Inspection After Disassembly

CYLINDER HEAD


Inspection After Disassembly


VALVE DIMENSIONS
- Check the dimensions of each valve. For the dimensions, refer to EM-272, "Standard and Limit".





- If the dimensions are out of the standard, replace valve and check the valve seat contact. Refer to "VALVE SEAT CONTACT".

VALVE GUIDE CLEARANCE

Valve Stem Diameter
Measure the diameter of valve stem with micrometer.






Standard
Intake : 5.972 - 5.980 mm (0.2351 - 0.2354 in)
Exhaust : 5.962 - 5.970 mm (0.2347 - 0.2350 in)


Valve Guide Inner Diameter
Measure the inner diameter of valve guide with bore gauge.

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


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

Valve guide clearance:
Standard
Intake : 0.020 - 0.046 mm (0.0008 - 0.0018 in)
Exhaust : 0.030 - 0.056 mm (0.0012 - 0.0022 in)
Limit
Intake : 0.08 mm (0.0031 in)
Exhaust : 0.1 mm (0.004 in)

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

VALVE GUIDE REPLACEMENT
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 to 130�C (230 to 266�F) by soaking in heated oil.
2. Drive out valve guide with a press [under a 20 kN (2 ton, 2.2 US ton, 2.0 Imp ton) pressure] or hammer and valve guide drift





(commercial service tool).

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





3. Using valve guide reamer (commercial service tool), ream cylinder head valve guide hole.

Valve guide hole diameter (for service parts):
Intake and exhaust : 10.175 - 10.196 mm (0.4006 - 0.4014 in)






4. Heat cylinder head to 110 to 130�C (230 to 266�F) by soaking in heated oil.
5. Using valve guide drift (commercial service tool), press valve guide from camshaft side to the dimensions as in the figure.






WARNING:
Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
6. Using valve guide reamer (commercial service tool), apply reamer finish to valve guide.






Standard:
Intake and exhaust : 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 the specifications, perform this procedure.
- Apply prussian blue (or white lead) 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 "NG" conditions even after the recheck, replace valve seat. Refer to "VALVE SEAT REPLACEMENT".

VALVE SEAT REPLACEMENT
When valve seat is removed, replace with oversized [0.5 mm (0.020 in)] valve seat.
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. Refer to [1][2]Specifications.

CAUTION:
Prevent to scratch cylinder head by excessive boring.





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

Oversize [0.5 mm (0.020 in)]
Intake : 37.500 - 37.516 mm (1.4764 - 1.4770 in)
Exhaust : 32.700 - 32.716 mm (1.2874 - 1.2880 in)

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





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

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

CAUTION:
Avoid directly touching cold valve seats.





5. Using valve seat cutter set (commercial service tool) or valve seat grinder, finish seat to the specified dimensions. Refer to [1][2]Specifications.

CAUTION:
When using valve seat cutter, firmly grip cutter handle with both hands. Then, press on the contacting surface all around the circumference to cut in a single drive. Improper pressure on with cutter or cutting many different times may result in stage valve seat.
6. Using compound, grind to adjust valve fitting.
7. Check again for normal contact. Refer to "VALVE SEAT CONTACT".

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





Measure the maximum clearance between the top face of spring and try square.

Limit : 2.0 mm (0.079 in)

- If it exceeds the limit, replace valve spring.

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






Standard:
Intake and exhaust
Free height : 46.35 - 46.85 mm (1.8248 - 1.8445 in)
Installation height : 33.8 mm (1.331 in)
Installation load : 165 - 189 N (16.8 - 19.3 kg, 37 - 42 lb)
Height during valve open : 24.4 mm (0.961 in)
Load with valve open : 290 - 330 N (29.6 - 33.7 kg, 65 - 74 lb)

- If the installation load or load with valve open is out of the standard, replace valve spring.