The present invention concerns a jet pump with a sucking jet pump (22) comprising a flow duct (45) of decreasing cross-section and a suction tube insert (26) of a by-pass arrangement (23), which insert (26) is inserted in the flow duct (45). The sucking jet pump (22) further comprises a valve arrangement (12). The flow duct (45), suction pump insert (26) and valve arrangement (12) form a structural unit. The sucking jet pump (22) comprises a nozzle insert (25) which is inserted in a duct (24) and forms the flow duct (45) of decreasing cross-section.
