Inspection

CYLINDER HEAD


Inspection After Disassembly


CYLINDER HEAD DISTORTION
- Clean the surface of the cylinder head. Use a reliable straightedge and feeler gauge to check the flatness of cylinder head surface.





- Check along six positions as shown.





- If beyond the specified limit, resurface or replace it.
- The limit for cylinder head resurfacing is determined by the cylinder block resurfacing.










- After resurfacing cylinder head, check that camshaft rotates freely by hand. If resistance is felt, cylinder head must be replaced.

Nominal cylinder head height (H) : 126.3 - 126.5 mm (4.972 - 4.980 in)

VALVE DIMENSIONS
Check dimensions of each valve, refer to Maintenance.






VALVE GUIDE CLEARANCE
1. Measure valve deflection as shown. (Valve and valve guide mostly wear in this direction.)










2. If it exceeds the limit, check valve to valve guide clearance.
a. Measure valve stem diameter and valve guide inner diameter.





b. Check that clearance is within specification.






c. If it exceeds the limit, replace valve or valve guide.

VALVE GUIDE REPLACEMENT

NOTE:
When valve guide is removed, replace with oversized [0.2 mm (0.008 in)] valve guide.





1. To remove valve guide, heat cylinder head to 110� - 130�C (230� - 266�F) by soaking in heated oil.

WARNING:
Cylinder head is hot. Wear protective equipment to prevent getting burned.





2. Drive out the valve guide with a press [under a 20 kn (2.2 US ton) pressure] or hammer and suitable tool.
3. Ream cylinder head valve guide hole using suitable reamer.










4. Heat cylinder head to 110� - 130�C (230� - 266�F) by soaking in heated oil and press new valve guide from camshaft side into the cylinder head to the dimensions as shown.






WARNING:
Cylinder head is hot. Wear protective equipment to prevent getting burned.

Projection (L) : 12.6 - 12.8 mm (0.496 - 0.504 in)






5. Apply a reamer finish to the valve guide, using suitable reamer.

Intake and exhaust finished size : 6.000 - 6.018 mm (0.2362 - 0.2369 in)


VALVE SEAT CONTACT
- After confirming that the dimensions of valve guides and valves are within specifications, perform this procedure.





- Apply prussian blue onto contacting surface of valve seat to check the condition of the valve contact on the surface.
- Check if the contact area band is continuous all around the circumference.
- If not, grind to adjust valve fitting and check again. If the contacting surface still has N.G conditions even after the re-check, replace valve seat.

VALVE SEAT REPLACEMENT
1. Bore out old seat until it collapses. Boring should not continue beyond the bottom face of the seat recess in cylinder head. Set the machine depth stop to ensure this.





2. Ream cylinder head recess for service valve seat.





- Be sure to ream in circles concentric to the valve guide center.
- This will enable valve seat to fit correctly.
3. Heat cylinder head to 110� - 130�C (230� - 266�F) by soaking in heated oil.

WARNING:
Cylinder head is hot. Wear protective equipment to prevent getting burned.
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool to the specified dimensions. Refer to Maintenance.
6. After cutting, lap valve seat with abrasive compound.
7. Check valve seating condition.















8. Use a depth gauge to measure the distance between the mounting surface of the cylinder head spring seat and the valve stem end. If the distance is shorter than specified, repeat step 5 to adjust it. If it is longer, replace the valve seat with a new one.




VALVE SPRING SQUARENESS
Set try square along the side of valve spring and rotate the spring.





Measure the maximum clearance between the top face of spring and try square.
Out-of-square limit : Less than 2.0 mm (0.079 in)

VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD
Check valve spring pressure at specified spring height.









If it is not within specifications, replace the spring.

ASSEMBLY
1. Install valve guide. Follow the "VALVE GUIDE REPLACEMENT" procedure.
2. Install valve seat. Follow the "VALVE SEAT REPLACEMENT" procedure.





3. Install new valve spring seats and new valve oil seals using Tool.

Tool number : (J-39386)

- Install with valve oil seal drift to match dimension in illustration.

NOTE:
Dimension (H): Height measured before valve spring seat installation.

Height (H)
Intake and exhaust : 14.3 - 14.9 mm (0.563 - 0.587 in)

4. Install the valves in their original position, as marked during disassembly.





5. Install valve spring (uneven pitch type).
- Install smaller pitch end (paint mark) to cylinder head side (valve spring seat side).
6. Install valve spring retainer.










7. Install valve collet.





- Compress valve spring using Tool and install valve collet.
- Tap stem edge lightly with plastic hammer after installation to check its installed condition.
8. Install valve lifter.





9. Install spark plug tube as follows:
a. Remove old liquid gasket from all cylinder head holes.
b. Apply liquid gasket to area within approximately 12 mm (0.47 in) from edge of spark plug tube press fit side.
- Use Genuine RTV Silicone Sealant or equivalent. Refer to Recommended Chemical Products and Sealants.
c. Press fit the spark plug tube so that it height (H) is as specified, using suitable tool.

Standard press fit height (H) : 38.55 - 38.65 mm (1.5177 - 1.5217 in)

CAUTION:
- When press fitting, take care not to deform spark plug tube.
- After press fitting, wipe off liquid gasket protruding onto cylinder head upper face.
10. Install spark plug with spark plug wrench.