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DESCRIPTION AND OPERATION
Crankcase Ventilation
Lubricant becomes a mist in many areas of the
engine as the result of the motion of the parts
(e.g., rocker arms, pistons, crankshaft, camshaft
and rocker shaft). The mist rides the drafts of air
and other gases that circulate in the open spaces
in the engine. To prevent pressure buildup, the
open spaces are ducted through a pipe that
opens to the atmosphere near the bottom of the
engine.
The crankcase ventilation (CCV) system
separates the oily mist from the gases by
centrifugal force. The oil returns to the oil pan.
The remainder escapes to the atmosphere.
22
Figure 22 — Crankcase Ventilation System Separator
A turbine in the CCV separator, driven by a small
stream of oil striking its fins, spins at high speed.
The mixture of gases and oily mist trapped in the
valve cover and the timing gear cover drains onto
the top of the center of the turbine and runs down
onto several discs rotating with the turbine.
Separation occurs as the mixture, flung outward
by the turbine, strikes the walls of the CCV. The
droplets of mist coalesce into a liquid and drain
back into the oil pan along with the oil that drives
the turbine. The gases are free to leave via an
open port.
The open port connects to a tube leading to the
bottom of the engine where road draft draws the
gases into the atmosphere. Optionally, the open
port may be connected to the turbocharger inlet
to close the system. This returns the unburned
fuel to the combustion process. In the closed
system, a pressure regulator stops the small
turbine when the system pressure falls below a
safe point.
1. Separator Inlet Hose and Connector
2. Separator Outlet Hose Connector
3. Turbine
4. Drive Shaft
5. Separator Discs
6. Pressure Regulator
7. Pressure Regulator Diaphragm
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