968 Cabriolet L4-2990cc 3.0L DOHC (1993)
Positive Crankcase Ventilation: Description and Operation
PURPOSE
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.
OPERATION
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.