Motor mounts are used to absorb the vibration caused by the engine so that the vibration does not disturb the passengers or driver of the vehicle. The motor mounts wear over time because of the constant exposure to the vibration of the engine. When the motor mounts quit absorbing the vibration of the engine, then it is time for a motor mount replacement.
When performing a motor mount replacement, the technician disconnects the negative battery cable and lift the vehicle off the ground using either jacks or a vehicle lift. Then they remove the motor mount fasteners. The engine is lifted with an engine hoist in order to access the motor mount. The old motor mount is removed, the mount area cleaned, and the new motor mount is installed. Disconnect the negative battery cable. The technician then lowers the engine so that is aligns properly with the new motor mount. The new fasteners are installed and secured to the new motor mount. The vehicle is lowered and the negative battery cable is reconnected. Finally the technician test drives the vehicle to verify the success of the repair.
Most manufacturer factory warranties will cover a motor mount replacement, if the motor mount fails due to a manufacturer defect or workmanship. There are extended auto warranties available that will cover the cost of replacing a motor mount under their more comprehensive plans.