5 Symptoms of a Bad Transmission Filter

Most vehicle owners do not regularly change their transmission filters, let alone know the symptoms of a bad transmission filter. A bad filter can greatly reduce the life span of your car if it gets clogged with particles and abrasives.

Did you know that most manufacturers recommend that people change their transmission filters every 30,000 or after every two years? If your car happens to exceed these numbers, the transmission filter will start to go bad, gather dust particles, and affect your car’s performance.

The transmission filter is usually made out of a “felt material” and is found in the transmission system of your car. The transmission has some fluid that helps it run smoothly and efficiently. The filter is used to filter the fluid by trapping any particles that come in contact with the fluid thereby keeping the system clog-free.

However, if the filter gets clogged, contaminants will reach your transmission causing drivability issues and the related components to malfunction. Learning how to check the transmission filter and the symptoms associated with a bad one is straightforward and fairly easy to do.

In this article, we will talk about the symptoms of a bad transmission filter and answer the various questions you may have about transmission filters.

Symptoms of a bad transmission filterdirty transmission filter cause slipping

Leakages from beneath your car.

Pay attention to any leakages that may be found on your garage floor or your trail on the road. The best time to notice leaks is when you move your car from a parked position. Be sure to also look for any trails left behind your car, especially if you are experiencing drivability issues.

The first reason why the transmission fluid can leak is if the filter is not fitted properly. You may be asking yourself, “So what happens when the transmission filter is loose?” Well, the loose transmission filter symptoms include the aforementioned leakage in addition to strange noises in the transmission.

The seals and gaskets on the transmission system can also get worn out with time and mileage. The worn-out parts will result in a much weaker seal thus creating a leak.

Moreover, if a filter gets clogged, the fluid ceases to flow and ultimately accumulates in high amounts till it gets kicked out through the vent tube. Leaking transmission fluid can cause severe damages to the transmission system and is therefore recommended to fix the issue as soon as possible.

Dirty transmission fluid.

The obvious sign of a contaminated bad transmission filter is the presence of dirty transmission fluid. Over the industrial standard 30,000-mile range of operation, the filter will filter a lot of particles out of the transmission fluid but eventually get worn out. At such a point, the contaminants will be able to pass through into the fluid making it dirty.

Dirty transmission fluid cannot do the job properly. If left unaddressed, the fluid can start to burn to result in a full transmission repair. The next time you check your transmission fluid, don’t focus on the fluid levels alone, pay attention to the quality of the fluid too.

Symptoms of dirty transmission fluid include the presence of dirt and metal shavings in the fluid. The fluid may also look dark or milky.

Contaminated transmission fluid will inevitably affect other parts of the vehicle such as the transmission cooler. The cooler helps in cooling the transmission fluid which passes through it. A dirty fluid will clog the cooler lowering its efficiency.

The clogged transmission cooler symptoms may include the presence of deposits on the part and/or having a hot transmission fluid.

Strange unexplainable noises.

There are very few things that drivers hate more than their vehicle making strange unexplainable noises. If the transmission filter is bad, there won’t be enough lubrication for internal components to work properly.

The inclusion of dust and deposits in the system will cause the components to move rigidly due to the restriction caused by the dirt.

Needless to say, the components will have more resistance resulting in strange noises as they move. A bad transmission filter is not the only cause of these sounds of course.

Strange noises can be caused by a loose exhaust hanger, a faulty suspension, a damaged catalytic converter, or torn brake pads. Check out the mentioned parts before narrowing them down to the transmission filter.

The most noticeable noise will be heard when you shift from park to reverse or drive. The shifting procedure is normally smooth and does not make any noises. Therefore, any time you hear a strange noise when shifting in that manner, know that there is something that needs to be fixed.

Your car is normally inaudible when you are sitting in neutral gear. However, if the transmission filter is bad, you will notice that your car has a noisy neutral. The noise will sound like the engine is changing gears without actually engaging them. A recurring noisy neutral will almost always point to a severe problem.

The noises in an automatic transmission may also be whiny, whirly, and high-pitched when you shift from park to drive. On top of that, the movement of the vehicle will feel jerky and awkward when you hear these noises.

Inability to change gears.

If the transmission filter is working properly and there are no issues with the fluid, your car will shift gears smoothly and effortlessly. In case the filter gets damaged, shifting gear will become a tedious and quite annoying task to do.

A bad transmission filter will cause your gears to grind on each other and your vehicle to surge when you try to shift gears. You will also feel some hesitation in the shifting and more resistance that will make shifting your vehicle’s gears a terrible experience.

Smoke and unusual burning smells

As mentioned earlier, when the transmission fluid gets too dirty, it can become hot and start burning. The hot transmission fluid will give out an unusual burning smell that can be easily smelt by the driver or mechanic.

A burning smell is the worst of these bad transmission filter symptoms. It shows that the filter has been bad for a much longer period than any of these other symptoms.

FAQs (Frequently Asked Questions)

how to unclog a transmission filter

Q: Can a clogged transmission filter cause gear shifting problems?

If the transmission filter gets clogged, it will allow more dirt and contaminants to enter the transmission fluid. Dirty transmission fluid will deposit particles on the gears making it had to shift between them.

Q: What happens if you don’t change your transmission filter?

Transmission filters are designed to be used for a set period. They are meant to be replaced on a given basis and not last forever. When the period ends, your filter will have gotten so dirty and clogged that it won’t be able to work properly.

The result of this will be weird noises when shifting gears, leaks under the transmission, and general performance issues. So, is it necessary to change the transmission filter? Definitely yes.

Q: Will a transmission flush clean the filter?

A transmission flush is meant to completely remove the old transmission fluid in the system by replacing it with new transmission fluid. This procedure entails the replacement of the fluid and has nothing to do with the transmission filter.

However, new fluid can help increase the lifespan of the filter.

Q: Should I change my transmission filter?

If the filter has been used past the 30,000 miles range, then yes, you should change it. You should also change it if you happen to notice any of the mentioned symptoms. Check-in with your mechanic if you are unsure.

Q: What happens if the transmission filter falls off?

The transmission fluid won’t have a filter to trap impurities, particles, and abrasives. Your vehicle will still run for a week or two, but it is not recommended because your transmission system will be damaged. Damaged to the point that you will have to replace the whole system.

Q: How to check transmission filter

After jacking up your vehicle, drain the transmission fluid through the transmission drain plug. Unscrew the bolts from the transmission pan and separate them from the transmission. Proceed to separate the gasket seal from the transmission and this will finally get you to the filter.

Unscrew the bolts holding down the filter and take a look at its condition. Compare its condition to that of a normally functioning one to figure out its state.

Q: How to unclog a transmission filter

After disassembling the filter from the car, spray them with disc brake cleaner to remove the contaminants. A toothbrush will also help in removing anything that may stick to the filter.

Final thoughts

Paying attention to the symptoms of a bad transmission filter can save you a lot of trouble and lower your repair expenses. Taking care of your filter should be easy and straightforward because the filter can last for years without needing any serious attention.

Use these symptoms to keep an eye on the filter and save yourself the time of having to go to a mechanic.

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Hi there, I am R. Hasan Tito, a mechanic, and owner of this website. My friend and I created this website to share our knowledge, expertise, and experience with our fellow mechanics' community and car users. I am a specialist and certified automotive mechanic (Both Heavy Commercial and Private Cars). I worked as a Mechanic and Mechanic Supervisor for over fifteen years at Global Rebound Automotive companies - Toyota, TATA, BMW, Nissan, TVs, and Others. Now, I enjoy my new role of leading a team of automotive experts (in their respective fields) and publish new content on a regular basis on my website and social media.

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