ENGINE
Inspecting the Cylinder Block and Components
12/05
6LY3 Service Manual
5-35
© 2007 Yanmar Marine International
Measuring Piston Top Clearance
• Place a high-quality fuse wire (Figure 5-33, (2))
(Ø1.2 mm (0.047 in.), 10 mm (0.393 in.) long in
four positions on the top of the piston
(Figure 5-33, (3)).
Figure 5-33
Figure 5-33
1 – Cylinder Block
2 – Fuse Wire
3–Piston
• Assemble the cylinder head and gasket to the
cylinder block (Figure 5-33, (1)).
• Torque the head as previously described.
• Turn the crank in the direction of engine rotation
and press the fuse wire between the piston and
head.
• Remove the head and take out the compressed
fuse wire.
• Measure the thickness of the compressed fuse
wire at four positions and calculate the average
top clearance for each piston.
Figure 5-3 4
Figure 5-34
1 – Fuse Wire
Inspecting the Intake / Exhaust Rocker
Arms
Excessive wear of the rocker arm bearings and
rocker arms will affect the duration and timing of the
valve opening and closings. This will reduce engine
performance in direct proportion to the amount of
wear.
Figure 5-3 5
Figure 5-35
1 – Exhaust Rocker Arm
2 – Intake Rocker Arm
3 – Rocker Arm Support
4 – Rocker Arm Shaft Assembly
Piston Top Clearance
0.78-0.98 mm
(0.031-0.039 in.)
0005616
(1)
(2)
(3)
0005617
(1)
0005618
(3)
(4)
(2)
(1)
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