The ornamental design for a mobile cementpump with washout feature, as shown and described.
FIG. 1 is a perspective view of a mobile cement pump with washout feature showing my new design;
FIG. 2 is a right side view of thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a front view thereof; and,
FIG. 6 is a top view thereof.
The broken line showing of surface features and internal components is included for the purpose of illustrating portions of the mobile cement pump with washout feature and forms no part of the claimed design.