Yanmar 6LPA-STP2 Service Manual page 103

Cylinder Head
12/05
4. Subtract the valve stem diameter from the
measured valve guide inner diameter.
Standard oil clearance:
• Intake valve: 0.025 to 0.060 mm
(0.001 to 0.002 in.)
• Exhaust valve: 0.035 to 0.070 mm
(0.001 to 0.002 in.)
Maximum oil clearance:
• Intake valve: 0.08 mm (0.003 in.)
• Exhaust valve: 0.10 mm (0.004 in.)
If the measured clearance exceeds the specified
maximum, replace the valve and cylinder head
assembly.
5. Check the valve face for wear. If the valve face
is worn, replace the valve.
6. Check the margin thickness of valve head
(Figure 5-29).
• Standard margin thickness: 1.00 mm
(0.014 in.)
• Minimum margin thickness: 0.83 mm
(0.033 in.)
If the measured margin thickness is below the
specified minimum, replace the valve.
Figure 5-29
(1)
Figure 5-29
1 – Margin Thickness
2 – Valve Face
6LPA Service Manual
7. Check the overall length of the intake and
exhaust valves (Figure 5-30).
Standard overall length:
• Intake valve: 126.85 to 127.45 mm
• Exhaust valve: 126.43 to 127.03 mm
Minimum overall length:
• Intake valve: 126.85 mm (4.994 in.)
• Exhaust valve: 126.43 mm (4.997 in.)
If the measured overall length is less than the
specified minimum, replace the valve. Check the
tip of valve stem for wear. If the valve stem tip is
worn, replace the valve.
Figure 5-30
1 – Overall Length
(2)
0004954
© 2007 Yanmar Marine International
(4.994 to 5.017 in.)
(4.977 to 5.001 in.)
(1)
Figure 5-30
ENGINE
0004955
5-23