We have performed the time-dependent spectroscopy of the B P-3(1) State of the HgAr van der Waals complex using a two-color picosecond pump-probe experiment. Recurrences can be observed for a short delay between pump and probe pulses and the oscillations disappear after 100 ps as a result of the large anisotropy of the weak B van der Waals well. The time-resolved approach is well adapted to the observation of vibrational levels close to the dissociation limit. Moreover, the spectral bandwidth of the picosecond laser allows for a selective excitation of groups of levels in various parts of the potential well.