Patent ID: 7959714

Claim:
A method for servicing an internal combustion engine crankcase ventilation filter comprising providing a substantially planar low profile housing having a mating base and cover defining a coalescing filter chamber retaining a coalescer filter element when said base and said cover are mated to each other, said method comprising providing said coalescer filter element and at least a selected one of said cover and said base with respective complemental first and second detents, and disabling mating of said base and said cover to each other with said coalescer filter element retained in said coalescing filter chamber unless a coalescer filter element is selected having said first detent complementally interacting with said second detent, providing a flow path for crankcase gas from said engine comprising providing said housing with a flow path therethrough extending from an air-oil inlet then through said coalescer filter element then to an air outlet, providing said coalescer filter element with an upstream face receiving an air-oil mixture, and a downstream face along which separated oil coalesces and from which separated air is discharged, providing said first detent at one of said faces, providing said second detent extending proximate said one face and interfacing with said first detent in keyed relation, providing said second detent with a directional guide surface guiding and directing flow therealong and also turning the flow from a first flow direction to a second flow direction.