CYLINDER HEAD INSPECTION

PROCEDURE

1. INSPECT CYLINDER HEAD SUB-ASSEMBLY

   
   

   1. Using a precision straightedge and feeler gauge, measure the warpage of the contact surfaces where the cylinder head contacts the cylinder block sub-assembly and manifold.

      

      *a	Cylinder Head Lower Side	*b	Intake Manifold Side
      *c	Exhaust Manifold Side	-	-

      Maximum Warpage
      Item Specified Condition Cylinder Head Lower Side 0.05 mm (0.00197 in.) Intake Manifold Side 0.10 mm (0.00394 in.) Exhaust Manifold Side 0.10 mm (0.00394 in.)

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

   2. 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 COMPRESSION SPRING

   
   
   1. 

      *a	Paint Mark

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

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

      Standard Free Length
      Paint Mark Specified Condition Intake Valve Side (Green) 52.67 mm (2.07 in.) Exhaust Valve Side (Purple) 61.22 mm (2.41 in.)

   2. 

      *a	35 mm (1.38 in.)
      *b	Deviation

      Using a steel square, measure the deviation of the compression spring at a compression spring that is 35 mm (1.378 in.) from the bottom of the compression spring (refer to the illustration).

      Maximum deviation
      1.22 mm (0.0480 in.)

      Maximum angle
      2°

      If the deviation is more than the maximum, replace the compression spring.

3. INSPECT INTAKE VALVE

   
   

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

      Standard intake valve stem diameter
      5.470 to 5.485 mm (0.215 to 0.216 in.)

   2. 

      *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
      0.50 mm (0.0197 in.)

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

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

   
   

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

      Standard exhaust valve stem diameter
      5.465 to 5.480 mm (0.215 to 0.216 in.)

   2. 

      *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
      0.50 mm (0.0197 in.)

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

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

   
   

   1. 

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

      Standard bush inside diameter
      5.510 to 5.530 mm (0.217 to 0.218 in.)

   2. Subtract the valve stem diameter measurement from the 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 more than the maximum, replace the valve and valve guide bush.

6. INSPECT INTAKE VALVE SEAT

   
   

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

   2. 

      *a

      Width

      Lightly press the intake valve face against the intake valve seat.

      Tech Tips

      Do not rotate the intake valve while pressing the intake valve.

   3. Check the intake valve face and intake valve seat.

      
      

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

         If not, correct the intake valve seat.

7. INSPECT EXHAUST VALVE SEAT

   
   

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

   2. 

      *a

      Width

      Lightly press the exhaust valve face against the exhaust valve seat.

      Tech Tips

      Do not rotate the exhaust valve while pressing the exhaust valve.

   3. Check the exhaust valve face and exhaust valve seat.

      
      

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

         If not, correct the exhaust valve seat.

8. INSPECT CAMSHAFT THRUST CLEARANCE

   
   

   1. Inspect the camshaft and No. 2 camshaft.

      
      

      1. Install the camshaft and No. 2 camshaft.

         Click here

      2. 

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

         Standard Thrust Clearance
         Item Specified Condition Camshaft 0.060 to 0.200 mm (0.00236 to 0.00787 in.) No. 2 Camshaft 0.060 to 0.155 mm (0.00236 to 0.00610 in.)

         Maximum Thrust Clearance
         Item Specified Condition Camshaft 0.215 mm (0.00846 in.) No. 2 Camshaft 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.