Cylinder Head Assembly: Testing and Inspection
CYLINDER HEAD ASSEMBLYINSPECTION
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 valve stems and valve guides.
1) Using a caliper gauge, measure the inside diameter or the valve guide.
2) Using a micrometer, measure the diameter of the valve stem.
3) Subtract the valve stem diameter measurement from the valve guide inside diameter measurement.
Valve stem-to-guide clearance
[Standard]
Intake: 0.02 - 0.05 mm (0.0008 - 0.0020 inch)
Exhaust: 0.035 - 0.065 mm (0.0014 - 0.0026 inch)
[Limit] Intake: 0.1 mm (0.004 inch.)
Exhaust: 0.13 mm (0.00511 inch)
If the clearance is greater than maximum, replace the valve and valve guide.
2. Inspect valves.
1) Check the valve is ground to the correct valve face angle.
2) Check that the surface of the 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 the valve stem tip for wear. If the valve stem tip is worn, replace the valve.
3. Inspect valve seats
Check the valve seat for evidence of overheating and improper contact with the valve face.
Replace the seat if necessary.
Before reconditioning the seat, check the valve guide for wear. If the valve guide is worn, replace it, then recondition the seat. 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 valve springs.
1) Using a steel square, measure the out-of-square of the valve spring.
2) Using a vernier calipers, measure the free length of the valve spring.
If the free length is not as specified, replace the valve spring.
CAMSHAFT
1. Inspect cam lobes. Using a micrometer, measure the cam lobe height.
If the cam lobe height is less than minimum, replace the camshaft.
2. Inspect 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.
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 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 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 maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.
3) Remove the camshafts.
CVVT ASSEMBLY
1. Inspect CVVT assembly.
1) Check that the CVVT assembly will not turn.
2) Apply vinyl tape to all the parts except the one indicated by the arrow in the illustration.
3) Wind tape around the tip of the air gun and apply air of approximately 100 kPa (1 kgf/cm2, 14 psi) to the port of the camshaft. (Perform this order to release the lock pin for the maximum delay angle locking.)
NOTE: When the oil splashes, wipe it off with a shop rag and the likes.
4) Under the condition of (3), turn the CVVT assembly to the advance angle side (the arrow marked direction in the illustration) with your hand.
Depending on the air pressure, the CVVT assembly will turn to the advance side without applying force by hand. Also, under the condition that the pressure can be hardly applied because of the air leakage from the port, there may be the case that the lock pin could be hardly released.
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 200
6) Turn the CVVT assembly with your hand and lock it at the maximum delay angle position.