Common Symptoms of a Bad Transmission Mount: All That You Need to Know

Your vehicle is a system comprised of various parts that all work in tandem. Like in all systems, there are major and “minor” parts. One of your vehicle’s major components is the transmission, which is responsible for the way your car moves. In some instances, a bad transmission can prevent your vehicle from working. The functionality of your vehicle’s transmission is significantly affected by the transmission mounts. So it is imperative that you know the symptoms of a bad transmission mount.

A lot of vehicle owners do not fully appreciate the significance of the bad transmission mount. You probably got here because you typed in the search query “what happens when you have a bad transmission mount” or something related. If that’s you, you are in for a treat because this article will focus on the significance of a transmission mount and how you can tell when your transmission mount is bad.

What is a Transmission Mount

Your vehicle’s transmission ensures that the engine and wheels turn at the same time. However, the transmission cannot execute this function without a transmission mount. Transmission mounts are small, light, and cost-effective mechanical parts responsible for many things that affect vehicle performance and, ultimately, your driving experience. They consist of a steel transmission mount bracket and a rubber bushing attached to the mount bracket.

symptoms of transmission mount going bad

Not all transmission mounts have rubber components. Some vehicles are built with fluid-filled hydraulic mounts designed to absorb the vibrations that rubber mounts cannot handle. They are more expensive than the rubber option and are arguably less durable; that is why fewer people opt for them.

As a result of its importance to vehicle performance, most vehicles have at least two transmission mounts depending on the vehicle. Regardless of the transmission mount location, it secures the transmission to the vehicle’s chassis. It does this by attaching the rear of the transmission to a welded support or bolted to the chassis.   

Besides securing the transmission, transmission mounts manage engine drivetrain vibration by ensuring that the linkages and driveshaft angles are accurate. This is why transmission mounts are crucial to how the car handles its engine vibration when the engine is running. So for this reason, the rubber transmission mounts are reinforced by metal components like aluminum. The rubber material used in transmission mounts is treated, highly durable rubber that has been temperature-optimized to withstand the engine’s drivetrain load.

Transmission mounts are also responsible for supporting the transmission’s weight while protecting the passenger cabin from engine vibrations. Although this article’s thrust is not a transmission mount vs. engine mount comparison, it is worth mentioning that both types of mounts are similar in purpose and design.  So a bad engine mount is just as bad as a failed transmission mount.

The transmission mount is either made from rubber or fluid, and it is designed to reduce contact and friction between the vehicle’s frame and the engine. Also, it minimizes engine movement when the engine is running, or the vehicle is in motion.

The thing with transmission mounts is that they perform a lot of tasks. That is why after a while, they experience wear and tear. Especially when the vehicle has high mileage. Such wear and tear can cause the transmission mounts to go bad, leading to excessive engine movement that can cause severe damage to the vehicle.

It is important that you make transmission mount replacement part of your vehicle maintenance culture. This is because regardless of the design and type of material used, transmission mounts can go bad at any point in time. Sometimes your driving style might lead to damaged or failed mounts. In other instances, it could be as a result of a vehicular accident or regular wear and tear. Whatever the reason is, you should not drive around with a bad transmission mount. Except you are looking to ruin your vehicle.

Symptoms of Bad Transmission Mount

A functional transmission mount is a key mechanical component in your vehicle. Conversely, a bad transmission can lead to severe vehicle damage if you do not take care of the situation early.

Thankfully there are symptoms that a bad transmission mount will reveal, and if you know what to look for, you might just save yourself from a whole lot of problems with your vehicle. So here are some of the symptoms of a bad transmission mount that you should watch for: 

common symptoms of a bad transmission mount

Thumping, Clunking, Bashing, and Banging Sounds

 These sounds are some of the more obvious signs that there is something wrong with the transmission mount. A functional transmission mount secures the transmission. A bad transmission does the exact opposite; that is why you hear these sounds. They occur because of the metals that hit each other as the unsecured engine shifts while the vehicle moves. The sounds are especially obvious when you shift transmission, accelerate,  go over a bump or step on the brakes.

Another reason for these sounds is that the bad rubber blocks between the vehicle’s chassis and the transmission mounts can transfer the vibration through the transmission mount into the vehicle’s chassis.

Steering Issues

If you notice that you have difficulty steering the vehicle around corners, then you might want to look up your transmission mount. The reason is that since a bad transmission mount cannot secure the engine, its movement will affect the way the vehicle negotiates corners. For example, an unsecured engine might move in opposite directions to where the vehicle is being steered to. The engine’s momentum will cause an imbalance in the weight and negatively affect how the vehicle moves.

A Moving Engine

Your vehicle was designed to move when the engine is running. One of the symptoms of a bad transmission mount is an unsecured engine that just keeps moving all over the place. This free movement is because the bad mounts fail to secure the engine within the engine bay. This is why as the vehicle vibrates while moving, the vibrations cause the engine to move all over the place. This movement is most obvious when the car accelerates, and it might be accompanied by any of the sounds you read about earlier. Pay attention to the engine movement whenever you rev the engine or accelerate while driving.

Damaged Components

When the transmission mount fails to secure the engine, it leads to excessive movement, which leads to the damage of other parts of the vehicle. One of the transmission mount components that is worst hit by wear and tear is the solid rubber part.

So if you notice that the rubber is either cracked or rotten, then your mount is bad. You might notice that the transmission linkages, hoses, and wiring are affected by this movement. This symptom might not be as obvious, but it is often indicative of a failed transmission mount. If you find that some of the wires are taut when the vehicle is in the drive, you might have a bad transmission mount.

Shaking and Excessive Vibrations

One unavoidable consequence of a bad transmission mount is the shaking that occurs when the vehicle accelerates. You will most likely experience a lot of vibration and repetitive knocking once you turn on the engine. You might also experience a lurching movement when you turn off the engine. If your vehicle has a front-wheel drive, then the shaking would be more of a back and forth rocking of the vehicle when you turn on the ignition. For rear-drive vehicles, the shaking is a bit more steady but sustained.

Damaged rubber blocks cause shaking on the transmission mount, which makes it difficult for the transmission mounts to manage the vibrations from the engine. The unabsorbed engine vibrations will cause the entire vehicle to vibrate excessively to the point where the driving experience is adversely affected.

A Distorted Engine Driveshaft 

This symptom is something of a domino effect of bad transmission mounts. The transmission mount is responsible for balancing and supporting the vehicle’s principal motor driveshaft. When the mounts are bad, the transmission gets damaged and distorts the engine driveshaft.

 A distorted engine drivetrain can lead to transmission shifting problems. So there you have the answer to the question can a bad transmission mount cause hard shifting? 

Transmission Misalignment  

One of the transmission mount’s functions is to ensure that the transmission is correctly aligned with the motor driveshaft.

Upon inspection of your vehicle, if you notice that the transmission lodging is no longer well-aligned, your transmission mount might be an issue. A badly damaged transmission housing damage is another indication that the transmission mount is bad.

How to Check Transmission Mount

Sometimes your vehicle might not even show any signs that the transmission mount is bad, so you should regularly check the vehicle to avoid dealing with unexpected transmission mount issues. This is because knowing how to check your vehicle’s transmission mount can save you from having to deal with problems with your vehicle. Here’s how to check engine mounts:

Listen For Knocking Sounds

Listen for a knocking sound when the engine is turned on or off. You could also hear a knocking sound whenever there is an engine load change. If you also notice that the engine tilts a lot when you rev the engine, then the chances are high that the transmission is bad.

Look Under the Vehicle

Jack up the vehicle until you can go underneath easily. Once you are under the vehicle, closely inspect the transmission mounts for loose brackets or loose/missing bolts. Loose brackets and missing bolts might not necessarily require replacements as you could fasten or replace the bolts.

While under the vehicle, check to see if you can find collapsed or rotted rubber or if the transmission mount has broken or is separated. It would help if you also looked out for cracks in the rubber. If you notice cracks or a collapse or rotting of the rubber on your vehicle’s transmission mount, you should prepare to replace it. For a visual presentation.

How to Replace a Transmission Mount

If your vehicle has shown some or all the transmission mount symptoms associated with a bad transmission mount, your best bet would be to replace it. There are two ways to do that. The first would be to get it done by an auto mechanic. However, since transmission mount replacement cost is often on the high side, many folks opt for the second option: the DIY approach.

To get your vehicle’s transmission mount replaced by an auto mechanic, all you need do is to run an internet search with the entry “engine mount replacement near me.” That should help you get in touch with seasoned mechanics near you.

On the other hand, if you opt for the DIY approach, then you would need the quality mechanic tools required to change motor mounts:

  • A breaker bar
  • Wrenches
  • Different sizes of extensions
  • A hammer
  • A pry bars
  • A flat-head screwdriver
  • Jack Stands
  • A jack(preferably a bottle jack)
  • A block of wood

How long does it take to replace motor mounts? Not very long, especially when you have gotten the hang of it. Once you have the required tools in your tools box, you can then proceed to replace the bad transmission mount. Here’s how:

Locate the Bad Transmission Mount

To do this park your vehicle on a flat, hard surface because it prevents the vehicle from rolling away when you are working on it. Locate the mount and then spray the bolts on the mount with penetrating fluid. Allow it to seep into the bolts for a few minutes before you loosen the bottom bolts using a breaker bar and short extensions. To loosen the top bolt on the amount, you might need to improvise using two wrenches. To do this, put the open end of the second wrench in the closed end of the wrench you are using to loosen the bolt. You will get something like an extended wrench that will provide more reach and torque.

Jack Up The Vehicle.

The next step would be to use the jack, and the jack stands to raise the vehicle high enough for you to get underneath it easily. But you need to know how to support the engine when replacing the motor mount. Pay attention to where you put the jack. Look for a solid piece of the transmission that wouldn’t get damaged by the jack’s pressure. The best place to situate the jack would be an area that does not have a seal. Once you have found one, fit the wooden blocks on the transmission, then jack up the vehicle slightly to remove pressure from the mount. This way, you can remove the already loosened bolts from the transmission mount. When you have done that, jack up the vehicle a little bit more so that you can easily remove the transmission mount.

Replace the Transmission Mount

Remove the mount from the bracket that it is attached to by removing the bolts at the bottom of the bracket. You then replace it with the new mount but ensure that it is a good fit. Before you apply the bolts, you might want to apply some thread locker on the bolts before tightening them as hard as you can.

To install the new transmission mount, slide it into position on the vehicle using a hammer and screwdriver to nudge it in. You might experience some difficulty as the new mount will be slightly taller, but you should avoid using force or you risk damaging the transmission mount. Jack up the vehicle a bit so that the mount is well aligned before fitting in the bolts and fastening them. After this has been done, lower the vehicle before you torque the bolts using a torque wrench or the extended wrench from earlier on. You can follow this guide for a visual presentation.

So at this point, you have probably asked yourself the question should I replace all motor mounts? Well, you might actually because in most cases, once one of the mounts fails, the other mounts are close to going bad too.

Final Words

As a vehicle owner, you must be able to recognize the symptoms of a bad transmission mount. This is because while your vehicle’s transmission mounts may not be the biggest or the most expensive part of the vehicle, it is essential to have a great driving experience. The transmission mount is meant to prevent vibrations and overcome the torque which the engine generates while running. So what happens when you have a bad transmission mount. Once the transmission fails, the vehicle’s performance is adversely affected, and over time severe engine damage might occur.

Your ability to identify these symptoms will save you a lot of repair costs and enable you to get the most from your vehicle in the long run.

Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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