A one-piece, molded plastic end cap (1) is designed for installation in a diesel engine fuel filter. The end cap (1) comprises a disk-shaped filter support component (2), with a top portion adhesively connected to the fuel filter center tube (8) and filter media (9), and a bottom portion which includes a downward-facing, slotted, cylindrical nipple (3). The distal end of the nipple (3) protrudes slightly from the bottom of the fuel filter housing (7), and is threaded to accept a drain plug/self-venting valve (10). The self-venting valve (10) is designed such that, the internal fuel filter vacuum is broken through a capillary-type action, and air subsequently enters the filter, and contaminants (primarily water) are able to drain freely.