Extensive solar data obtained over the period May to August 1982 are analyzed to show the continued existence, over a six-year period, of a 13-day velocity signal of 6 m/s amplitude. Mean daily velocity signals are shown with a superimposed best-fit sine wave, and the power spectrum obtained from that fit is presented. Data comparing measured and calculated relative phases for the 13.035 day period are given. The constancy of the signal's amplitude and its long coherence time may be partly explained by velocity signals induced by active region rotation, but some fundamental cause, possibly related to the rapid rotation of the solar core, is strongly suggested.