Yanmar 1GM User Manual page 15

8
to make alignment. Insert a new cotter pin through the nut
and hole, then tap the head lightly to seat it. Bend one arm
over the flat on the nut and the other against the top of the
stud or bolt (Figure 13). Cut the arms to a suitable length
to prevent them from snagging on clothing or skin. When
the cotter pin is bent and its arms cut to length, it should be
tight. If it can be wiggled, it is improperly installed.
Do not reuse cotter pins, as their ends may break and al-
low the cotter pin to fall out and the fastener to loosen.
Circlips
Circlips can be internal or external design. They are
used to retain items on shafts (external type) or within
tubes (internal type). In some applications, circlips of
varying thickness are used to control the end play of parts
assemblies. These are often called selective circlips. Re-
place circlips during installation, as removal weakens and
deforms them.
Two basic styles of circlips are available: machined and
stamped circlips. Machined circlips (Figure 14) can be in-
stalled in either direction (shaft or housing) because both
faces are machined, thus creating two sharp edges.
Stamped circlips (Figure 15) are manufactured with one
sharp edge and one rounded edge. When installing
stamped circlips in a thrust situation, the sharp edge must
face away from the part producing the thrust. When in-
stalling circlips, observe the following:
a. Remove and install circlips with circlip pliers. See
Circlip Pliers in this chapter.
b. Compress or expand circlips only enough to install
them.
c. After the circlip is installed, make sure it is com-
pletely seated in its groove.
LUBRICANTS
Periodic lubrication ensures long life for any type of
equipment. The type of lubricant used is as important as
the lubrication service itself, although in an emergency
the wrong type of lubricant is better than none at all. The
following paragraphs describe the types of lubricants
most often required. Be sure to follow the manufacturer's
recommendations for lubricant types.
Generally, all liquid lubricants are called oil. They may
be mineral-based (including petroleum bases), natu-
ral-based (vegetable and animal bases), synthetic-based
or emulsions (mixtures). Grease is an oil to which a thick-
ening base has been added so that the- end product is
semi-solid. Grease is often classified by the type of thick-
ener added; lithium soap is commonly used.
CHAPTER ONE
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Engine Oil
Oil for marine and automotive four-stroke engines is
classified by the American Petroleum Institute (API) and
the Society of Automotive Engineers (SAE) in several
categories. Oil containers display these classifications on
the top or label. API oil classification is indicated by let-
ters; oils for gasoline engines are identified by an "S" and
oils for diesel engines are identified by a "C".
Viscosity is an indication of the oil's thickness. The
SAE uses numbers to indicate viscosity; thin oils have low
numbers while thick oils have high numbers. A "W" after
the number indicates that the viscosity testing was done at
low temperature to simulate cold-weather operation. En-
gine oils fall into the 5W-30 and 20W-50 range.
Multi-grade oils (for example lOW-40) are less viscous
(thinner) at low temperatures and more viscous (thicker)
at high temperatures. This allows the oil to perform effi-
ciently across a wide range of engine operating condi-