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Motor mounts support the engine and isolate engine vibrations from the vehicle’s frame. A bad motor mount can result in issues that can affect both the performance and safety of your vehicle.

5 Signs Of Bad Motor Mounts

Although a bad motor mount sound (usually a clunking or banging noise) is typically the first indication of failure, there are other signs you need to be mindful of as well.

Here are some of the most common broken motor mount symptoms:

Abnormal vibrations

The rubber or liquid-filled portion of the motor mount helps absorb vibrations from the engine. As such, when one or more motor mounts fail, vibrations from the engine may travel through the chassis and into the cabin of the vehicle.

Fluid mounts leak and collapse, and rubber mounts can deteriorate due to oil contamination, both of which cause the mount to lose its vibration insulating ability.

old and new motor mounts
The motor mount on the right is a problem mount from a 2004 E320 Mercedes that had a very pronounced vibration only when the vehicle was in reverse due to the collapsed mount. The mount on the left is a new mount held next to the old mount for comparison. Collapsed transmission mounts can cause similar issues. | Image source: Richard McCuistian
dirty motor mount
A lot of dirt can be packed into some types of mounts or a piece of road gravel can get wedged in the rubber on mounts like the one in the photo. This mount was removed for replacement due to an engine vibration under load. After the rock was removed, the vibration disappeared. | Image source: Richard McCuistian

Unusual noises

As mentioned, a failed motor mount may make a clunking or banging noise and/or you may feel the engine shift and you might hear the fan hitting the shroud on a rear-wheel drive vehicle with a broken mount.

If one or more mounts are broken rather than simply collapsed, the engine may raise up on one side or the other depending on whether the vehicle is in reverse or drive. Some engine mounts have a steel bracket integral with the mount to prevent the engine from raising too much if the mount’s rubber breaks.

Those broken mounts are usually easy to detect from under the vehicle or with the hood open while an assistant gently accelerates the engine with the brakes locked.

The sound is most noticeable upon abrupt acceleration or deceleration. You may also hear a noise when going over bumps but note that this is extremely rare.

Sometimes even on a vehicle with good mounts there will be vibration transmitted to the frame from the engine due to binding engine or transmission mounts. This tends to be more common on vehicles that have had the engine removed and replaced. Dealer specialists will sometimes loosen all the mounts and even the exhaust and let the engine shift to its desired position by working it through the gears with the brakes locked. Then they’ll shut the engine off and tighten the mounts very carefully to see if the vibration or “body boom,” as some call it, is gone.

Irregular engine position

Another sign of a bad motor mount is a misaligned engine. As you now know, one of the functions of the motor mount is to make sure the engine is securely situated and won’t serve as an obstruction to the other components.

Consequently, if one or two of your motor mounts get damaged, your engine may shift or sag.

You may not notice the shifting or sagging, so it’s best to take your vehicle to an experienced mechanic for a thorough inspection.

Damage to the engine

In some cases, if multiple motor mounts fail completely, they can cause damage to the engine. Without support from the mounts, the engine will be free to move around, leading to potential damage.

Damage to other components

A failed motor mount can put the engine at an extreme angle, and that can cause other components, such as wiring or belts and hoses, to stretch beyond their limits and break.

Can You Drive with Bad Motor Mounts?

You can, but not for long. At first, a bad motor mount may just make some unnerving noises. But the mount will continue to deteriorate over time, and that can lead to bigger problems that can make your vehicle unsafe.

Replacing a bad motor mount as soon as possible is a smart choice. The action is likely to save you from more costly repairs in the long run, while also helping to keep your vehicle safe.

close up shot of a motor mount attached to an engine
You can drive with bad motor mounts but not for long. Motor mounts will continue to deteriorate over time, making your vehicle unsafe.

Should I Replace All Motor Mounts?

Typically, there are three to four mounts holding the engine and transmission in place. But in most cases, you don’t need to replace them all at once. In the event that one of the mounts gets worn out or busted, you can usually just change out the one that needs replacement.

In some cases, however, you may want to replace all the mounts at once as a preventative measure. Often, when one mount fails, it will put additional strain on the other mounts, leading to their early demise.

Even though motor mounts are designed to last the life of the vehicle, that doesn’t always happen. On average, replacing a motor mount can cost you around $220 to well over $1,000 if you have a professional do the job for you. The cost of mounts themselves depends on the quantity, brand, and fitment.

Some motor mounts are easy to replace; others are extremely difficult. Know your limitations.

Once you know what to look for, broken motor mount symptoms become quite easy to spot. While it is still best to leave the diagnosis to an experienced auto mechanic, it still pays to educate yourself so you’ll be able to answer questions such as, “what does a bad motor mount feel like,” and know how to respond.

Usually, motor mounts just deteriorate after years of use and exposure to the elements. Though in some cases, other issues can cause the mounts to fail prematurely. For example, an engine oil leak might trickle down onto the motor mount, causing the rubber portion to fail.

Whatever the reason, be sure to give your motor mounts proper attention so you can enjoy a safe and smooth drive.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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