Diesel Models

The PCV system uses a control valve that mixes air from air cleaner with crankcase vapors from valve cover. These vapors are directed into intake manifold for burning. The control valve reduces flow rate when throttle is closed so engine will not draw in excess amounts of air.

Fig 1: Datsun Crankcase Ventilation System (Gasoline Pickup Models)

Courtesy of NISSAN NORTH AMERICA, INC.

Note direction of flow. 

Fig 2: Datsun Crankcase Ventilation System (Sentra & 310 Models)

Courtesy of NISSAN NORTH AMERICA, INC.

Note direction of flow.