CYLINDER HEAD INSPECTION

PROCEDURE

1. INSPECT CYLINDER HEAD SUB-ASSEMBLY

   
   

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

      

      Text in Illustration

      *a	Cylinder Block Sub-assembly Side	*b	Exhaust Side
      *c	Intake Side	-	-

      Maximum Warpage
      Item Specified Condition Cylinder Block Sub-assembly Side 0.05 mm (0.00197 in.) Intake Side 0.10 mm (0.00394 in.) Exhaust 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 INNER COMPRESSION SPRING

   
   

   1. 

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

      Standard free length
      47.38 mm (1.87 in.)

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

   2. 

      Text in Illustration

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

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

      Maximum deviation
      1.05 mm (0.0413 in.)

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

3. INSPECT INTAKE VALVE

   
   

   1. Clean the valves.

      
      

      1. Using a gasket scraper, chip off any carbon from the intake valve head.

      2. Using a wire brush, thoroughly clean the intake valve.

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

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

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

   3. 

      Text in Illustration

      *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.)

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

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

      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. Clean the valves.

      
      

      1. Using a gasket scraper, chip off any carbon from the exhaust valve head.

      2. Using a wire brush, thoroughly clean the exhaust valve.

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

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

      Tech Tips

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

   3. 

      Text in Illustration

      *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.)

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

   4. 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 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 0.08 mm (0.00315 in.) Exhaust 0.10 mm (0.00394 in.)

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

6. INSPECT VALVE SPRING SEAT

   
   

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

   2. 

      Text in Illustration

      *a

      Width

      Lightly press the valve face against the valve spring seat.

      Note

      Do not rotate the valve.

   3. Check the valve face and valve spring seat.

      
      

      1. Check that the contact surfaces of the valve spring seat and valve face are in the middle area of their respective surfaces, with the width between 1.1 and 1.5 mm (0.0433 and 0.0591 in.).

         If not, correct the valve spring seat.

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

         If not, correct the valve spring seat.

7. INSPECT CAMSHAFT THRUST CLEARANCE

   
   

   1. Clean the bearing caps, camshaft housing sub-assembly and camshaft journals.

   2. Place the camshafts on the camshaft housing sub-assembly.

   3. Install the camshaft bearing caps Click here.

   4. Install the camshaft housing sub-assembly to the cylinder head sub-assembly Click here.

   5. 

      Using a dial indicator, measure the camshaft 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 camshaft thrust clearance is more than the maximum, replace the camshaft housing sub-assembly.

      If the thrust surface is damaged, replace the camshaft.