Have you ever been driving an automatic vehicle and pushed the accelerator pedal to the floor, but your car didn’t seem to be traveling as fast as you thought it should? You may have experienced what’s called “slipping.” But why would the automatic transmission slip when accelerating?
Automatic transmission slips when accelerating due to low or dirty transmission fluid, worn-out seals or bands, clogged filters, damaged torque converters, and solenoid problems. Easy fixes include replacing or topping up the fluid, cleaning the filters, and replacing the damaged parts.
If your car is slipping when accelerating and you need practical fixes to the problem, keep reading. You’ll learn how to fix these issues and how to keep your transmission working for a long time to come.
Causes of Automatic Transmissions Slipping
As their name suggests, automatic transmissions feature gears that shift automatically as the vehicle accelerates or decelerates.
However, when they start to slip, the acceleration rate reduces, frustrating drivers. Therefore, it’s crucial to know the causes of automatic transmission slipping so that you can take corrective action.
Here’s a rundown of the most common causes of automatic transmission slipping.
Low Transmission Fluid Level
Transmission fluids play a vital role in the smooth functioning of automatic transmissions, and coat, cool, and lubricate the gears. Therefore, if your car doesn’t have enough fluid, the gears won’t properly engage, causing the vehicle to lurch or “skip” forward.
In general, the symptoms of low fluid levels include:
- The car refuses to go into gear or goes into gear slowly.
- The engine revs up, but the vehicle doesn’t move.
- A burning smell when the car is running.
- Gurgling noises when accelerating.
Read: Why Speedometer Is Not Working and Transmission Is Not Shifting?
Dirty or Contaminated Transmission Fluid
Besides the fluid level, fluid quality plays a role in the proper operation of automatic transmissions. Transmission fluid can become dirty or contaminated from normal wear and tear and external factors such as dust, debris, or water. If the fluid is dirty, it can’t adequately lubricate or cool the gears, leading to slipping.
Besides slipping, here are some signs that you need to change your transmission fluid:
- Your transmission makes a strange hissing or gurgling noise.
- The car doesn’t accelerate as quickly as it used to.
- There’s a sudden loss of power while driving.
Read: Why Your Car’s Transmission is Slipping & Fix
Worn-Out Transmission Seals
Transmission seals keep the fluid in and contaminants out. However, as seals wear out, they become brittle and crack, leading to fluid leakage. If this happens, the fluid level drops, and the gears won’t get sufficient lubrication, causing the automatic transmission to slip when accelerating.
Additional signs that you should replace your transmission seals include:
- There’s a puddle of fluid under the car.
- The transmission is noisy.
- The car doesn’t shift gears smoothly.
- The car has trouble accelerating or maintaining speed.
Clogged Filters or Screens
Automatic transmissions include filters and screens to prevent dirt and other particles from entering the system and damaging the gears. If dirt and debris clog these filters, the gears won’t engage properly, causing slipping.
You can usually tell if you need to clean the filters when you see:
- The car hesitates when accelerating.
- The engine is revving, but the vehicle isn’t moving.
- There’s a decrease in gas mileage.
Read: Why is My Car With Automatic Transmission Jerking?
Worn-Out Transmission Bands or Clutches
Another reason your automatic transmission may slip when accelerating is that the bands or clutches have become worn out. When this happens, the gears won’t mesh properly, causing slipping.
In addition to slipping, here are some common signs that your transmission bands or clutches need to be replaced:
- The car shakes when accelerating.
- There’s a grinding noise when the vehicle is in gear.
- The car doesn’t move when you put it into gear.
Malfunctioning Torque Converter
The torque converter is a component in the automatic transmission that helps convert the engine’s power into torque, making the car move. If this component malfunctions, the transmission may slip when accelerating.
Here are some tell-tale signs that you have a problem with your torque converter:
- The engine revs, but the car doesn’t move.
- There’s a delay when shifting gears.
- The vehicle doesn’t accelerate as fast as it used to.
Read: Car Diagnosis Cost
Problems With the Solenoid Pack or Governor
The solenoid pack and governor are electronic components in the automatic transmission that help control fluid flow. If either of these components malfunctions, it can cause the transmission to slip when accelerating.
If you experience any of the symptoms I’ve mentioned above, chances are good that you have a problem with your solenoid pack or governor.
This YouTube video provides more insights into the causes of automatic transmission slipping:
6 Easy Fixes for Automatic Transmission Slipping
Now that you know some of the causes of automatic transmission slipping, let’s take a look at some easy fixes.
Caution: Before working on your car, park it in a safe place, turn off the engine, and let it cool first. This will help prevent accidents and injuries.
1. Check the Transmission Fluid Level and Quality
One of the easiest ways to fix automatic transmission slipping is to check the fluid level and quality. Ensure that the fluid is at the correct level and isn’t contaminated. If it is, then you’ll need to replace the fluid.
To check your transmission fluid level and quality, follow these steps:
- Put on your working gloves.
- Open the hood of your car.
- Locate the transmission dipstick. It’ll be a long, thin metal stick with a red handle.
- Pull the dipstick out and wipe it with a rag.
- Insert the dipstick back into the transmission and pull it back out.
- Check the fluid level. It should be between the two lines on the dipstick, or within the “HOT” range if you’re checking it when the car is running.
- Check the fluid quality. The fluid should be a bright red color and free of debris.
- If the fluid level or quality is low or contaminated, then you’ll need to top it up or replace it, whichever is appropriate.
2. Replace Worn Out Seals
If the transmission seals are damaged, you must replace them to fix the problem of automatic transmission slipping.
To replace the seals, you’ll need to:
- Put on your working gloves.
- Remove the pan from the transmission.
- Using a sealer and gasket scraper, remove the old seals from the pan.
- Apply a light coat of sealant to the new seals.
- Align the new seals with the grooves in the pan and press them into place.
- Replace the pan on the transmission.
- Tighten the bolts to the correct torque.
3. Clean the Transmission Filters and Screens
If the transmission filters and screens are clogged, then you’ll need to clean them to fix the problem of automatic transmission slipping.
To clean the filters and screens, follow these steps:
- Put on your working gloves.
- Remove the pan from the transmission.
- Remove the filters and screens and clean them with a solvent or degreaser. In this case, I recommend this CRC Brakleen Brake Parts Cleaner (available on Amazon.com). It’s non-flammable, non-corrosive, and quickly eliminates grease, oil, brake dust, and other contaminants.
- Reinstall the filters and pan in the reverse order of how you took them off.
Note: If the filters and screens are worn out, you’ll need to replace them.
4. Replace Worn Out Transmission Bands and Clutches
If the transmission bands or clutches are worn out, you’ll need to replace them to fix the problem of automatic transmission slipping.
To replace the bands or clutches, you’ll need to:
- Remove the pan from the transmission.
- Using a band installer or clutch installation tool, remove the old bands or clutches.
- Install new bands or clutches in the reverse order of how you took them off.
- Replace the pan on the transmission.
- Tighten the bolts to the correct torque.
Note: Ensure you consult your car’s owner manual to determine the correct replacement parts to install in your transmission system.
5. Replace the Torque Converter
If the torque converter is worn out, you’ll need to replace it to fix the problem of automatic transmission slipping.
To replace the torque converter, you’ll need to:
- Remove the pan from the transmission.
- Remove the torque converter and inspect it for damage.
- If it’s damaged, replace it with a new one.
6. Replace the Solenoid Pack or Governor
If the solenoid pack or governor is malfunctioning, you’ll need to replace it to fix the problem of automatic transmission slipping.
To replace the solenoid pack or governor, you’ll need to:
- Remove the pan from the transmission.
- Remove the solenoid pack or governor and inspect it for damage.
- If it’s damaged, replace it with a new one.
- Install everything in the reverse order of how you took them off.
Once you’ve completed these repairs, test drive your car to see if the transmission slipping problem has been fixed. If it has, great! If not, I recommend calling a professional to take a look.
Read: Why Car Won’t Start in Neutral?
When To Maintain Your Transmission?
Regular transmission maintenance can help prevent these problems from occurring in the first place. Here are a few guidelines that may help in this case:
- Change the transmission fluid and filter every 30,000 miles (48,280.32 km).
- Inspect the transmission bands and clutches every 30,000 miles (48,280.32 km).
- Inspect the torque converter every 120,000 miles (193,121.28 km)
- Inspect the solenoid pack or governor every 60,000-120,000 miles (96,560.64 – 193,121.28 km).
Key Takeaways
The causes of automatic transmission slipping when accelerating include low or dirty transmission fluid, worn-out seals, and clogged filters or screens. Also, worn-out transmission bands or clutches, a malfunctioning torque converter, and problems with the solenoid pack can cause slipping.
By following the easy fixes outlined in this article, you can correct the problem yourself. If these fixes don’t work, take your car to a professional mechanic for further diagnosis and repair.
