Inspection After Disassembly

CYLINDER HEAD


Inspection After Disassembly


CYLINDER HEAD DISTORTION
1. Remove any oil, scale, gasket, sealant and carbon deposits from the cylinder head surface.

CAUTION:
Do not allow any debris to enter the oil or coolant passages.





2. Measure the bottom surface of the cylinder head for distortion in six directions as shown, using suitable tools.

Standard : 0.03 mm (0.0012 in)
Limit : 0.1 mm (0.004 in)

- If measurement exceeds the limit, replace the cylinder head.

VALVE DIMENSIONS
- Check the dimensions of each valve. Refer to Specifications.





- If the dimensions are out of the standard, replace the valve.

VALVE GUIDE CLEARANCE

Valve Stem Diameter
Measure the diameter of the valve stem using suitable tool.





Standard
Intake : 5.965 - 5.980 mm (0.2348 - 0.2354 in)
Exhaust : 5.955 - 5.970 mm (0.2344 - 0.2350 in)

Valve Guide Inside Diameter
Measure the inside diameter of the valve guide using suitable tool.

Standard
Intake and Exhaust : 6.000 - 6.018 mm (0.2362 - 0.2369 in)

Valve Guide Clearance
- (Valve guide clearance) = (Valve guide inside diameter) � (Valve stem diameter).

Valve guide clearance:
Standard
Intake : 0.020 - 0.053 mm (0.0008 - 0.0021 in)
Exhaust : 0.030 - 0.063 mm (0.0012 - 0.0025 in)
Limit
Intake : 0.08 mm (0.0031 in)
Exhaust : 0.09 mm (0.0035 in)

- If the calculated value exceeds the limit, replace valve and/or valve guide. When the valve guide must be replaced, follow the "VALVE GUIDE REPLACEMENT" procedure.

VALVE GUIDE REPLACEMENT
When the valve guide is removed, replace it with an oversized (0.2 mm, 0.008 in) valve guide.





1. To remove the valve guide, heat the cylinder head to 110°C (230° to 266°F) by soaking it in heated oil.
2. Remove the valve guide using suitable tool.





CAUTION:
Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
3. Ream the cylinder head valve guide hole using suitable tool.





Valve guide hole diameter:
Standard
Intake and exhaust : 9.975 - 9.996 mm (0.3927 - 0.3935 in)
Oversize (service)
Intake and exhaust : 10.175 - 10.196 mm (0.4006 - 0.4014 in

4. Heat the cylinder head to 110° to 130°C (230° to 266°F) by soaking it in heated oil.





5. Press the valve guide from the camshaft side to the dimensions as shown.

CAUTION:
Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.





6. Ream the cylinder head valve guide using suitable tool.

Valve guide inside diameter:
Intake and exhaust : 6.000 - 6.018 mm (0.2362 - 0.2369 in)






VALVE SEAT CONTACT
- After confirming that the dimensions of the valve guides and valves are within specifications, perform this procedure.
- Apply Prussian blue (or white lead) onto the contacting surface of the 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 the valve fit and check again. If the contacting surface still has NG conditions even after the re-check, replace the valve seat.

VALVE SEAT REPLACEMENT
When the valve seat is removed, replace it with oversized (0.5 mm, 0.020 in) valve seat.
1. Bore out the old seat until it collapses. Boring should not continue beyond the bottom face of the seat recess in the cylinder head. Set the machine depth stop to ensure this.





2. Ream the cylinder head recess diameter for service valve seat.

Oversize [0.5 mm (0.020 in)] (Service):
Intake : 38.500 - 38.516 mm (1.5157 - 1.5164 in)
Exhaust : 32.700 - 32.716 mm (1.2874 - 1.2880 in)

- Be sure to ream in circles concentric to the valve guide center.
- This will enable valve seat to fit correctly.





3. Heat the cylinder head to 110° to 130°C (230° to 266°F) by soaking it in heated oil.
4. Cool the valve seats well with dry ice. Force fit the valve seat into the cylinder head.

CAUTION:
- Avoid directly touching cold valve seats.
- Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.





5. Finish the seat to the specified dimensions using suitable tool.
Follow the "VALVE SEAT CONTACT" procedure.

CAUTION:
When using valve seat cutter, firmly grip the cutter handle with both hands. Then, press on the contacting surface all around the circumference to cut in a single drive. Improper pressure on the cutter or cutting many different times may result in stage valve seat.





6. Grind to obtain the dimensions indicated as shown.
- Using compound, grind to adjust valve fitting.





7. Check again for normal contact. Follow the "VALVE SEAT CONTACT" procedure.

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.

Limit : Less than 2.2 mm (0.087 in)

- If measurement is not within specifications, replace the valve spring.

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





Standard:
Intake and exhaust
Free height: 50.58 mm (1.9913 in)
Installation height: 37.0 mm (1.457 in)
Installation pressure: 165.8 - 187.0 N (16.9 - 19.1 kg, 37- 42 lb)
Height during valve open: 28.2 mm (1.110 in)
Load with valve open: 314.8 - 355.0 N (32.1 - 36.2 kg, 71 - 80 lb

- If measurement is not within specifications, replace the valve spring.