Diesel Engines

Although the function of the crankcase ventilation system is the same for both gasoline and diesel engines, the systems and control valves are different. Diesel engines use either a Closed Crankcase Ventilation system or Crankcase Depression Regulator to regulate flow of blow-by gases back into the engine.

Fig. 33 Closed Crankcase Ventilation (CCV) system. 4-110/1.8L diesel engines:

Closed Crankcase Ventilation

This system, used on L-4 diesel engines, consists of a baffle plate oil separator inside the cam cover, PCV valve on the cover, and a hose connecting the valve and intake manifold, Fig. 33. The baffle plate separates oil particles from blow-by gases and provides an area in the cam cover for gases to collect. When pressure in the cam cover exceeds intake manifold pressure by a specified amount, the PCV valve opens and blow-by gases are forced into the intake manifold and drawn into the engine.