Yanmar 6LY3 series Service Manual page 98

ENGINE
Inspecting the Valve Guide Projection
The valve guide should extend the specified
distance above the top of the cylinder head
(Figure 5-26).
Figure 5-26
(1)
Figure 5-26
1 – Exhaust Valve
2 – Intake Valve
Inspecting the Valve Stem Seals
The valve stem seals on the intake / exhaust valve
guides cannot be reused. Replace used seals with
new ones.
Lubricate the valve stems before installing the new
stem seals on the intake (Figure 5-26, (2)) and
exhaust valves (Figure 5-26, (1)). Exhaust stem
seals are marked yellow. Intake stem seals are not
marked.
Installing the Valve Stem Seal
1. Place a tool stop against the cylinder head; over
the valve stem (Figure 5-27, (1)).
2. Place the valve stem seal (Figure 5-27, (4)) on
the guide pin (Figure 5-27, (2)).
3. Place the guide pin and seal on the valve stem.
Check that the spring (Figure 5-27, (3)) is still
in position on the seal.
4. Use the valve stem seal installer tool to install
the seal. Tap the seal in position using a tool
stop (Figure 5-27, (6)) to prevent damage to
the valve stem seal.
5-32
Inspecting the Cylinder Block and Components
(2)
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© 2007 Yanmar Marine International
5. Remove the tools and verify that the seal is
against the top of the valve guide
(Figure 5-27, (5)).
Figure 5-27
Figure 5-27
1 – Valve Stem Seal Installer
2 – Guide Pin
3 – Seal Spring
4 – Valve Stem Seal
5 – Seal Against Top of Valve Guide
6 – Tool Stop
Checking the Valve Springs
1. Check the valve spring for scratches or
corrosion.
Figure 5-28
Figure 5-28
2. Measure the free length of the spring.
6LY3 Service Manual
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(2)
(3)
(4)
(5)
(6)
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