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Section 4 Engine Service
Checking Oil Level and Condition
Crankcase oil in four-cycle engines should be
checked periodically. Preferably, it should be checked
each time fuel is added. The engine manufacturer
provides a means of visually inspecting the level and
condition of the oil. Use the type and viscosity grade
of oil recommended by the manufacturer and main-
tain it at the proper operating level.
To check the oil level in engines equipped with
a dipstick, withdraw the dipstick and wipe it dry.
Reinsert the dipstick as far as it will go. Withdraw
it a second time and observe the oil level on the
dipstick. See Figure 13-2.
The markings on dipsticks may vary, but all will
have a Low (Add) mark and a Full mark. Add oil if the
level is at or below the Low mark. Do not run the engine
with oil showing above the Full mark on the dipstick. If
the crankcase oil level is high, drain some oil.
Overfi lling the crankcase with oil can foul plugs and
cause the engine to use too much oil.
Some small gasoline engines do not have dip-
sticks. Instead, they have a fi ller plug that threads
into the fi ller hole to seal out dirt and seal in the oil.
Figure 13-3 shows the proper method of loosening
one type of fi ller plug. When the plug is removed,
the oil level should be at the top of the fi ller hole or
to a mark just inside the fi ller hole.
Caution
Overfilling O Ov v e fi in g t h h e e crankcase r r e wi th oil c an foul plugs and
cause ca a a us e t h e eng e gi ne e e t o o us e e to o much oil.
If the engine oil level drops at an excessive rate
(requires the addition of oil frequently), look for
the cause. Refer to a troubleshooting chart for the
particular engine at hand. Troubleshooting charts
are covered later in this chapter. Typical causes of
excess oil consumption are external leaks, worn oil
seals around the crankshaft, worn valve guides,
worn piston rings, or a hot running engine.
The color of used oil is not always an accurate indi-
cation of its condition. Additives in the oil may change
its color without decreasing its lubricating qualities.
Figure 13-1.
This chain saw engine is being cleaned with
compressed air.
Figure 13-2.
Checking the oil is an important part of preventive
maintenance.
Figure 13-3.
A screwdriver can be used to remove the type of oil
fi ller plug shown here.
Plug