Cylinder Head Assembly: Testing and Inspection

INSPECTION

CYLINDER 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.





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.





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





3) Subtract the valve stem outer diameter measurement from the valve guide inner diameter measurement.

Valve stem-to-guide clearance
Standard
Intake: 0.02 - 0.05mm (0.0008 - 0.0020in)
Exhaust: 0.035 - 0.065mm (0.0014 - 0.0026in)
Limit
Intake: 0.10mm (0.0039in)
Exhaust: 0.15mm (0.0059in)

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 valve for wear. If the valve face is worn, replace the valve.
3) Check the valve head margin thickness. If the margin thickness is less than minimum, replace the valve.





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 a vernier calipers, measure the free length of valve spring.





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 specified, replace the camshaft.
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.





If the oil clearance is greater than specified, 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.





If the end play is greater than specified, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
3) Remove the camshafts.

CVVT(CONTINUOUS VARIABLE VALVE TIMING) ASSEMBLY

1. Inspect the CVVT (Continuous Variable Valve Timing) assembly.
1) Check that the CVVT (Continuous Variable Valve Timing) assembly will not turn.
2) Apply vinyl tape to all the parts except the one indicated by the arrow in the illustration.





3) Wrap tape around the tip of the air gun and apply air of approximately 98kpa (1kg/cm2, 14psi) to the port of the camshaft.
Perform this order to release the lock pin for the maximum delay angle locking.)

NOTE: Wrap around it with a shop rag and the likes, because the oil splashes.

4) Under the condition of 3), turn the CVVT assembly to the advance angle side with your hand.
^ Depending on the air pressure, the CVVT assembly will turn to the advance side.
^ If air is leaking from the port and air pressure cannot be maintained, the locking pin will not release.





5) Except the position where the lock pin meets at the maximum delay angle, let the CVVT assembly turn back and forth and check the movable range and that there is no disturbance.

Standard: Movable smoothly in the range about 20°

6) Turn the CVVT assembly with your hand and lock it at the maximum delay angle position.

HLA (HYDRAULIC LASH ADJUSTER)

With the HLA filled with engine oil, hold A and press B by hand. If B moves, replace the HLA.