Cylinder Head Inspection

Cylinder head cover

1. 1
   Inspect for flatness. Using a precision straightedge and feeler gauge, measure the cylinder head and manifold mating surfaces for warpage. Cylinder head gasket surface flatness Standard: Less than 0.05 mm (0.0019 in) for overall surface. Less than 0.02 mm (0.0007 in) for a 100 mm (3.9370 in) x 100 mm (3.9370 in) area. Manifold mounting surface flatness (intake/exhaust) Standard: Less than 0.10 mm (0.0039 in)

   

2. 2
   Inspect for cracks. Check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks. If any cracks are found, replace the cylinder head.

Valve and Valve Spring

1. 1
   Inspect the valve stems and valve guides.

   1. Using a caliper gauge, measure the inside diameter of the valve guide. Valve guide inside diameter Intake/Exhaust: 5.500 ~ 5.512 mm (0.21654 ~ 0.21701 in)

      

   2. Using a micrometer, measure the valve stem diameter. Valve stem outside diameter Intake: 5.465 - 5.480 mm (0.21516 - 0.21575 in.) Exhaust: 5.458 - 5.470 mm (0.21498 - 0.21535 in.)

      

   3. Subtract the valve stem diameter from the valve guide inside diameter to calculate the stem-to-guide clearance. Valve stem-to-guide clearance [Standard] Intake: 0.020 ~ 0.047 mm (0.00078 ~ 0.00185 in) Exhaust: 0.030 ~ 0.054 mm (0.00118 ~ 0.00212 in) [Limit] Intake: 0.070 mm (0.00275 in) Exhaust: 0.090 mm (0.00354 in) If the clearance exceeds the maximum, replace the valve or cylinder head.
2. 2
   Inspect the valves.

   1. Make sure the valve face is ground to the correct valve face angle.
   2. Check the valve face for wear. If the valve face is worn, replace the valve.
   3. Check the valve head edge thickness. Valve head thickness (Margin) [Standard] Intake: 1.02 mm (0.0401 in) Exhaust: 1.09 mm (0.0429 in)

      

      If the margin thickness is less than the minimum, replace the valve.
   4. Check the valve length. Valve length [Standard] Intake: 113.18 mm (4.4559 in) Exhaust: 105.84 mm (4.1669 in) [Limit] Intake: 112.93 mm (4.4461 in) Exhaust: 105.59 mm (4.1571 in)
   5. Check the valve stem tip for wear. If the valve stem tip is worn, replace the valve.
3. 3
   Inspect the valve seats.

   1. Check the valve seat for signs of overheating and improper contact with the valve face. If necessary, replace the cylinder head.
   2. Inspect the valve guide for wear. If the valve guide is worn, replace the cylinder head.
4. 4
   Inspect the valve springs.

   1. Using a steel square, measure the valve spring squareness.
   2. Using a caliper, measure the free length of the valve spring. Valve spring [Standard] Free height: 47.44 mm (1.8677 in) Out-of-square: Less than 1.5°

      

      If the free length is not within specification, replace the valve spring.

MLA (Mechanical Lash Adjuster)

1. 1
   Inspect the MLA. Using a micrometer, measure the outside diameter of the MLA. MLA outside diameter Intake/Exhaust: 27.964 - 27.980 mm (1.1010 - 1.1016 in.)

   MLA outside diameter: 31.964 - 31.980 mm (1.2584 - 1.2590 in.)

2. 2
   Using a caliper gauge, measure the inside diameter of the MLA bore in the cylinder head. MLA bore inside diameter: 32.000 ~ 32.025 mm (1.2598 ~ 1.2608 in)
3. 3
   Subtract the MLA outside diameter from the MLA bore inside diameter to calculate the MLA-to-bore clearance. MLA-to-bore clearance [Standard]: 0.020 ~ 0.061 mm (0.00078 ~ 0.00240 in) [Limit]: 0.070 mm (0.00275 in)