Signs or Symptoms of low transmission fluid: Causes and Fixes

Did you know that if your mileage is between 30,000 to 60,000 then your car may be giving out signs of low transmission fluid?

I’m sure most of you may be worried after hearing that, but don’t worry, checking your transmission fluid levels and fixing it is easy. Your transmission fluid should not only be on the correct levels but also clean. Transmission fluid that has gone bad or isn’t in the correct amounts can lead to problems in shifting and engaging gears.

The purpose of the transmission fluid in your car is to cool and lubricate the parts of your transmission. It is also used to facilitate hydraulic pressures and actuators. All of this translates to a quicker and smoother transmission at all times.

In this article, we are going to tackle the causes and symptoms of low-transmission fluid to help you diagnose and fix the problem quickly.

What causes low transmission fluid?

It is prudent to keep an eye on several things that might cause your transmission fluid to go lower than the intended amount. Low fluid levels, if not addressed sooner, will eventually damage your entire transmission leading to a very expensive repair. The approximate value of fixing or replacing a bad transmission can set you back around $1800 to $3400.

With that said, make sure to pay attention to the causes to save yourself a trip to the mechanic. The causes may include:

symptoms of bad transmission fluid

A loose or faulty transmission pan.

The transmission system has a transmission pan that has seals and gaskets to tightly seal the system. The transmission fluid is well contained in the system by these seals, any damage or looseness in the assembly can cause fluid leaks.

The seals and gaskets on the transmission pan can get worn out with time and mileage. These weak seals and faulty gaskets will cause a weak seal on the system causing the fluid to leak. Additionally, the transmission pan can get cracked or punctured by road debris.

Make a regular habit of maintaining your vehicle by checking the structural integrity of the seals and the general condition of the transmission pan.

Dirty transmission fluid

Debris and contaminants from the environment can get through cracks and seals into the transmission system. The dirt will contaminate the fluid making it look brown, milky, or dark red depending on your normal transmission fluid color.

The dirty fluid will damage the system by wearing out the components with friction and bombardments. These wear and tears will lead to leaks and fluid loss. Dirty transmission fluid can also clog your transmission elements, thus preventing enough lubrication and flow to the elements that need it.

Cracked fluid lines

Even though the fluid lines are usually made out of steel and aluminum, they can sometimes break or get deformed. They may break because of accidents and exposure to a lot of heat.

Broken or cracked fluid lines will allow the transmission to leak faster than any broken seals. Moreover, the location of the lines and the fact that they are not easily accessible, make them harder to diagnose than loose seals.

A leak in the torque converter

In automatic transmission cars, the fluid is passed through the whole setup by the torque converter. The whole converter is durable and reliable that the components that usually get damaged are the torque pump and needle bearings.

Damaged torque pumps or needle bearings will not propel all of the transmission fluid. Some of the fluid will slip through the cracks in the damaged parts, leaking to the outside environment.

As you can see, all of these causes lead to fluid leaks. The transmission fluid levels can only go lower than the rated amount due to cracked, faulty, or loose components in the transmission system.

Signs of low transmission fluid

Leaks in the transmission system

From the causes mentioned above, you can tell that any leaks coming from your transmission system are a sign that the fluid levels will reduce.

The best time to notice leaks is when you move your car from a parked position. Make sure to check for any trails left behind your car, especially if you are experiencing drivability issues.

Difficulties in engaging or shifting gears

One of the first signs of low transmission fluid may be difficulties in shifting or engaging gears. The change in gears might also get slow with approximately two to three seconds of delay. This delay is prevalent when shifting into Drive and Reverse.

A delayed shift can indicate that the low fluid levels have impacted the hydraulic pressure which is needed to initiate the gear changes.

Shifting the gears can also become irregular with regular increases or decreases in responsiveness. Irregular shifts will cause inconsistencies in timing the shift and even making the shifts smoother. Also, if the transmission fluid levels get too low, the car will not be able to shift gears altogether. At this point, it would be advisable to take it to the mechanic since some parts may be severely damaged.

Gear slippage can be caused by low transmission fluid because the state makes it too easy to shift the gears. This is a dangerous problem because your transmission can slip out of gear at any time, all on its own.

The gears usually slip into the neutral position a few moments after switching gears. All of this is created by the fact that low transmission fluid will inevitably lower the hydraulic pressure needed for the transmission.

Strange noises

The only noise you should be hearing from your vehicle should come from the running engine or the exhaust. Any other noise, be it a beep, whine, or hum, shows a clear malfunction in the care system. If your car makes strange noises when accelerating, it may indicate an issue with the engine belt, exhaust system, or transmission.

If you are driving on low transmission fluid, you will notice the noises in combination with one or two more of these listed symptoms. In that case, it will mean that the noises are due to poor lubrication of the transmission components.

A loose torque converter can also cause these strange noises, the noises from this fault may sound like a rhythmic pounding. Listen to any grinding noises to differentiate this torque converter fault from the low transmission fluid. Low transmission fluid noises will indicate that there isn’t enough lubrication while a rhythmic pounding noise will point to a loose part.

Foul burning smells and transmission fluid color changes

Low transmission fluid will cause great friction between various parts. The effect of this is a build-up of metal shavings and inclusions in the transmission fluid.

The now dirty transmission fluid will get hot as it is being moved up and down the system. Eventually, it will start to burn, giving out a foul unusual burning smell that can be easily smelt by the driver or mechanic.

When you check the transmission fluid, focus on the fluid quality too. The transmission fluid color can also change from the usual pink or red to a dark brown, milky or dark red color. The cause of this is contamination, which will eventually lead to low transmission fluid levels if left unaddressed.

Low transmission fluid levels and contaminations will cause the entire transmission to overheat. The created friction raises the temperature of the fluid and moving parts. An overheating transmission can be diagnosed by the presence of smoke that will come out of the transmission area.

Complete transmission failure

The transmission will eventually fail if the fluid levels remain at their lower levels for extended periods. The combination of dirty transmission fluid, friction-afflicted elements, and loose parts will damage the transmission entirely.

Transmission failure usually happens due to negligence and untimely repairs. Several of the aforementioned signs will present themselves, long enough to give you a heads up about the problem.

How to fix low transmission fluid?

The first step to fixing low transmission fluid is to check the fluid levels using the dipstick. “The transmission dipstick looks like the oil dipstick and has an orange or yellow handle”. For those vehicles that don’t use dip-sticks, you will need to check your car’s manual or manufacturer’s website for more instructions.

The process is simple enough to be performed by a beginner and will take you around twenty minutes to two hours.

If this is your first time checking the fluid levels, then you will need mechanical gloves and maybe safety glasses for protection. The required tools include a funnel, a towel, and your car’s recommended transmission fluid. Here are the steps to follow:

  • Pack on a flat-level surface and start your car to warm the transmission. Look at your vehicle’s manual to make sure that the car is in Park or Neutral depending on the set standard.
  • Open the hood to locate the dipstick. Take it out and clean it off using the towel you have. We do this to ensure there is no oil on the stick when we measure the fluid levels. This helps provide a more accurate measurement.
  • After cleaning it, place it back into its previous location and remove it once more. Take a look at the fluid level indicators. There should be two of them; one for hot and another for cold temperatures. Depending on the weather, the fluid level should not be lower than the relevant indicator.
  • If the dipstick shows low fluid, then the transmission system leaks. Proceed to use the above signs to diagnose your problem.
  • After finding what the issue is, take it to a mechanic or fix it yourself if it is not severe. Proceed to get your car’s specific transmission fluid and use a funnel to refill the system via the filler tube.

driving on low transmission fluid

Frequently Asked Questions (FAQs)

Q: What happens when the transmission fluid is low?

Having low levels of the transmission fluid in your system will cause your gears to miss when engaging them. Moreover, it will cause a grinding sensation when shifting through gears. The resultant effect may lead your car to shake, Jerk, and make clunking noises.

Q: Will the check engine light come on if the transmission fluid is low?

A check engine light may turn on in some vehicles but won’t in others. This comes down to two factors; the type of car you own and the severity of the damage caused by low transmission fluid.

A few high-end cars have separate controllers that will set a code when the transmission fluid is low. Most vehicles will not set a check engine light on due to this fact. Low-end vehicles and a majority of others will only set the check engine light if other components in the car have been afflicted due to low transmission fluid.

Q: Can low transmission fluid cause jerk?

A good amount of transmission fluid in the system helps your car run smoothly when you shift or engage the gears. Low transmission fluid signs will make it hard to operate the gears, causing the car to jerk and lurch suddenly.

Q: Where do you add transmission fluid?

With your car’s specific transmission fluid in hand, take a funnel and put it in the opening from which you removed the dipstick gauge. Add the transmission fluid little at a time while checking the fluid levels with the dipstick. This is to prevent you from overfilling the system. Proceed till the right levels are reached, return the dipstick, and you are done.

Final words

Diagnosing and fixing low transmission fluid problems is a vital skill that every car owner should own. Considering that your transmission will always tell you it’s struggling before it fails, you should have no problem addressing this issue.

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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.

2 thoughts on “Signs or Symptoms of low transmission fluid: Causes and Fixes

  1. Hey Brian, I understand what you are experiencing with your 2011 Nissan Dualis.

    A complete stop of the CVT without preceding symptoms might not necessarily indicate a mechanical failure in the transmission itself. It could indeed be related to an electrical or computer system fault. Issues such as a malfunctioning transmission control module, faulty sensors, or electrical wiring problems can cause the vehicle’s computer to receive incorrect signals, leading to abrupt transmission behavior or even a shutdown.

    I would recommend the following:

    Diagnose the vehicle and pull out the registered faults codes to acertain what’s wrong with the vehicle.

    Check the transmission fluid.

    Check for any loose connections, damaged wiring, or corrosion that might be affecting the system.

    Given the complexity of CBT system, contact your mechanic to take a closer look and fix the issues.

  2. Great site. Some advice would be useful on how often / likely CVT gearboxes (in particular, a 2011 Nissan Dualis+2) just STOPS completely without any prior strange noises, slipping or other misbehaviour? I understand they are complicated, but such a sudden failure seems to me like it may be an electrical / computer fault rather than something mechanical?

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