Your car’s engine supplies the rotational power necessary to move your vehicle along. When you think about how much effort it takes to get a couple thousand pounds of metal moving, most people only consider the engine parts that move. However, without an equally strong method to hold an engine in place, that energy is unable to transmit to the wheels. It is up to the motor mounts to hold your engine firmly in place, though gently enough to allow minor movement. Typically, these parts last for years, but they do wear out eventually. So, what are the symptoms of a bad motor mount?
Bad Motor Mount Symptoms
There are a few bad motor mount symptoms you need to know. While catastrophic motor mount failure is rare, the longer your drive with a worn-out motor mount, the greater the chance of causing damage to other components. Thus, pay close attention if you notice any of the following bad motor mount signs:
At the top of the list of symptoms of a bad motor mount is too much engine movement. This one is easy to test. First, chock the wheels and set the parking brake to prevent the vehicle from moving forward or backward. Next, open the hood of the vehicle, then get in the driver’s seat. Start the engine and position yourself so that you can see the engine through the gap between the back of the hood and the bottom of the windshield. If this isn’t possible, ask a helper to stand on either side (not in front) of the engine bay and observe for you. Put your foot firmly on the brake and shift the transmission into drive and apply a small amount of throttle. Observe how much the engine moves. With your foot still firmly on the brake, shift the transmission into reverse and apply a small amount of throttle. Again, observe how much the engine moves. A slight rocking of roughly an inch forward or backward is usually acceptable. But if the engine rises or moves more than an inch, you probably need new motor mounts.
Vibration or Shaking
Another one of the more common bad motor mount symptoms is excessive vibration or shaking. Ideally, an engine should operate smoothly, but this isn’t always the case. Some engines have inherent vibrations due to their design. Others may have a maintenance issue that leads to misfiring. Considering the Rube Goldberg-esque arrangement of parts inside an engine, it is bound to have some external movement. That movement is usually kept at bay by the motor mounts. But if those motors mounts are worn out and can’t keep the motion at bay, the engine will shake and vibrate even when just sitting still in park or neutral.
You should find it nearly noticeable when putting your vehicle in drive or reverse from park. The engine RPM may drop slightly, but that’s about it. Any sudden jerking or slamming means that the engine is not getting held in place correctly. If the load on the engine changes quickly, it can cause the engine to slam against the loose mounts. Gears changes, especially under load or while slowing down, may feel jarring.
A leaking hose is also a possible sign of a bad motor mount. Hoses and lines under the hood are designed by engineers to move around. Hangers and brackets hold the hoses and lines out of harm’s way, but there is a movement limit. A worn-out motor mount will allow the engine to move farther than expected taking those hoses right along with it. This can result in a hose getting torn from its connector in extreme cases. More often, a hose will begin to rub against another component. Eventually, the friction causes a hole in the flexible hose. Look for damp hoses, especially where clearances between components are tight, and check hose ends at the connections for leaks or tearing from getting pulled by the excessive engine movement.
Electrical gremlins are another possible sign of a bad motor mount. The same way worn-out motor mounts can damage hoses, they can also damage wiring. Excessive motor movement can pull at wiring harness connections or possibly even break them. Wiring can also get pinched between the engine and surrounding engine compartment. In extreme cases, driving for prolonged periods can even cause breakages within the wiring that are difficult to see, causing open circuits. This kind of damage is usually only found in extreme cases of delayed maintenance.
Fixing a Bad Motor Mount
Now that you know the symptoms of bad motor mount components, you can decide how to handle the problem. Changing out a bad motor mount usually requires lifting equipment like a floor jack and jack stands. You will need to support the motor while the old motor mount is removed and a new one slides into place. The exception is an upper engine mount known as a torque strut. This mount is usually attached near the top of the engine and connects to a strut tower. For most vehicles, you can replace it with just a little wiggling to get it back in place. Of course, the design of your vehicle makes a big difference in the difficulty of this repair job. Something like a transmission mount is possibly buried behind the suspension or you could find it sitting out in the open underneath the transmission tunnel.
Your local NAPA Auto Care center can easily handle swapping out a bad motor mount and get you back on the road. Or you can visit your local NAPA Auto Parts store and get everything you need to DIY in your own garage. Whichever path you choose, know that NAPA is here to keep you and your vehicle rolling.
Check out all the motor mounts and related parts available on NAPAonline or trust one of our 17,000 NAPA Auto Care locations for routine maintenance and repairs. For more information on signs of motor mounts going bad, chat with a knowledgeable expert at your local NAPA Auto Parts store. Make sure to check out NAPA Rewards and start getting 1 Point for every $1 you spend on online and at participating NAPA Auto Parts stores. You get $5 off your next purchase for every 100 Points you earn!
Photo courtesy of Wikimedia Commons.
With an automotive writing career spanning over two decades, Brian has a passion for sharing the automotive lifestyle. An avid DIYer he can usually be found working on one of his many project cars. His current collection includes a 1969 Olds Delta 88 convertible, BMW E46 sedan, and a slant-6 powered 1975 Plymouth Duster.