The anelastic spectra of La1−xCaxMnO3 with x=0.40 have been measured in a wide temperature range. The ferromagnetic–paramagnetic and the structural orthorhombic–trigonal phase transitions are clearly identified and the nature of an elastic energy loss peak just below TC is discussed. Its temperature and frequency dependences are typical of the dynamic susceptibilities of phase inhomogeneous or frustrated compounds like relaxor ferroelectric perovskites or spin glasses. Then at low temperature these systems seem to be characterized by a phase separation scenario presenting a glass-like dynamics. The bases of a forthcoming quantitative study have been identified.