CLEAN CYLINDER HEAD SUB-ASSEMBLY
Using a gasket scraper, remove all the gasket material from the surface of the cylinder head that contacts the cylinder block.
Note
Be careful not to scratch the surface of the cylinder head.
Using a soft brush and solvent, thoroughly clean the cylinder head.
Using a valve guide bushing brush and solvent, clean all the guide bushes.
INSPECT CYLINDER HEAD SUB-ASSEMBLY
| *a | Cylinder Block Side |
| *b | Intake Manifold Side |
| *c | Exhaust Manifold Side |
Inspect the cylinder head for warpage.
Using a precision straightedge and feeler gauge, measure the surfaces of the cylinder head that contact the cylinder block and manifolds for warpage.
| Maximum warpage |
|---|
| 0.15 mm (0.0059 in.) |
If the warpage is more than the maximum, replace the cylinder head sub-assembly.
Inspect the cylinder head for cracks.
Using a dye penetrant, check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks.
If there are cracks, replace the cylinder head sub-assembly.
CLEAN INTAKE VALVE
Using a gasket scraper, chip off any carbon from the valve head.
Using a wire brush, thoroughly clean the valve.
INSPECT INTAKE VALVE
Using a micrometer, measure the diameter of the valve stem.
| Standard valve stem diameter |
|---|
| 5.970 to 5.985 mm (0.2350 to 0.2356 in.) |
If the diameter is not as specified, replace the intake valve.
| *1 | Valve Face Angle |
Check the valve face angle.
Grind the valve enough to remove any pits and carbon.
Check that the valve is ground to the correct valve face angle.
| Standard valve face angle |
|---|
| 44.5° |
If the result is not as specified, replace the valve.
| *1 | Margin Thickness |
Check the valve head margin thickness.
| Standard margin thickness |
|---|
| 1.1 mm (0.043 in.) |
| Minimum margin thickness |
|---|
| 0.8 mm (0.032 in.) |
If the margin thickness is less than the minimum, replace the intake valve.
Check the overall valve length.
| Standard overall length |
|---|
| 105.15 to 105.75 mm (4.1398 to 4.1634 in.) |
| Minimum overall length |
|---|
| 104.65 mm (4.1201 in.) |
If the overall length is less than the minimum, replace the intake valve.
Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, resurface the tip with a grinder or replace the intake valve.
Note
Do not grind the valve so it becomes shorter than the minimum overall length.
CLEAN EXHAUST VALVE
Using a gasket scraper, chip off any carbon from the valve head.
Using a wire brush, thoroughly clean the exhaust valve.
INSPECT EXHAUST VALVE
Using a micrometer, measure the diameter of the valve stem.
| Standard valve stem diameter |
|---|
| 5.960 to 5.975 mm (0.2346 to 0.2352 in.) |
If the diameter is not as specified, replace the valve.
| *1 | Valve Face Angle |
Check the valve face angle.
Grind the valve enough to remove any pits and carbon.
Check that the valve is ground to the correct valve face angle.
| Standard valve face angle |
|---|
| 44.5° |
If the result is not as specified, replace the exhaust valve.
| *1 | Margin Thickness |
Check the valve head margin thickness.
| Standard margin thickness |
|---|
| 1.2 mm (0.047 in.) |
| Minimum margin thickness |
|---|
| 0.7 mm (0.028 in.) |
If the margin thickness is less than the minimum, replace the valve.
Check the overall valve length.
| Standard overall length |
|---|
| 105.02 to 105.62 mm (4.1347 to 4.1583 in.) |
| Minimum overall length |
|---|
| 104.52 mm (4.1150 in.) |
If the overall length is less than the minimum, replace the exhaust valve.
Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, resurface the tip with a grinder or replace the exhaust valve.
Note
Do not grind the valve so it becomes shorter than the minimum overall length.
INSPECT INNER COMPRESSION SPRING
| *1 | Deviation |
Using a steel square, measure the deviation of the spring.
| Maximum deviation |
|---|
| 2.0 mm (0.079 in.) |
If the deviation is more than the maximum, replace the inner compression spring.
Using a vernier caliper, measure the free length of the spring.
| Standard free length |
|---|
| 48.4 mm (1.906 in.) |
If the free length is not as specified, replace the inner compression spring.
Using a spring tester, measure the tension of the valve spring at the specified installed length.
| Standard tension (at 33.1 mm (1.303 in.)) |
|---|
| 175 to 193 N (17.9 to 19.6 kgf, 39.4 to 43.3 lbf) |
If the tension is not as specified, replace the inner compression spring.
INSPECT INTAKE VALVE GUIDE BUSH
Using a caliper gauge, measure the inside diameter of the valve guide bush.
| Standard valve guide bush inside diameter |
|---|
| 6.01 to 6.03 mm (0.2366 to 0.2374 in.) |
Subtract the valve stem diameter measurement (refer to the intake valve inspection procedures above) from the valve guide bush inside diameter measurement.
| Standard oil clearance |
|---|
| 0.025 to 0.060 mm (0.00010 to 0.0024 in.) |
| Maximum oil clearance |
|---|
| 0.08 mm (0.0031 in.) |
If the oil clearance is more than the maximum, replace the intake valve and intake valve guide bush.
INSPECT EXHAUST VALVE GUIDE BUSH
Using a caliper gauge, measure the inside diameter of the valve guide bush.
| Standard valve guide bush inside diameter |
|---|
| 6.01 to 6.03 mm (0.2366 to 0.2374 in.) |
Subtract the valve stem diameter measurement (refer to the exhaust valve inspection procedures above) from the valve guide bush inside diameter measurement.
| Standard oil clearance |
|---|
| 0.035 to 0.070 mm (0.0014 to 0.0028 in.) |
| Maximum oil clearance |
|---|
| 0.10 mm (0.0039 in.) |
If the oil clearance is more than the maximum, replace the valve and guide bush.
INSPECT INTAKE VALVE SEAT
| *1 | 45° Carbide Cutter |
Using a 45° carbide cutter, resurface the valve seats. Remove only enough metal to clean the valve seats.
| *1 | Width |
Apply a light coat of Prussian blue to the valve face.
Lightly press the valve face against the valve seat.
Note
Do not rotate the valve while pressing the valve against the valve seat.
Check the valve face and valve seat.
Check that the contact surfaces of the valve seat and valve face are in the middle area of their respective surfaces, with the width between 1.2 and 1.6 mm (0.047 and 0.063 in.).
If the contact surfaces are not as specified, resurface the valve intake seat. If necessary, replace the intake valve.
Check that the contact surfaces of the valve seat and valve face are even around the entire valve seat.
If the contact surfaces are not as specified, resurface the intake valve seat. If necessary, replace the intake valve.
INSPECT EXHAUST VALVE SEAT
| *1 | 45° Carbide Cutter |
Using a 45° carbide cutter, resurface the valve seats. Remove only enough metal to clean the valve seats.
| *1 | Width |
Apply a light coat of Prussian blue to the valve face.
Lightly press the valve face against the valve seat.
Note
Do not rotate the valve while pressing the valve against the valve seat.
Check the valve face and valve seat.
Check that the contact surfaces of the valve seat and valve face are in the middle area of their respective surfaces, with the width between 1.6 and 2.0 mm (0.063 and 0.079 in.)
If the contact surfaces are not as specified, resurface the exhaust valve seat. If necessary, replace the exhaust valve.
Check that the contact surfaces of the valve seat and valve face are even around the entire valve seat.
If the contact surfaces are not as specified, resurface the exhaust valve seat. If necessary, replace the exhaust valve.
INSPECT VALVE LIFTER
Using a micrometer, measure the lifter diameter.
| Standard lifter diameter |
|---|
| 30.966 to 30.976 mm (1.2191 to 1.2195 in.) |
Using a caliper gauge, measure the lifter bore diameter of the cylinder head.
| Standard lifter bore diameter |
|---|
| 31.000 to 31.021 mm (1.2205 to 1.2213 in.) |
Measure the oil clearance by subtracting the lifter diameter measurement from the lifter bore diameter measurement.
| Standard oil clearance |
|---|
| 0.024 to 0.055 mm (0.0009 to 0.0022 in.) |
| Maximum oil clearance |
|---|
| 0.095 mm (0.0037 in.) |
If the oil clearance is more than the maximum, replace the lifter. If necessary, replace the cylinder head.
INSPECT CAMSHAFT OIL CLEARANCE
Clean the bearing caps and journals.
Check the bearings for flaking and scoring.
If the bearings are damaged, replace the bearing caps and cylinder head as a set.
Place the camshaft on the cylinder head.
| *1 | Plastigage |
| *a | Intake Side |
| *b | Exhaust Side |
Lay a strip of Plastigage across each of the journals.
Install the bearing caps.
Note
Do not turn the camshaft.
Remove the bearing caps.
| *1 | Plastigage |
| *a | Intake Side |
| *b | Exhaust Side |
Measure the Plastigage at its widest point.
| Standard oil clearance |
|---|
| 0.025 to 0.062 mm (0.0010 to 0.0024 in.) |
| Maximum oil clearance |
|---|
| 0.1 mm (0.0039 in.) |
If the oil clearance is more than the maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
Completely remove the Plastigage.
Remove the camshaft.
INSPECT CAMSHAFT THRUST CLEARANCE
Install the camshaft.
| *a | Intake Side |
| *b | Exhaust Side |
Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.
| Standard thrust clearance |
|---|
| 0.035 to 0.185 mm (0.0014 to 0.073 in.) |
| Maximum thrust clearance |
|---|
| 0.25 mm (0.0098 in.) |
If the thrust clearance is more than the maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
Remove the camshaft.