Engine mount: how it works, symptoms, problems
Top engine mount in Hyundai Elantra
An engine mount is the part that holds the engine in your car. In a typical car, the 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 an 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.
Transmission mount, Toyota Camry. Click for larger photo
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.
Engine mount problems
The most common problem with the engine mount is when the rubber part breaks or separates or when liquid starts leaking out of the liquid-filled mount.
Common symptoms of a failed engine mount is the increase in engine noise and vibration felt inside the car.
Often, the excessive vibration is more noticeable at idle with the transmission engaged. For example, in some 07-08 Honda Civic models, a failing passenger side mount can cause a vibration and growling noise
New vs broken engine mount.
felt in Reverse when the engine is started cold.
In Mazda 3, a broken top engine mount can cause vibration at idle, especially noticeable when the transmission is in Drive.
In some cars, a broken engine mount can also cause a noticeable jolt or thump when
Leaking engine mount
shifting into Drive or Reverse or when accelerating or decelerating.
In Honda Accord V6, Odyssey and Pilot, for example, a failed front engine mount can cause harsh transmission engagement when shifting between Park, Drive; and Reverse, as well as vibration at highway speeds. The solution is to replace the front hydraulic engine mount.
In some Mitsubishi cars, a failed engine mount can cause vibration felt in the steering at idle when the transmission is in Drive. The vibration disappears when shifted to Neutral.
A bad transmission mount may also cause squeaking when shifting gears.
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