Hydraulic Motor Mounts

Since MB hydraulic motor mounts are supposed to be filled with some type of glycol based fluids...is it possible to hear the fluid slosh around by shaking the mount (while it is out of the car)?

The reason I ask is I have come across some solid type mounts that have no fluid or chamber in the middle..just solid rubber. I need to buy new motor mounts for my 16V and want to make sure that they are indeed the "hydraulic" type.