Aside from lubricating purposes, fluids (ATFs and CVTs) play other essential roles in automatic and continuously variable transmission.
ATF in an automatic transmission, for example, lubricates the internal automatic transmission parts for proper operation, controls the workings in the valve body, and sends power and torque to the torque converter.
It is also a cooling agent in the transmission unit that keeps the transmission at normal operating temperature during operation.
During regularly scheduled maintenance, drivers with a continuously variable or automatic transmission may notice bubbles in transmission fluid when inspecting the state and level of the fluid.
Bubbles on the transmission dipstick indicate issues in the transmission. It may result in catastrophic damages if not handled on time.
The common causes of these bubbles are low or overfilled transmission fluid and air in the system. So, this article has provided sufficient information on the causes, symptoms, and how to remove bubbles from the transmission fluid.
Wait, scratch that! Let’s get high.
The Startling Link Between Transmission Fluid Bubbles and Car Performance
Transmission fluid is integral to the functions of gear shifting, lubrication of moving parts, and temperature regulation within the transmission. The presence of bubbles in the fluid can significantly compromise its ability to effectively fulfill these critical roles.
So here’s how a simple air bubbles in your transmission fluid can cripple your car’s performance.
#1. Transmission Fluid Lubricates.
Air bubbles in the transmission fluid affect the oil’s ability to lubricate moving parts. This can lead to excess friction in the transmission’s many moving parts. It can also cause gears to grind on each other depositing little metal flakes in the fluid.
#2. Transmission Fluid’s Role in Shifting Gears.
When you have air bubbles in the transmission fluid it can affect the transmission’s ability to transfer pressure to and through the valve body, which initiates the gear-changing process.
This can make it hard for the valve body and the TCM to activate the clutch packs and bands responsible for gear changes. You end up with the transmission getting stuck in one gear, or hesitating to change gears, finally shifting hard when the engine RPMs are too high.
#3. Transmission Fluids Role in Heat Management.
Air bubbles can prevent transmission fluid from efficiently flowing to the radiator and back, which can allow the transmission to grow gradually hotter.
This can be a double-whammy effect as transmission temperature continues to rise it can cause the fluid to degrade. This can further affect lubrication leading to a runaway heating effect which can damage many transmission components.
What Causes Bubbles in Transmission Fluid?
A car can be diagnosed with transmission problems when it exhibits symptoms of slipping, harsh engagement, or delayed gear changes. When these symptoms are detected, you should bring your vehicle to a mechanic right away.
A certified technician will diagnose the transmission problem by eliminating other possible causes of the symptoms and checking on several components of the powertrain system for fluid leaks or damage that could be causing faulty operation of the engine’s hydraulic system.
Here are some of the most common causes that may result in bubbles in transmission fluid:
#1. Air Leak in System.
One rather common cause for bubbles in the transmission is an air leak resulting from loose fittings, cracks, or damaged gaskets on any part of the vacuum or pressure lines connected to your car’s transmission, including the PCV (positive crankcase ventilation) valve and EGR (exhaust gas recirculation).
A release of air into the fluid can create bubbles, leading to the malfunction of the different components of the system.
#2. Pump Malfunction.
The second possible cause for bubbles in your transmission fluid is a defective or otherwise faulty air pump that contributes to internal contamination by allowing air into the powertrain system.
It may also contribute to damage of seals due to increased pressure within the hydraulic circuit.
If you are experiencing problems with your vehicle’s transmission related to this component, have it checked out right away by an experienced mechanic so he can check if there are any leaks or malfunctions present inside or outside of the system.
#3. Overheating System.
When the transmission fluid overheats, it may turn into vapor and enter the vacuum lines of your car’s PCV valve.
It can then be pushed back to the engine due to the pressure in the intake manifold where it will enter contact with hot air again, thus creating bubbles in your transmission fluid.
When this happens repeatedly, it results in a loss of power or poor shifting performance, which are sure signs that you should have your vehicle checked right away by an experienced technician at Your Mechanic.
He’ll quickly diagnose what is causing these problems and make repairs accordingly for the better overall performance of your vehicle.
#4. Clutch or Valve Body Malfunction.
Malfunctioning pressure control or pilot valve, or a worn-out clutch can also cause bubbles in the fluid. If one of these valves is stuck partly open, it will allow air to enter the system and create bubbles when it should normally be closed.
A worn-out clutch may result in improper shifting between gears due to internal damage which could prove to be expensive if not attended to right away by a professional mechanic who can diagnose and repair your car’s transmission problem effectively and efficiently.
#5. Corroded Solenoid Contacts.
The solenoid contacts on an automatic transmission might get corroded over time because of oxidation and other factors and eventually lead to electrical problems that affect the performance of your vehicle’s hydraulic system.
This can especially happen if the contacts are exposed to moisture because it will cause rust and corrosion more quickly.
When you notice that your vehicle is having trouble shifting gears or experiencing other problems related to the transmission, it’s important to bring it to a mechanic as soon as possible for a proper diagnosis of the problem and make repairs accordingly.
#6. Additives in Fluid.
Other causes of fluid contamination include additives like chlorine, borax, or soda ash put into your car’s automatic transmission fluid (ATF) by some service centers and quick lubes.
These chemicals can damage seals and gaskets over time, causing them to fail prematurely and thus creating bubbles in your transmission fluid.
This is another reason why you should never go to such places for oil changes or any other related service. You should instead rely on a reputable dealership or independent mechanic to ensure the proper performance and long life of your vehicle.
#7. Plugged Valve Body Filter.
A plugged valve body filter can also create bubbles in the fluid, as it will allow particles into your system that were normally filtered out by this component before being sent through to other components that need clean transmission fluid for efficient operation.
If you notice any shifting problems or difficulty with your car’s transmission, make sure to have it checked at once by an experienced technician who will quickly diagnose what is causing these issues and make appropriate repairs so everything works properly again.
#8. Leaking Hydraulic Fitting Seal.
This happens when there is a crack or damage to the hydraulic fitting seal that allows the fluid to leak out into the vacuum line, where it then gets sucked back into the intake manifold.
If this happens repeatedly, you can experience drivability problems or abrupt shifting between gears.
You should therefore see your car’s mechanic as soon as possible so he can diagnose and repair any damage to your vehicle’s hydraulic system quickly before more extensive repairs are needed.
#9. Clutch Seals Damaged.
Usually caused by overheating during hard driving conditions or racing, bubbles in your transmission fluid could indicate that there is a problem with the clutch seals that allow pressure release when the clutch is disengaging inside of the automatic transmission assembly.
Replacing them will require special tools and knowledge of how transmissions work which you won’t find at your local quick lube or another repair shop.
Instead, if you want to ensure quality repairs and proper performance of the transmission system in your car, use a professional dealer who will provide you with great customer service and answers to all of your questions.
#10. Reducing Fluid Level.
This is not actually the cause of bubbles in the fluid but rather a result of other problems that should be addressed as soon as possible by an experienced mechanic who can fully diagnose and address whatever might be causing these issues.
Symptoms include delayed engagement when shifting from park into drive, delays when accelerating from a stop, slipping gears during normal operation, or jerking movements while changing gears.
If you have been experiencing any of these but don’t know why they are happening, take it to a mechanic as soon as you can so he or she can determine what is going on and make the necessary repairs.
The earlier you do this, the more likely it will be that your transmission system will be repaired without additional damage being done which could potentially cost hundreds of dollars.
Even if you have been experiencing all of these problems, after receiving a proper diagnosis from a professional mechanic they should go away completely once any issues with your vehicle’s transmission system have been fully resolved.
If none of these options apply to your particular situation, then either there is air in the fluid trapped for some reason or there is an internal part failure related to the differential.
You need an experienced mechanic to come out and diagnose if bubbles are present in the fluid, and how prevention, diagnosis, or repair.
How To Remove And Prevent Bubbles In Transmission Fluid?
If your transmission fluid starts to show small bubbles, you can follow these steps to get rid of this problem:
#1. Get rid of the old fluid.
When you are not careful to let other additives seep into the transmission fluid or use the wrong type of fluid, causing air bubbles, the best remedy is to replace the entire fluid.
- Firstly, you need to check the color to know if the fluid needs to be changed or not. If your car’s fluid is red or pink, or light brown, it can still be used. If it is dark brown, milky brown, or has an unpleasant/pungent smell, the fluid needs to be changed.
- Preheat the engine before flushing the fluid. Draining the fluid in the automatic transmission is more complicated than diesel, so you need to flush the fluid at the bottom of the crankcase and also in the torque converter.
- Adding new transmission fluid that was recommended by the manufacturers.
How to change the car transmission fluid in each vehicle is different, so you need to pay attention to find out how your car should be changed. For some vehicles, it is necessary to completely change the fluid, but in some other types, only the lost fluid should be added and not replaced.
#2. Check the fluid level.
Inspect the transmission fluid to know the condition of whether the fluid level is too high or too low.
- In this case, if you check that there’s too much fluid in the tank, you can fix it by extracting the excess fluid. Two ways can help you do this process: the first is to drain it from below, and the second is to suck it in from the top. You can easily drain the fluid by unscrewing the drain plug. The advantage of this method is that it doesn’t cost you too much money to do it. But it will take a lot of time to prepare, and you don’t know exactly how much fluid you’re draining. To limit these disadvantages, the second method will help you. Using a liquid transfer pump makes it a lot easier to remove excess liquid. You can also use a temporary pump made from a large syringe and a rubber tube. Using these 2 methods can help you achieve your ideal transmission fluid level.
- In contrast to overfilling the fluid, you can easily repair the problem: when the transmission fluid is low by adding more fluid until it reaches the right level. On your car transmission, there are many details that are subject to friction as much as the engine. Transmission fluid is an indispensable catalyst, helping to lubricate, cool, and protect internal components to operate stably. If there is a shortage of transmission fluid, the car will operate very poorly, and even suffer major damage, along with many possible dangerous problems. You can pour more fluid by removing the dipstick, placing a funnel, and adding liquid into the tank. Remember to notice the level to make sure the transmission fluid is full (but not too much).
#3. Inspect the seals, gaskets, and filters.
Seals, gaskets, and filters are the major parts and play an important role in your car transmission.
When you detect something that happens to these components. You should replace them as soon as possible. Or you can take your car to the mechanic to have them check and fix it. Make sure the filter and seals are secure and all in good condition.
In some situations, when your gasket is damaged or broken, you can use the additive: head gasket sealer to quickly fix the leakages on the blown head gasket.
However, when using this additive, you should follow and check the instructions on how to use this product. When poured into the vehicle, it can react with heat, leaving powder deposits that accumulate over time.
FAQs.
Q: What are the symptoms of bubbles in transmission fluid?
At the initial stage, the air in transmission fluid symptoms, one will notice is a display of jolts and kicks when driving and shifting to a different gear range.
In any case, automatic transmission can jerk when stepping on the brake pedal. Regardless, it is appropriate to check your fluid level if the car starts to jerk when breaking because it could result from improper fluid level.
Other symptoms of air in transmission fluid include bubbles on the transmission fluid dipstick.
Q: How do I remove air from the transmission?
Having known the causes and symptoms of foaming transmission fluid, it is imperative to learn how to get the air out of transmission fluid.
Since there are several causes, there are also different ways to get rid of the bubbles. If the foaming results from a low fluid level, the best solution is to inspect the fluid and adjust it appropriately.
On most vehicles, you need to check the fluid level when warmed up and running at an average operating temperature. Other cars like Honda products require warning the engine to keep it at normal operating temperature but must be turned off before checking the fluid level.
If you see bubbles on the dipstick, check the overall conditions (viscosity, smell, color, transparency).
If you recently mixed the trans fluid, drain and replace it with a recommended fluid for your car. Do not continue driving with bubbles in transmission fluid. It can endanger your transmission unit.
Q: Are bubbles in transmission fluid normal?
Tiny bubbles in the transmission fluid are expected because the transmission incorporates reciprocating components that move inside the transmission fluid. But if the liquid is full of foams and bubbles, you’re probably driving with an overfilled transmission fluid.
Q: Should I change the brown transmission fluid?
A dark brown or black transmission fluid indicates a dirty, contaminated, or oxidized fluid that is incapable of adequately lubricating the internal transmission moving components.
Oxidation is bad for transmission fluid. It will damage system components if you fail to change them on time.
Q: Can I check my transmission fluid?
Yes. It is recommended to change your transmission fluid after covering certain miles. As alluded above, some vehicles require checking the transmission fluid when the engine is running at an average operating temperature.
Others require warming the transmission before checking the fluid after turning off the engine.
Consult your owner’s manual or service manual to know when and how to check your transmission fluid.
Q: Can too much transmission cause shudders?
The primary function of the transmission system is to lubricate the reciprocating system components and minimize friction between them. However, it won’t carry out this function properly if it is overfilled. The outcome will be shuddering transmission. Why is it so?
Overfilled transmission fluid will cause bubbling and foaming in the gearbox. This happens when the reciprocating parts submerge into the overfilled fluid. It then causes chemical reactions, resulting in transmission shuddering.
Q: Is it better to change or flush transmission fluid?
Transmission fluid change is a cheaper option that’ll help restore your transmission unit to running optimally. It is a quick-fix job that a car owner can do without consulting a technician.
In contrast, transmission fluid flush is costlier. It is a more complex job that needs professional attention and takes more time, but it’ll get rid of any contaminants that have been stored in the system.
Final word
Bubbly transmission fluid usually means air has gotten mixed into the fluid, a condition known as aeration. This often happens if the fluid level is too low, causing the pump to suck in air, or sometimes if it’s overfilled and churns excessively.
Aerated fluid doesn’t lubricate or cool effectively, which can lead to poor shifting, overheating, and eventually, serious transmission damage if not addressed.
In the article, we shared with you the cause and some methods to help you fix this problem. With this guide, we hope that you will have a deeper knowledge to know how to solve it when you experience this situation.