Cylinder Head Assembly: Testing and Inspection

1. Remove scale, sealing compound and carbon deposits. After cleaning oil passages, apply compressed air to make certain that the passages are not clogged.
2. Visually check the cylinder head for cracks, damage or water leakage.





3. Check the cylinder head surface for flatness with a straight edge and feeler as shown in illustration.

Standard value: Max. 0.05 mm (0.002 inch)
Limit: 0.20 mm (0.008 inch)

Valve Guides





Check the valve stem-to-guide clearance. If the clearance exceeds the service limit, replace the valve guide with a new oversize guide.

Valve stem-to-guide clearance:
Standard valve:
Intake: 0.03 - 0.06 mm (0.0012 - 0.0024 inch)
Exhaust: 0.05 - 0.09 mm (0.0020 - 0.0035 inch)
Limit:
Intake: 0.10 mm (0.0039 inch)
Exhaust: 0.15 mm ( 0.0059 inch)

Valve





1. Replace the valve stem if it is worn (stepped, worn or damaged). Also replace if the stem end (the surface contacting the auto-lash adjuster) is recessed.
2. Check the valve face contact area, and recondition or replace as necessary.





3. Replace the valve if the width of the margin (thickness of the valve head) is less than the minimum specified.

Valve Margin:
Standard value:
Intake side: 1.2 mm (0.047 inch)
Exhaust side: 2.0 mm (0.079 inch)
Limit:
Intake side: 0.7 mm (0.028 inch)
Exhaust side: 1.5 mm (0.059 inch)

Valve Spring





1. Check free height of each valve spring and replace if necessary.
2. Using a square, test the squareness of each valve spring. If a spring is excessively out of square, replace it.

Valve Spring:
Standard value:
Free height: 50.5 mm (1.988 inch)
Load: 32.9kg/40.4 mm (74 lbs./1.591 inch)
Out of squareness: Max. 2°
Limit:
Free height: 49.5 mm (1.949 inch)
Load: 32.9kg/41.4 mm (74 lbs./1.630 inch)
Out of squareness: Max. 40°