Transmission mounts secure the transmission to your vehicle’s frame and absorb road shocks. Most cars have several transmission mounts. If one of them breaks, you probably will feel engine vibrations or shaking. You also may hear clunking or knocking sounds when idling or while driving. These noises can be the result of damaged rubber blocks which, in turn, can damage the transmission. In addition, transmission fluids leaking onto the transmission mount may make the problem worse. Another symptom of damaged transmission mounts is that your engine may start sagging to one side. This misalignment is another source of unwanted sounds while accelerating. If any of these symptoms persist, have your transmission checked by a car care specialist.