Cylinder Head Assembly: Testing and Inspection
INSPECTIONCYLINDER HEAD
1. 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
Standard: Less than 0.03 mm (0.0012 inch)
Limit: 0.05 mm (0.0020 inch)
Flatness of manifold mating surface
Standard: Less than 0.15 mm (0.0059 inch)
Limit: 0.30 mm (0.0118 inch)
2. Inspect for cracks.
Check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks. If cracked, replace the cylinder head.
VALVE AND VALVE SPRING
1. Inspect the valve stems and valve guides.
1) Using a caliper gauge, measure the inner diameter of valve guide.
Valve guide inner diameter: 6.000 - 6.015 mm (0.2362 - 0.2368 inch)
2) Using a micrometer, measure the outer diameter of valve stem.
Valve stem outer diameter
Intake: 5.965 - 5.980 mm (0.2348 - 0.2354 inch)
Exhaust: 5.950 - 5.965 mm (0.2343 - 0.2348 inch)
3) Subtract the valve stem outer diameter measurement from the valve guide inner diameter measurement.
Valve stem-to-guide clearance
Standard
Intake: 0.020 - 0.050 mm (0.0008 - 0.0020 inch)
Exhaust: 0.035 - 0.065 mm (0.0014 - 0.0026 inch)
Limit
Intake: 0.10 mm (0.0039 inch)
Exhaust: 0.13 mm (0.0051 inch)
If the clearance is greater than maximum, replace the valve and valve guide.
2. Inspect the valves.
1) Check the valve is ground to the correct valve face angle.
2) Check the surface of the valve face for damage or wear.
If the valve face is damaged or worn, replace the valve.
3) Check the valve head margin thickness.
If the margin thickness is less than minimum, replace the valve.
Margin
Standard
Intake: 1.15 mm (0.0453 inch)
Exhaust: 1.35 mm (0.0531 inch)
Limit
Intake: 0.8 mm (0.0315 inch)
Exhaust: 1.0 mm (0.0394 inch)
4) Check the surface of valve stem tip for wear.
If the valve stem tip is worn, replace the valve.
3. Inspect the valve seats.
1) Check the valve seat for evidence of overheating and improper contact with the valve face.
Replace the seat if necessary.
2) Before reconditioning the seat, check the valve guide for wear. If the valve guide is worn, replace it, then recondition the seat.
3) Recondition the valve seat with a valve seat grinder or cutter. The valve seat contact width should be within specifications and centered on the valve face.
4. Inspect the valve springs.
1) Using a steel square, measure the out-of-square of valve spring.
2) Using vernier calipers, measure the free length of valve spring.
Valve spring
Standard
Free height: 48.86 mm (1.9236 inch)
Load: 18.8 ± 0.9 kg / 39.0 mm (41.4 ± 2.0 lb / 1.5354 inch) 41.0 ± 1.5 kg / 30.5 mm (90.4 ± 3.3 lb / 1.2008 inch)
Out of square: Less than 1.5°
Limit Out of square: 3°
If the loads is not as specified, replace the valve spring.
CAMSHAFT
1. Inspect the cam lobes.
Using a micrometer, measure the cam lobe height.
If the cam lobe height is less than minimum, replace the camshaft.
Cam height
Intake: 44.518 - 44.718 mm (1.7527 - 1.7605 inch)
Exhaust: 44.418 - 44.618 mm (1.7487 - 1.7566 inch)
2. Inspect the camshaft journal clearance.
1) Clean the bearing caps and camshaft journals.
2) Place the camshafts on the cylinder head.
3) Lay a strip of plastigage across each of the camshaft journal.
4) Install the bearing caps and tighten the bolts with specified torque.
CAUTION: Do not turn the camshaft.
5) Remove the bearing caps.
6) Measure the plastigage at its widest point.
Bearing oil clearance
Standard: 0.020 - 0.061 mm (0.0008 - 0.0024 inch)
Limit: 0.1 mm (0.0039 inch)
If the oil clearance is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
7) Completely remove the plastigage.
8) Remove the camshafts.
3. Inspect the camshaft end play.
1) Install the camshafts.
2) Using a dial indicator, measure the end play while moving the camshaft back and forth.
Camshaft end play
Standard: 0.1 - 0.2 mm (0.0039 - 0.0079 inch)
If the end play is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and
cylinder head as a set.
3) Remove the camshafts.