Sentra L4-1681cc DSL SOHC (CD17) (1983)
Positive Crankcase Ventilation: Description and Operation
Fig. 1 Closed crankcase emission control system.
DIESEL ENGINES
This system, Fig. 1, prevents blow-by gasses from entering the atmosphere and keeps the internal crankcase pressure constant. During engine
operation, the blow-by gasses are fed into the intake manifold by the crankcase emission control valve which is activated by pressure within the rocker
cover. When intake air flow is restricted by the throttle chamber, the internal rocker cover pressure decreases. When this occurs, the crankcase emission
control valve keeps the internal rocker pressure constant so that air or dust is not drawn around the crankshaft oil seal.