What Are the Symptoms of a Bad Motor Mount?

The most common symptoms of a bad motor mount are excessive vibration, clunking or thumping noises during acceleration or shifting, and noticeable engine movement under the hood. Drivers may also feel the car lurch, shudder, or shake more than usual, particularly when starting from a stop or changing gears. These signs usually worsen over time and can lead to further damage if the mount is not replaced.

How Motor Mounts Work—and Why Failure Matters

Motor mounts (also called engine mounts) are the components that secure the engine—and often the transmission—to the vehicle’s chassis. Typically made of metal with rubber or hydraulic (fluid-filled) cores, they serve two essential functions: holding the engine firmly in place and isolating engine vibration so it doesn’t transfer harshly into the cabin. When a mount wears out, breaks, or leaks, it can no longer absorb these forces effectively, leading to a suite of symptoms that drivers can feel, hear, and sometimes even see.

Key Symptoms of a Bad Motor Mount

1. Excessive Vibration Inside the Cabin

One of the earliest and most noticeable signs of a failing motor mount is an increase in vibration felt through the steering wheel, seat, floor, or dashboard. This happens because the rubber or hydraulic material inside the mount deteriorates, hardens, tears, or leaks, allowing more engine vibration to transfer into the vehicle’s structure.

The main patterns of vibration linked to bad motor mounts can be grouped and understood more systematically.

• Strong vibration at idle: The car shakes noticeably when stopped at a light or in park, but may smooth out slightly as you speed up.
• Vibration that improves when in neutral: Shaking is worst when in drive with the brake applied, and less severe when shifted into neutral or park.
• Vibration that changes with gear selection: Some mounts load differently in reverse vs. drive, so vibrations might be stronger backing up than moving forward.
• Localized buzzing or rattling in the dash or console: Weak mounts can cause panels, trim, or accessories to resonate, creating secondary rattles.

These vibration patterns often start subtly and become more pronounced as the mount continues to degrade, making them a useful early warning sign before catastrophic failure.

2. Clunking, Banging, or Thumping Noises

When a motor mount fails severely, the engine can shift more dramatically within the engine bay. This movement can create sharp, metallic, or dull thumping noises as components hit each other or as the engine rocks against the remaining mounts or subframe.

These noises typically follow recognizable situations and can be grouped to help drivers and technicians identify a failing mount.

• Clunk when shifting from park to drive or reverse: A noticeable “kick” or “thud” when engaging a gear, especially if felt from the front of the car.
• Bang or thump during hard acceleration: The engine rocks backward, striking or stressing other mounts or brackets under load.
• Noise when lifting off the throttle: Letting off the gas abruptly can cause the engine to rock forward, producing a counter “clunk.”
• Repeated knocking over bumps: On very worn mounts, the engine may move enough for components to tap or knock when the suspension travels.

Over time, these sounds usually grow louder and more frequent, indicating that the mount may be close to complete failure and should be inspected promptly.

3. Noticeable Engine Movement Under the Hood

Another hallmark symptom of a bad motor mount is visible engine movement when the vehicle is started, revved, or shifted between gears. Modern engines should move only slightly; large or abrupt rocking motions suggest that one or more mounts are no longer holding the powertrain securely.

There are several observable engine behaviors that point strongly toward mount problems.

• Engine lifting or twisting when revved in park: With the hood safely open, the engine may rise noticeably on one side as the throttle is blipped.
• Heavy rocking when shifting between drive and reverse: The whole powertrain appears to lurch back and forth more than expected.
• Engine out of alignment: In severe cases, the engine may appear tilted, shifted to one side, or sitting lower than normal.
• Visible gap, crack, or separation in a mount: On visual inspection, the rubber section may be torn or the mount may appear broken or split.

These visual cues, especially when paired with noise and vibration, are strong indicators that a motor mount has failed and needs professional evaluation.

4. Harshness During Acceleration, Braking, or Shifting

Because mounts help control how the engine and transmission move under load, failure can be felt as increased harshness during normal driving. Instead of smooth engagement, the vehicle may react more abruptly when you press or release the gas pedal, or when the transmission changes gears.

Drivers frequently report a consistent set of drivability changes once mounts are compromised.

• Jerky or lurching starts from a stop: As power is applied, the engine rocks rather than delivering power smoothly to the wheels.
• “Kick” or “slam” between gear changes: Particularly in automatic transmissions, shifts can feel more violent as the powertrain moves.
• Shuddering during acceleration: A pronounced shake or wobble may occur when accelerating up a hill or merging onto a highway.
• More abrupt engine braking feel: Letting off the throttle may cause a sudden deceleration jolt as the engine shifts position.

These symptoms can sometimes be mistaken for transmission or drivetrain issues, which is why a proper inspection of the mounts is important before assuming a more expensive failure.

5. Unusual Engine or Exhaust Misalignment and Contact

When motor mounts sag or collapse, they can change the alignment of the engine, exhaust, and surrounding components. That misalignment not only creates noise but can also lead to premature wear or damage of connected parts.

Several secondary issues can appear as a result of the engine no longer sitting in its intended position.

• Exhaust rattles or scraping: A tilted engine can pull or push exhaust pipes against heat shields, crossmembers, or the body, causing rattling sounds.
• Stretched or kinked hoses and wiring: Excess engine movement may strain coolant hoses, vacuum lines, or electrical connectors.
• Contact marks in the engine bay: Shiny or worn spots where the engine or accessories have been rubbing against nearby parts.
• Inconsistent shifter feel in some vehicles: On cars where the shifter links directly to the transmission, excess movement can affect shift precision.

These alignment-related signs often show up after the more basic vibration and noise symptoms and can indicate that the failing mount has been neglected for some time.

6. Hydraulic (Fluid-Filled) Mount Leaks

Many modern vehicles, particularly luxury models and some SUVs, use hydraulic or “active” motor mounts that contain fluid to better absorb vibration. When these mounts fail, they may leak, providing a clear visual clue in addition to the usual noise and vibration.

Fluid-filled mount problems tend to reveal themselves in several specific ways.

• Oily or wet residue on or near the mount: The mount housing may appear damp, with fluid collecting on its surface or nearby brackets.
• Dark spots under the engine area: Puddles or stains on the ground that are not engine oil, coolant, or transmission fluid.
• Rapid increase in vibration: Once the internal fluid escapes, the mount’s ability to absorb vibration drops quickly.
• Visible collapse of the mount: The engine may sit lower on the side of the failed hydraulic mount compared with the others.

Because hydraulic mounts are more complex and more expensive, catching leaks early can help avoid collateral damage and unexpected drivability issues.

How to Differentiate Motor Mount Problems From Other Issues

Many symptoms of bad motor mounts—such as vibration, noise, and rough shifting—overlap with other mechanical problems. Correct diagnosis is essential to avoid replacing the wrong parts and to ensure safety.

Drivers and technicians often rely on a combination of checks and comparisons to narrow down the cause of the symptoms.

• Compare vibration with engine speed vs. vehicle speed: If vibration changes with engine RPM (even when stationary), mounts or engine balance are likely; if it changes mainly with road speed, tires or suspension are more suspect.
• Inspect tires, wheels, and suspension first: Rule out unbalanced wheels, bent rims, or worn suspension bushings that can also cause shaking.
• Check for misfires or rough running: Engine misfires can mimic mount-related vibrations; a scan tool and basic tune-up checks can distinguish the two.
• Use power braking tests (by a professional): Mechanics may hold the brake and apply throttle in drive or reverse to observe excessive engine movement.
• Perform a visual mount inspection: Look for torn rubber, separated metal brackets, missing bolts, or obvious leaning of the engine.

By systematically comparing these clues, it becomes easier to tell whether mounts are the root cause, a contributing factor, or simply one of several issues affecting the vehicle.

Risks of Driving With a Bad Motor Mount

While it is sometimes possible to drive for a period with a worn motor mount, doing so carries increasing risks to both the vehicle and the occupants’ comfort. In extreme cases, a completely broken mount can compromise drivability and safety.

The potential consequences of ignoring motor mount problems cover both immediate and long-term concerns.

• Increased wear on other mounts: A single failed mount forces the remaining mounts to absorb extra stress, leading to a chain-reaction of failures.
• Damage to exhaust, hoses, and wiring: Excess movement can crack exhaust manifolds, tear hoses, or pull on wiring harnesses.
• Transmission and drivetrain stress: Misalignment between engine and transmission can accelerate wear on axles, CV joints, or driveshaft components.
• Reduced comfort and perceived refinement: Excess vibration makes the vehicle feel older and less refined, particularly at idle or in traffic.
• Safety concerns in severe failures: In rare extreme cases, a broken mount can allow the engine to shift enough to interfere with throttle linkage, steering components, or even cause metal-to-metal contact in a crash.

Because the cost of replacing a mount is typically far lower than repairing secondary damage, timely attention to symptoms usually saves money and helps maintain overall vehicle health.

When to See a Mechanic—and What to Expect

If you notice increasing vibration, clunking noises, or visible engine movement, it is wise to have a professional mechanic inspect the motor mounts. A proper evaluation involves lifting the vehicle, visually examining each mount, and sometimes gently prying or loading the engine to check for excessive play.

For drivers considering next steps, it helps to know the typical process and outcomes of a motor mount inspection and repair.

• Initial symptom review: You describe when the vibrations or noises occur—idle, acceleration, shifting—and whether they are getting worse.
• Physical inspection: The shop checks each mount for cracks, separation, leaks, or broken hardware, and looks for signs of engine misalignment.
• Dynamic tests: The engine may be revved in gear with the brakes applied (in a controlled setting) to observe excessive movement.
• Mount replacement plan: If one mount is clearly bad, the mechanic may recommend replacing it—and sometimes nearby mounts—depending on age and design.
• Post-repair evaluation: After replacement, a test drive confirms that vibration and noise levels have returned to normal.

Armed with a clear understanding of symptoms and the diagnostic process, vehicle owners can better discuss options, prioritize repairs, and avoid misdiagnosis of more expensive components.

Summary

Bad motor mounts typically reveal themselves through a combination of excessive vibration, clunking or thumping noises, and visible engine movement—especially during idle, acceleration, or gear changes. As the mounts lose their ability to secure and isolate the engine, drivers may experience harsh starts, rough shifting, exhaust rattles, and even fluid leaks from hydraulic mounts. While some symptoms overlap with other mechanical issues, careful observation and professional inspection can confirm the diagnosis. Addressing failing motor mounts promptly not only restores comfort and refinement but also prevents collateral damage to the exhaust system, drivetrain, and other critical components.

Will bad motor mounts throw a code?

Yes, bad engine mounts can throw a code, especially in modern vehicles with electronic or hydraulic mounts that communicate with the car’s computer. They can also cause a code indirectly if excessive engine vibration triggers other sensors, such as a knock sensor. 
This video explains how engine mounts can trigger a code: 58sMotorCarNutYouTube · Apr 17, 2025
Direct causes

• Electronic/hydraulic mounts: Many modern cars use mounts that have a sensor and are controlled by the car’s computer to adjust stiffness for different driving conditions. A failure in this system will trigger a code. 
• Specific designs: Some vehicles, like certain Volvos, have vacuum-controlled mounts that can cause a check engine light if they fail. 

Indirect causes

• Vibration triggering other sensors: If a mount fails, the engine can vibrate excessively against the subframe. This vibration can be so severe that it falsely triggers other sensors, most commonly a knock sensor, leading to a code. 
• Damage to nearby components: Extreme movement from a failed mount could cause stress on nearby wiring or sensors, leading to a malfunction and a code. 

This video explains how a bad engine mount can cause a knock sensor code: 49sNiX FiXYouTube · Oct 6, 2023
What to do

• Don’t ignore the code: If you get a code related to your engine mounts, it’s a real issue that needs to be addressed. 
• Scan for codes: Have the codes scanned to determine the exact issue. The scan tool will provide specific codes related to the mounts or other sensors. 
• Inspect the mounts: Check the mounts for physical signs of damage like cracking, leaks (for hydraulic mounts), or separation. 
• Consult a mechanic: A professional can properly diagnose the problem and replace the mounts or address any other related issues. 

Can an engine mount cause shaking?

Yes, a failing engine mount can cause shaking, vibration, and excessive noise. While engine mounts are designed to dampen engine vibrations, when they break or wear out, they can no longer effectively isolate the engine’s movement, allowing the vibrations to be transferred to the car’s body. 
You can watch this video to see a visual comparison of a good vs bad engine mount and the effect it has on the engine: 1mAuto Repair GuysYouTube · Sep 22, 2020
Symptoms of a bad engine mount

• Increased vibration: You will notice more vibration, especially at idle or during acceleration, and it may be felt in the steering wheel or through the car’s floor. 
• Rough idle: The engine may shake noticeably when the car is stopped in gear. 
• Clunking or banging noises: You may hear these sounds, particularly when shifting gears or accelerating from a stop, as the engine shifts and hits other parts. 
• Engine lurching: The engine may appear to move, lurch, or shift excessively during acceleration, braking, or gear changes. 
• Visible engine movement: When the engine is running, you may be able to see it moving or shifting more than it should. 

Why this happens

• Engine mounts are made of metal and rubber (or a liquid-filled hydraulic system). 
• Over time, the rubber can crack, deteriorate, or separate from the metal components. 
• When the mounts fail, they lose their ability to absorb and isolate the engine’s normal vibrations. 

This video explains the function of engine mounts and the consequences of a failing one: 1mFixITYouTube · Feb 5, 2025
What to do

• Have them inspected: If you suspect a bad engine mount, it’s best to have it inspected by a mechanic. 
• Replace them: A mechanic can replace the mounts to restore a smooth ride and prevent further damage to your vehicle. 
• Avoid sudden movements: While waiting for an inspection, avoid sudden accelerations or hard stops, as these can put extra stress on worn mounts. 

Can a bad motor mount affect transmission?

Yes, a bad motor mount can absolutely affect the transmission by causing vibrations, noise, shifting problems, and even potential long-term damage. Worn mounts allow the engine to move excessively, which can stress and misalign the transmission, leading to issues like jerky shifts, fluid leaks, and other damage over time. 
How bad motor mounts affect the transmission

• Excessive movement: When motor mounts fail, the engine and transmission are no longer properly secured. This can cause the entire assembly to shift and move excessively, especially during acceleration or gear changes. 
• Abnormal noise: The excessive movement can cause clunking or banging sounds, particularly when you shift gears or accelerate. 
• Shifting problems: The extra movement can put stress on internal transmission components, leading to a less smooth shifting experience. You may notice a jerky feel, resistance when shifting, or even a rougher ride. 
• Fluid leaks: The misalignment caused by bad mounts can put stress on transmission seals and connections, potentially causing fluid leaks that further harm transmission operation. 
• Drivetrain misalignment: A major failure can cause the engine and transmission to become significantly misaligned, which puts undue stress on other parts of the drivetrain and can lead to premature wear and tear. 

This video demonstrates the symptoms of a bad transmission mount, including excessive vibration and clunking noises: 59sAutoMotivateYouTube · May 24, 2024
Why it’s important to fix

• A bad motor mount is often a less expensive repair than a transmission rebuild, so catching the issue early can save you money in the long run. 
• Ignoring the problem can lead to more significant damage to both the transmission and other powertrain components over time. 

This video explains how to diagnose a bad motor or transmission mount: 1mChrisFixYouTube · Feb 26, 2014

At what mileage do motor mounts go bad?

Engine mounts can last anywhere from 50,000 to 100,000 miles or more, but their lifespan is highly dependent on factors like driving habits, road conditions, climate, and the quality of the mounts. Instead of a strict mileage, it’s best to watch for symptoms like increased vibrations, knocking noises, or a visibly tilted engine. Many OEM (original equipment manufacturer) mounts are made of rubber and are designed to be replaced within the vehicle’s lifetime.
 
This video explains factors that influence the lifespan of motor mounts: 52sLearnToDIY360YouTube · May 10, 2025
Factors influencing engine mount lifespan

• Driving habits: Aggressive driving, frequent hard braking, or driving on rough roads can cause mounts to wear out faster. 
• Climate: Extreme heat or cold can degrade the rubber components more quickly. 
• Fluid leaks: Leaks from oil, power steering fluid, or other engine fluids can accelerate the breakdown of rubber mounts. 
• Mount quality: Higher-quality or performance-oriented mounts may last longer than standard OEM mounts, which are often optimized for comfort. 

When to replace your engine mounts
Rather than a specific mileage, pay attention to these signs of wear:

• Excessive vibrations: You may feel more vibration in the steering wheel or seat than usual. 
• Noise: Listen for knocking, clanking, or other unusual sounds, especially when accelerating or shifting gears. 
• Visible damage: Inspect the mounts for cracked or broken rubber. 
• Engine position: Check if the engine appears to be sagging or tilted to one side. 

What to do

• Have your engine mounts inspected regularly, especially around the 75,000-mile mark. 
• If you notice any of the symptoms above, have a professional technician inspect them as soon as possible. 
• If one mount fails, it’s often recommended to replace all of them at the same time.