The purpose of engine motor transmission mounts: Most mounts made of metal and rubber, many newer model mounts are filled with hydraulic fluid, some advance hydraulic mounts come with electronic variable speed control by ECM engine control module. The basic design are the same to support between engine, transmission and subframe. They work hard to keep engine and transmission running smooth minimizing the amount of rattling and vibration from acceleration and stops. At the same time mounts are supporting all major power train systems keeping all mechanical components in balance level and position. Motor mounts are extremely important vehicle parts that stabilize and align a vehicle engine inside the engine compartment. Although small in size and relatively cheap in cost, motor mounts can cause tremendous mechanical problems if they break or go bad. Engine motor mounts are small parts that are used to stabilize and properly align a vehicle engine. When motor mounts go bad, they can cause a variety of symptoms, ranging from mechanical damage to excessive engine noise.