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Crankcase Ventilation System Description - LE5 or LE9

General Description

A crankcase ventilation system is used to consume crankcase vapours in the combustion process instead of venting them to atmosphere. Fresh air from the inlet system is supplied to the crankcase, mixed with blow-by gases and then passed through a calibrated orifice into the inlet manifold.

Operation


1914690

The primary control is through the positive crankcase ventilation (PCV) orifice which meters the flow at a rate depending on inlet vacuum. The PCV orifice is an integral part of the camshaft cover. If abnormal operating conditions occur, the system is designed to allow excessive amounts of blow by gases to back flow through the crankcase vent into the intake system to be consumed by normal combustion.

Results of Incorrect Operation

A plugged orifice may cause the following conditions:

    •  Rough idle
    •  Stalling or slow idle speed
    •  Oil leaks
    •  Sludge in engine

A leaking orifice may cause the following conditions:

    •  Rough idle
    •  Stalling
    •  High idle speed
   


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