Inspect for flatness.
Using a precision straight edge and feeler gauge, measure the surface the contacting the cylinder block and the manifolds for warpage.
Flatness of cylinder head gasket surface
Less than 0.05 mm (0.0020 in.) for total area
Less than 0.02 mm (0.0008 in.) for a section of 100 mm (3.9370 in.) X 100 mm (3.9370 in.)
Inspect for cracks.
Check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks. If cracked, replace the cylinder head.
Inspect the valve stems and valve guides.
Using a caliper gauge, measure the inner diameter of valve guide.
Valve guide inner diameter :
5.500 ~ 5.512 mm (0.2165 ~ 0.2170 in)
Using a micrometer, measure the outer diameter of valve stem.
Valve stem outer diameter
Intake : 5.465 ~ 5.480 mm (0.2152 ~ 0.2157 in)
Exhaust : 5.458 ~ 5.470 mm (0.2149 ~ 0.2154 in)
Subtract the valve stem outer diameter measurement from the valve guide inner diameter measurement.
Valve stem- to-guide clearance
Intake : 0.020 ~ 0.047 mm (0.0008 ~ 0.0019 in)
Exhaust : 0.030 ~ 0.054 mm (0.0012 ~ 0.0021 in)
If the clearance is greater than specification, replace the valve or the cylinder head.
Inspect the valves.
Check the valve is ground to the correct valve face angle.
Check that the surface of valve for wear.
If the valve face is worn, replace the valve.
Check the valve head margin thickness.
If the margin thickness is less than minimum, replace the valve.
Margin
Standard
Intake : 1.1 mm (0.0433 in)
Exhaust : 1.26 mm (0.0496 in)
Check the length of valve.
Valve length
Standard
Intake : 93.15 mm (3.6673 in)
Exhaust : 92.60 mm (3.6457 in)
Check the surface of valve stem tip for wear.
If the valve stem tip is worn, replace the valve.
Inspect the valve seats and guide.
Check the valve seat for evidence of overheating and improper contact with the valve face. If the valve seat is worn, replace the cylinder head.
Check the valve guide for wear. If the valve guide is worn, replace the cylinder head.
Inspect the valve springs.
Using a steel square, measure the out-of-square of valve spring.
Using a vernier calipers, measure the free length of valve spring.
Valve spring
Standard
Free height : 45.1 mm (1.7755 in)
Out of square : Less than 1.5˚
