A hydraulic engine mount includes an orifice track formed in a partition between an elastomer body and a base member of the mount, the partition being formed by two separable orifice plates. An annular fluid filled tuning chamber is disposed adjacent the orifice track and separated therefrom by a flexible membrane. An actuator is in communication with the tuning chamber for forcing pressure fluid into or out of the chamber to selectively deflect or distend the membrane to modify the cross sectional area of the orifice track and the vibration damping characteristics of the mount.