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Control by Truck Owner Under Abnormal Conditions. Ordi-
narily the above automatic control devices will minimize, or
eliminate, the danger of crankcase dilution.
However, there are abnormal conditions of service when
the truck owner must aid in the control of crankcase dilution.
Short runs in cold weather, such as city driving and
excessive idling, do not permit the thorough warming up of
the engine nor the efficient operation of automatic control
devices. It is recommended that the oil be changed more often
when the truck is subjected to this type of operation.
Poor mechanical condition of the engine, such as scored
cylinders, poor ring fit, "sloppy" or loose pistons, faulty valves,
and poor ignition will increase crankcase dilution. Keep your
truck
in
good mechanical condition.
Poor fuels which contain portions hard to ignite and slow
to burn will increase crankcase dilution. Use good fuel.
Water in Crankcase. Serious lubrication troubles may result
in cold weather due to an accumulation of water in the oil pan.
A slight amount of exhaust gases pass the pistons and rings,
even under the most favorable conditions, and cause the forma-
tion of water
in
the oil pan, in a greater or lesser degree, until
the engine becomes warm. When the engine becomes thor-
oughly warm, the crankcase will no longer act as a condenser
and all of these gases will pass out through the crankcase
ventilator system.
Short runs in cold weather, such as city driving, will aggra-
vate this condition.
Corrosion. Practically all present day engine fuel contains a
small amount of sulphur which, in the state in which it is
found, is harmless; but this sulphur on burning, forms certain
gases, a small portion of which is likely to leak past the pistons
and rings and reacting with water, when present
in
the crank-
case, form corrosive acids.
As long as the gases and the internal walls of the crank-
case are hot enough to keep water vapor from condensing, no
harm will result; but when an engine is run in low tempera-
tures, moisture will collect and unite with the gases formed by
combustion; thus, acid will be formed and is likely to cause
serious etching or pitting. This etching, pitting or corrosion,
when using fuel containing considerable sulphur, manifests
• 76 •
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