CYLINDER HEAD INSPECTION

PROCEDURE

1. INSPECT CYLINDER HEAD FOR FLATNESS

   
   

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

      

      *a	Bottom Side	*b	Intake Manifold Side
      *c	Exhaust Manifold Side	-	-

      Maximum Warpage
      Item Specified Condition Bottom 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.)

      Tech Tips

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

2. INSPECT CYLINDER HEAD FOR CRACKS

   
   

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

      Tech Tips

      If cracks are found, replace the cylinder head sub-assembly.

3. INSPECT INTAKE VALVE

   
   

   1. 

      *a	Overall Length

      Using a vernier caliper, measure the valve overall length.

      Standard Overall Length
      109.34 mm (4.30 in.)

      Minimum Overall Length
      108.84 mm (4.29 in.)

      Tech Tips

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

   2. 

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

      Standard Valve Stem Diameter
      5.470 to 5.485 mm (0.215 to 0.216 in.)

      Tech Tips

      If the diameter is not as specified, check the oil clearance.

   3. 

      *a	Margin Thickness

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

      Standard Margin Thickness
      1.0 mm (0.0394 in.)

      Minimum Margin Thickness
      0.5 mm (0.0197 in.)

      Tech Tips

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

4. INSPECT EXHAUST VALVE

   
   

   1. 

      *a	Overall Length

      Using a vernier caliper, measure the valve overall length.

      Standard Overall Length
      108.25 mm (4.26 in.)

      Minimum Overall Length
      107.75 mm (4.24 in.)

      Tech Tips

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

   2. 

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

      Standard Valve Stem Diameter
      5.465 to 5.480 mm (0.215 to 0.216 in.)

      Tech Tips

      If the diameter is not as specified, check the oil clearance.

   3. 

      *a	Margin Thickness

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

      Standard Margin Thickness
      1.0 mm (0.0394 in.)

      Minimum Margin Thickness
      0.5 mm (0.0197 in.)

      Tech Tips

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

5. INSPECT INNER COMPRESSION SPRING

   
   

   1. 

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

      Standard free length
      51.88 mm (2.042 in.) or 51.90 mm (2.043 in.)

      Note

      Inner compression springs come in 2 different lengths. Make sure all inner compression springs are the same length when replacing them.

      Tech Tips

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

   2. 

      *1	Deviation
      *a	37.5 mm (1.48 in.)

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

      Maximum deviation
      1.3 mm (0.0512 in.)

      Tech Tips

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

6. INSPECT VALVE GUIDE BUSH OIL CLEARANCE

   
   

   1. 

      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.)

   2. 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 0.085 mm (0.00335 in.)

      Tech Tips

      
      

      • Oil clearance = Inside diameter - Valve stem diameter

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

7. INSPECT INTAKE VALVE SEAT

   
   

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

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

      Tech Tips

      Do not rotate the valve while pressing the valve.

   3. 

      *a

      Width

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

      
      

      1. If Prussian blue appears around the entire valve face, the valve face is concentric. If not, replace the intake valve.

      2. If Prussian blue appears around the entire intake valve seat, the intake valve seat and valve face are concentric. If not, resurface the intake valve seat.

      3. Check that the intake valve seat contacts the middle of the valve face with the width between 1.0 and 1.4 mm (0.0394 and 0.0551 in.).

8. INSPECT EXHAUST VALVE SEAT

   
   

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

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

      Tech Tips

      Do not rotate the valve while pressing the valve.

   3. 

      *a

      Width

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

      
      

      1. If Prussian blue appears around the entire valve face, the valve face is concentric. If not, replace the exhaust valve.

      2. If Prussian blue appears around the entire exhaust valve seat, the exhaust valve seat and valve face are concentric. If not, resurface the exhaust valve seat.

      3. Check that the exhaust valve seat contacts the middle of the valve face with the width between 1.0 and 1.4 mm (0.0394 and 0.0551 in.).