Positive Crankcase Ventilation: Description and Operation

The crankcase emission controls prevent crankcase gases from being released into the atmosphere. Instead, the gases are routed to the intake manifold. Crankcase gases are removed from the crankcase by positive crankcase ventilation (PCV). Intake manifold vacuum draws the crankcase gases out of the crank housing into the intake air stream, where they get ignited in the combustion process.

Fig. 41 Positive Crankcase Ventilation:

The fumes are extracted by a vapor hose (PCV hose) connection between the crankcase housing (outlet located center back of engine) and the air intake runner. At the air intake runner connection there is an orifice installed to regulate the vacuum flow, Fig. 41.




COMPONENT:

ORIFICE
The orifice in the intake runner is calibrated to allow the correct amount of vapors to enter the intake air stream.