An engine mount is the part that holds the engine in your car. In most cars, an engine and transmission are bolted together and held in place by three or four mounts. The mount that holds the transmission is called the transmission mount, others are referred to as engine mounts.
One part of the engine mount is bolted to the car body or frame. Another part holds the engine. An engine is a source of vibration, as it has many moving and rotating parts. The job of an engine mount is not only to hold the engine in place, but to reduce the engine vibration felt inside the car.
Engine mounts are made with a rubber material so that there is no direct metal-to-metal contact between the engine and the car body. To further dampen the vibration, some engine mounts are filled with liquid. A liquid-filled engine mount works like a shock absorber.
Some car manufacturers (e.g. Toyota, Honda) use active vacuum-controlled engine mounts that vary dampening as needed. Porsche offers electromagnetic mounts to actively reduce engine vibration transferred to the body.
An engine mount doesn't need any maintenance or regular servicing. It only needs to be replaced when it fails or wears out.
How long can an engine mount last? In some cars, engine mounts can last the life of the vehicle. We see the most of the problems with engine mounts starting to show in 5-7 year-old vehicles. Transmission mounts last longer.