Transmission slipping is one of the more common signs of major transmission problems out there. Not only is it annoying, but it also poses a safety hazard. That is why we take it extremely seriously and personally do not tolerate any slipping from the transmission in my W211 Mercedes E-Class. We do not want to sound extremely pessimistic, a transmission slip is nothing more than an indication that a certain component in your transmission needs attention and fixing. The key thing here is not to ignore the initial signs and symptoms of a slipping transmission. As is with all things related to the automatic transmission, the problems do not go away on their own. On the contrary, we would say that the longer you ignore transmission problems, the more damage is being done and the higher will the repair bill be.
If you are reading this, you are already better than 90% of car owners that like to ignore transmission problems, and then it is always the car’s fault and never theirs. Go figure. Stay with us and learn everything a car owner should know about the transmission that slips during gear changes.
We recommend you also read our article about the 14 most common signs of transmission problems and our article on why a transmission starts shifting hard.
This article is based on standard hydraulic transmissions. If you drive a DSG (direct shift or dual-clutch automatic transmission) – Read this guide on DSG problems.
If you drive a car with a CVT transmission, read the article about the 9 most common CVT problems.
How Do You Know If a Transmission Is Slipping
We would like to say that if your transmission is in fact slipping, you would know exactly when this happens. It is just that obvious. But because that is not the best explanation, here is a better one.
If your transmission is slipping, the main thing you will notice is that your car is not responding to your input. As you press the gas pedal, the car will rev up but it just won’t move as it should. Instead, it will hesitate, and then after a few seconds, as the transmission stops slipping it will accelerate normally. It almost feels like your wheels hit a sudden ice patch. You can feel the engine revving but at the same time, it feels like it has shifted to neutral.
Slipping can occur as soon as you try to drive off in Drive or when your transmission shifts in between the higher gears. We have found that slipping most commonly occurs as the transmission shifts from 2nd to 3rd gear and vice versa.
Symptoms Of A Slipping Transmission
There are numerous symptoms that can either happen before the transmission starts slipping at the same time it is slipping or after a prolonged time of undiagnosed transmission problem. Here are the most common symptoms of transmission slipping:
- Delayed delivery of power
- Jerky shifting
- The weird odor of burning oil or metal
- Difficulties shifting into drive or reverse
- Engine revving with no drive
- Weird noises coming from the transmission
- Check engine or transmission warning light
If your transmission is slipping, the sensation can be best described as delayed delivery of power. Let’s say you step on the gas pedal, wishing that the car would eventually shift from 2nd to the 3rd gear. Instead of shifting instantly, the car gets caught up during the shift, the engine revs up but the third gear is only activated after a few long seconds. During that time you can feel how the power is being wasted as if it is slipping away during the gear change.
As the transmission finally changes the gear, the entry to the 3rd gear is not as smooth as it should be. Due to the increased engine revs, the gear change is jerky and rough. During this time, the entire process of shifting can be accompanied by whining, grinding, or other metallic noises. This indicates internal transmission damage and problems. Although rare, you will also be able to sense an odor of burning oil or transmission fluid. This indicates that the transmission internals is either not being lubricated properly or that there is not enough transmission fluid in the first place.
One of the symptoms related to transmission slipping is also delayed engagement or no drive as you shift into drive and rev up your engine. This is a more serious symptom that usually occurs after a driver has been successfully ignoring the transmission slippage problem for an extended period of time. If the transmission slipping is evident to the electronics of your car, the car should alert you of problems by igniting the “check engine” or “check transmission” warning light.
What Is The Cause For A Slipping Transmission?
There is no simple answer to this question. There are numerous reasons why transmission can start slipping and they range from electronic problems to mechanical wear and lastly problems related to both the quantity and the quality of the transmission fluid. Below are some of the most common reasons for a slipping transmission that we found:
- The quantity and quality of the transmission fluid
- Problems with the clutch
- Torque converter problems
- Worn-out interior transmission parts
- Worn-out transmission bands
- Electronic and solenoid problems
We are constantly going on about the importance of transmission fluid. Or better yet, the importance of transmission fluid changes. The number one thing you can do to avoid transmission problems, including transmission slipping, is replacing the transmission fluid and flushing the transmission. Most car manufacturers predict a strict transmission fluid change interval that should never be ignored. If you own one of those cars that come with lifelong transmission fluid, do not be fooled, you still need to replace your transmission fluid and transmission filter at a regular interval. This interval is usually every 40,000-70,000 miles. It varies by the type of transmission and your driving habits. Make sure you also have your mechanic check the state and level of transmission fluid in between the transmission fluid replacements.
An insufficient amount of worn-out transmission fluid can also lead to increased wear of the internal gears and other transmission components. A transmission can start slipping as a consequence. Worn-out and rounded gears can be hard to engage and synchronize which results in slipping, hard shifting, and jerking. Additionally, broken or worn-out transmission bands can also be at fault for slipping. Transmission belts are responsible for linking the gears and assuring the smoothness of the shifting process.
Just like a car with a manual transmission, an automatic transmission also comes with a clutch (but no clutch pedal). Together with the torque converter, the clutch in the automatic transmission is dependent on the transmission pump and shift solenoids to receive a steady flow of pressurized transmission fluid in order to trigger smooth gear changes. If the clutch is faulty or damaged, the entire process gets rough, jerky and delayed which results in slipping of the transmission. The same is true for the torque converter. A damaged torqued conversion will impact the power delivery and shifting. Read more about torque converters here.
In many cases problems with the conductor plate, the TCU (transmission control unit) or shift solenoids are responsible for a slipping transmission. Shift solenoids control the stream of transmission fluid to different parts of the transmission based on the data received and processed by the TCU. The TCU essentially tells the solenoids to push the flow of transmission fluid to enable a smooth gear change into the desired gear. If any of these components fail, or if there is not enough transmission fluid to direct by the solenoids, the driver is soon met with very noticeable changes in the shifting behavior. Read more about shift solenoids here.
How To Stop My Transmission From Slipping
We need to be real and honest with you. There is no easy, DIY, or at-home quick solution for a transmission that is slipping. Even if there is, it is surely not long-lasting or good in the long run.
The only way to stop transmission from slipping and fixing the underlying cause is to visit a professional workshop. The first step they will take is going to include a test drive and a professional diagnostics tool that will detect any of the electronic problems we mentioned earlier. If there are no error codes on that part. The transmission will need to be opened and diagnosed further.
Once they determine the underlying cause for the slipping, a replacement part, a simple transmission fluid flush, or an adjustment of the transmission bands will be executed. We have seen plenty of cases where a fluid flush was all that transmission needed to start working optimally again. However, there are cases where a serious degree of mechanical wear of the transmission internals was reason enough to rebuild an entire transmission.
How much does it cost to fix transmission slipping?
The cost of repairs greatly varies depending on the damage that is causing the slipping of the transmission. Sometimes a simple transmission software update for 100$ can resolve the issue or a 300$ transmission fluid flush and replacement. In other cases, a complete rebuild of the transmission is needed which will cost you anywhere from 1500$ to 3500$.
Can A Transmission Flush Fix Slipping?
Indeed it can. Sometimes the sole reason why your transmission might be slipping is the poor lubrication provided by the old or worn-out transmission fluid. If you are lucky enough to not cause any other damage to the transmission, replacing the transmission fluid can fix the problem.
Can Transmission Fluid Additives Stop The Transmission From Slipping?
Any professional who is not also an additive salesman will tell you that no, no additive on this planet is not capable of fixing the underlying cause for transmission slipping. If you read the fine print of these additives, it clearly states that they should be used for the prevention of slipping. A transmission fluid additive is unable to resolve the damage that is causing your transmission to slip.
Frequently Asked Questions
How Long Can You Drive With A Slipping Transmission?
It is not a question of how long can you drive with a slipping transmission, should you drive with a slipping transmission is the real question. And the answer is no, the moment you notice that your transmission is slipping is the moment you should seek professional assistance. The longer you drive with a transmission that slips, the more risk you are taking on.
How Long Does A Slipping Transmission Last?
There is no definite answer, but one thing is for sure, the longer you let the slipping go, the more damage there will be. Eventually, the transmission will face a complete breakdown and you will face a big repair bill.
My Transmission Is Only Slipping When It Is Cold Or Hot, Why?
Cold weather poses a big hurdle for your automatic transmission. The transmission fluid thickens up, which restricts the flow rate. Seals on the transmission can seize and shrink which leads to fluid leaks and potential loss of pressure. These factors can all lead trigger the transmission to slip. As the transmission warms up, the slipping should stop. If it does not, visit a mechanic.
If your transmission slips in hot weather, it is most likely because of overheating. Extreme temperatures contribute to the overall operating temperature of the transmission which can lead to the transmission fluid becoming runny and less viscous. This is especially common if your transmission fluid is already worn out or old. High temperatures only amplify the problem and your transmission can start to slip.
Can Overfilling A Transmission With Transmission Fluid Cause It To Slip?
Yes, overfilling the transmission with transmission fluid can make the transmission slip. The exceeded amount of transmission fluid starts mixing with air, creating a froth or foam in the oil sump. This leads to transmission problems, including slipping.
Can Low Engine Coolant Cause A Transmission To Slip?
While it is extremely rare, yes a low engine coolant level can be connected and responsible for a slipping transmission. The engine coolant’s job is to pass over the transmission cooler in the radiator. During this process, the transmission gets rid of the excessive heat which allows it to work properly. If the coolant level is too low, the transmission is not going to get cooled off as it should. The overheating of the transmission comes as a consequence of low coolant levels. Overheating can lead to transmission problems, including slipping.
Can A Bad Transfer Case Cause The Transmission To Slip?
Yes, a bad transfer case can impact the behavior of the transmission. It can indeed cause it to slip. Read more about the symptoms of a bad transfer case.
Can Bad Spark Plugs Make Your Transmission Slip?
No, bad spark plugs cannot in any way cause the transmission to slip. There is no connection that would theoretically make sense for bad sparks to cause transmission problems.
My Transmission Is Slipping But There Are No Error Codes On The Diagnostics?
A slipping transmission can sometimes show up error codes on a diagnostics tool. However, if the damage is purely mechanical and cannot be detected by sensors, there is a possibility that no error codes are shown during the diagnostics process.
My Transmission Slips When Turning, Why?
There is no specific reason why your transmission tends to slip when turning. Your transmission is slipping because of transmission-related problems such as low transmission fluid, worn-out transmission fluid, solenoid issues, torque converter issues, worn-out transmission bands, etc. Turning has nothing to do with these problems.
My Transmission Slips Going Uphill, Why?
Your transmission is slipping when going uphill because of transmission-related problems such as: low transmission fluid, worn-out transmission fluid, solenoid issues, torque converter issues, worn-out transmission bands, etc. Driving uphill and shifting at the same time puts an additional amount of stress on the transmission which amplifies transmission problems.
Can A Dirty Transmission Filter Cause Slipping?
Most definitely. A clogged transmission filter is amongst the most common reasons for a slipping transmission. A clogged transmission filter will limit the transmission fluid flow to all the crucial parts of the transmission that take care of smooth shifting.
There is nothing more to add. Just change your transmission fluid and filter on a regular basis and you can easily avoid 90% of the problems we listed above. We are not joking. All the best!