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Transmission Fluid Leak: What You Should Know!

Car Leaking Antifreeze And Overheating

Transmission fluid leak is one of the most common transmission problems.

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Your vehicle’s transmission is responsible for transferring the power from the engine to the wheels and, therefore, make the car move and speed.


If you noticed a puddle of a red fluid underneath your vehicle, this is a sign of transmission fluid leak.


Transmission leak can be due to a straightforward issue or due to major internal problems.


Overall, transmission fluid leak is not an emergency; however, you need to get it fixed to avoid further damages and, therefore, higher repair costs.


In this article, we will walk you through the leading causes of transmission fluid leaks. Also, we will discuss in detail ten symptoms of transmission fluid leak.


What Causes a Transmission Fluid Leak?


Many reasons can make your transmission fluid leaks, including:


  • Not Changing Transmission Fluid on Time


Every vehicle should change its transmission fluid regularly.


The vehicle’s owner’s manual should indicate how often one needs to change his fluid transmission vehicle on normal and extreme driving conditions. If you can do not have access to your vehicle’s owner’s manual, you can easily find it online.


Transmission fluid will pick up metal particles during the vehicle’s everyday life. These particles can add up, causing significant transmission, gasket, and seals wear.


Therefore, you must change the transmission fluid regularly to avoid damaging transmission parts and thus causing a fluid leak.


  • Accidents


Accidents cars cause many issues to your vehicle’s internal parts. Some of these issues could be a transmission fluid leak.


If the car was hit on the wheels or axles, there is a high potential of transmission fluid leak.


Any transmission has one to three output shafts. If one of these shafts got pushed hard, they can destroy the transmission or simply damage the seals causing the transmission fluid to leak.


If you observed pink fluid leaking out of your vehicle, you need to inform your mechanic and get it fixed immediately.


  • Tear and Wear


The most common reason for the fluid leak is a tear or wear in the internal transmission parts. It is not an easy task to identify which transmission part is responsible for the hole; therefore, you need a mechanic to be detailed diagnose the transmission to identify the first crack or issue.


Here are some of the common causes of transmission fluid leak:


  • The leak in Transmission Pan


Like any other vehicle part, transmission pan can wear and tear over time, causing a potential for a fluid leak. Moreover, transmission pan can get damaged if it got hit by a big rock in the street, causing fast transmission fluid leak.


Also, if the transmission plugs were not tightening enough, a fluid leak might occur. This usually happens right after transmission fluid change.


  • A leak in Fluid Lines


Fluid lines are usually durable as they are made of aluminum or steel. However, these lines might wear due to debris in the street or due to continuous high heat. Overheated fluid lines can have cracks causing the transmission fluid to leak.


A leaking fluid due to fluid lines issue is one of the fastest ways to lose transmission fluid.


  • Loose or Broken Seals


There are a lot of seals in the transmission, and it is tough to determine which one is causing the fluid leak. Therefore, if you think that there is an issue with the transmission seals, you should have a mechanic confirm which seal is causing the problem using specific tools and equipment.


In most cases, seals issues can either be in the input or output shafts. If not, then ask your mechanic to check the transmission pan, driver shaft, plug seals, sensors, shifter housing seal, valve body, speed odometer input seal, and the tail housing seal.


  • Transmission Pan Gasket Fails


Fails in the pan gasket can happen due to poor manufacturing, bad parts alignments when it was installed, and continuous high heat environments.


The good news is that fixing the pan gasket is not expensive. Therefore, it is recommended to get it fixed as soon as possible to avoid more damage and, therefore, higher repair costs.


  • The leak in Torque Converter


Transmission fluid is pumped throughout the system using the torque pump. If there is any leak in the torque pump, fluid won't move appropriately through the transmission system, and therefore, the vehicle will perform oddly.


Transmission Leak Symptoms


There are many ways to identify transmission fluid leak issue in your vehicle.


Here are ten symptoms of transmission fluid leak:


  • Use a Dipstick


You can check for a transmission fluid leak using the dipstick method.

The dipstick is located in the middle of your engine bay; it has a different color and has the word “trans” written on it.


Like how you check your engine oil, simply remove the dipstick, wipe it until its clean, insert it, and remove it again.


Dipstick check has to be done when the car is warmed up (e.g., after 20-30 min of driving plus setting the engine on idle in park.)


Good-standing transmission fluid should be a bright pinkish color. If the transmission fluid looks brownish, it means that the liquid is burnt, and you need to replace it very soon.


If the transmission fluid is lower than the appropriate level, add more transmission fluid. Do not overfill the transmission as this can cause transmission overheating.


  • Check the Dashboard Warning Light


Most modern cars are equipped with electronic systems that can tell you if there is an internal problem in your vehicle.

Usually, any internal error will show on your car dashboard as a light. One of these lights is the transmission light.


If the transmission light comes on, this is an indication of an internal problem in your transmission. You must take care of any transmission issue to avoid overheating and major failures in your car.


Check your car’s owner’s manual to get more information about what might cause transmission light to come on. If you don’t have your vehicle’s owner’s manual, you can easily find it online.


If the transmission light stays on, you need to contact your mechanic and have it fixed. Some people reach out to transmission specialists to avoid unnecessary repairs.


  • Observe Fluid Puddle Under the Vehicle


One of the easiest ways to confirm a transmission fluid leak is to observe a fluid puddle under your parked vehicle right when you move it.


Not every fluid leak means a transmission fluid leak. The transmission fluid usually has a distinctive color (e.g., pink or green) to allow you to identify it quickly. However, a pink or green fluid puddle does not also mean that the problem is in your transmission.


Although finding a fluid puddle under your vehicle is the most straightforward symptom of transmission fluid leak, it might be misleading as many of the internal systems (e.g., steering system) use the transmission fluid as their system fluid.


Therefore, you need to confirm that this fluid is coming out of your transmission, not from other parts.


  • How to confirm that the fluid leak is coming out of the transmission?


It is easy to locate the transmission by looking under your vehicle. However, it is hard to confirm the root of the fluid leak.


The easiest, short-cut is to take the vehicle to a transmission specialist or a mechanic shop. They will make the appropriate diagnosis, confirm the cause of the leak, and fix the issue.


Some people prefer to confirm the leak on their own. If you are one of those people, here is how to accurately establish a transmission fluid leak:


First, the fluid leak should come downward of your vehicle’s underside due to gravity. Also, fluid can be blown all over the place due to wind. Therefore, you need to make sure that the floor under the vehicle is immaculate, wipe the underside of your car.


Then, add a die to the transmission fluid; this way, you can monitor the die and see if it is coming out of the vehicle.


Make sure that the fluid is filled to the appropriate limit before driving. Then, you need to add some mileage to the car, which is the most time-consuming step.


The appropriate number of miles depends on the car type and the transmission leak severity. In some scenarios, you will see the leak right after 30-40 miles; however, in slowly leaking transmission fluid scenarios, don’t be surprised to see a fluid leak after 100 miles.


This is, of course, a lot of time and effort. A professional mechanic should have the required tools to identify the leak without waiting all of this time.


  • Listen for Grinding Gears


In general, if you hear strange, weird sounds in your car, the car might have internal problems. Therefore, never delay taking your vehicle to the mechanic.


When the transmission fluid is low, the car will not perform as usual, and sometimes it can cause gears grinding sounds. Grinding sound can mean significant transmission damage.


  • Listen for Clunking Transmission Sound


Another strange sound associated with transmission fluid leak is a clunking transmission. As we mentioned before, never delay taking the car to the mechanic if you experienced unusual sounds.


  • Check Any Strange Vibrations


In addition to the strange sounds in the vehicle, you might experience vehicle vibration due to slipping gears.


Usually, transmission switch gears happen instantaneously, and you will never notice it. However, in low fluid transmissions, the vehicle will have odd performance causing sudden acceleration and extreme slowness.


This strange car behavior can cause the vehicle to vibrate, indicating that it is not safe to be driven. Therefore, you must take it to the mechanic immediately.


  • Check for Burning Smell


A burning smell in your vehicle indicates an internal problem, usually, vehicle overheating.


Car overheating is not a good thing, and it can cause major internal problems and, therefore, costly repairs.


Whether or not the burn is related to the transmission, you need to get the issue fixed.


  • Monitor Car’s Acceleration


As we mentioned earlier, you should not notice when the transmission switches gears. If your transmission fluid is low, there will be a slow response in the shifting from one gear to the other.


Delayed gear shift response can cause slower acceleration. You can notice it when you press on the gas pedal and not see the engine moves as quickly as it should be.


  • Listen for Starnge Noise in Nuetral


Again, any strange noise in any situation is a warning of an internal vehicle issue.

If you noticed a bumpy sound when your car is on neutral, your transmission fluid might be low.


  • Check for Extreme Heat from The Transmission


Vehicle overheating is the last thing you wish to happen to your vehicle parts, let alone to your transmission.


If the transmission got overheated, you would notice some heat coming up through the vehicle’s floor. Keep an eye on the dashboard heat gauge and any other signs of car overheating.


If the car gets overheated, you will start smelling burn, indicating immediate repairs needed.


How To Prevent Transmission Leak


The transmission does a lot of things in your vehicle, and you need to ensure that it is performing correctly.


Low transmission fluid can cause issues that could be minor or major. One of the primary reasons for low transmission fluid is the transmission fluid leak.


There are some tips and best practices to avoid having the transmission fluid to leak, including:

  • Always check the transmission fluid level when doing an oil change.


  • Pay close attention to transmission fluid color. If it is bright and clear, the fluid is in good shape. If the fluid color is brownish burnt, then it might be a good time to change your transmission fluid.




Your vehicle’s transmission is responsible for transferring the power from the engine to the wheels and, therefore, make the car move and speed.


One of the main transmission problems is a transmission fluid leak.

A fluid leak can happen due to not changing the fluid often, car accidents, and wear or tear for the internal parts.


There are many ways to identify a fluid leak in your transmission, including but not limited to: seeing a pink fluid puddle under your vehicle, hearing weird sounds, having a vibrating car, and seeing warning lights on the vehicle’s dashboard.


Whatever the reason for the fluid leak, it is not recommended to drive your car on low transmission fluid as this can cause significant problems and higher repairs costs.

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