I claim the ornamental design for a skull-shaped positive crankcase ventilation valve, as shown and described.
The patent or application file contains at least one drawing/photograph executed in color. Copies of this patent or patent application publication with color drawing(s)/photograph(s) will be provided by the Office upon request and payment of the necessary fee.
FIG. 1 is a perspective top photographic image of a skull-shaped positive crankcase ventilation valve;
FIG. 2 is a perspective bottom photographic image thereof;
FIG. 3 is a front photographic image thereof;
FIG. 4 is a right side photographic image thereof;
FIG. 5 is a rear photographic image thereof;
FIG. 6 is a left side photographic image thereof;
FIG. 7 is a top photographic image thereof; and,
FIG. 8 is a bottom photographic image thereof.
Color photographs are presented to properly present ornamental effects.