2 and 1.6 mm (0.0472 and 0.0630 in.).

If not, correct the exhaust valve seat.

(2) Check that the contact surfaces of the exhaust valve seat and valve face are even around the entire exhaust valve seat.

If not, correct the exhaust valve seat.

8. INSPECT CAMSHAFT THRUST CLEARANCE

(a) Inspect the camshaft and No. 2 camshaft.

(1) Install the camshaft and No. 2 camshaft.

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(2) Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth. Standard thrust clearance: 0.060 to 0.155 mm (0.00236 to 0.00610 in.) Maximum thrust clearance: 0.170 mm (0.00669 in.) If the thrust clearance is more than the maximum, replace the camshaft housing sub-assembly. If the thrust surface is damaged, replace the camshaft.

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