Yanmar 6LY3 series Service Manual

ENGINE
Inspecting the Cylinder Block and Components
5-28 6LY3 Service Manual
© 2007 Yanmar Marine International
Inspecting the Cylinder Head
The cylinder head is subjected to very severe
operating conditions with drastic and repeated
fluctuations of high pressure and high temperature.
Thoroughly remove all the carbon and dirt after
disassembling. Clean the cylinder head surface
and carefully inspect all of the parts.
Inspect the cylinder head for the following
conditions:
1. Check for distortion of the cylinder head mating
surfaces.
• Clean the cylinder head surface.
• Place a straight-edge along each of the four
sides and each diagonal.
• Measure the clearance between the
straight-edge and mating surface with a feeler
gauge.
Figure 5-15
Figure 5-15
2. Check for cracks in the cylinder combustion
surfaces.
• Remove the fuel injection nozzle, intake and
exhaust valve.
• Check for discoloration or distortion.
• Perform a dye penetrent inspection to check for
any cracks.
Figure 5-16
Figure 5-16
3. Check the intake and exhaust valve seats.
Check the surface and width of the valve seats
(Figure 5-17). If the seat width is too wide, or if
the surface is rough, correct to the following
standards:
Figure 5-17
Figure 5-17
Cylinder Head Distortion
Standard Wear Limit
0.05 mm
(0.002 in.) or less
0.20 mm
(0.008 in.)
0005597
Seat Angle
Intake 90°
Exhaust 90°
Intake Seat Width
Standard Limit
1.07-1.24 mm
(0.042-0.049 in.)
1.74 mm
(0.069 in.)
Exhaust Seat Width
Standard Limit
1.24-1.45 mm
(0.049-0.057 in.)
1.94 mm
(0.076 in.)
0005598
0005599

Yanmar 6LY3 series Specifications

General

Brand	Yanmar
Model	6LY3 series
Category	Engine
Language	English