Lesson 4/Learning Event 2
It is very important to remember that neither type of crankcase ventilation system can remove liquids. Gasoline
and water in the crankcase cannot be removed unless they are changed from a liquid to a gas. For this reason,
the engine must get hot enough to change these liquids into a gas. Engines that are operated without proper
warm-up, or are used for short runs only, will soon have a crankcase full of sludge. If the thermostat in the
cooling system opens too soon or if it is stuck open, the engine will not get hot enough to vaporize the water
and gasoline. To keep the lubricating oil clean, the engine must get hot!
All military vehicles use the positive crankcase ventilation system. Since 1965, federal law requires that all new
automotive vehicles manufactured or sold in this country use this system. The positive crankcase ventilation
system is part of the emission control system for vehicles which reduces the pollution in the air we breathe.