If your transmission is slipping, it is a very serious problem. It always gets worse in a relatively short period of time. You’ll want to find out what is wrong, and have it repaired quickly, before any further lasting damage can occur.
Transmission Slipping Signs
A slipping transmission is pretty easy to recognize. Here are the most common symptoms that one has started to slip:
- Higher RPM Than Usual– When the transmission slips, it is not transferring all of the motors energy to the rear wheels. When this happens, the tachometer jumps up as the RPM increases.
- Smell– As the clutches inside the transmission slip, they create a lot of friction. This friction gets them hot and you may notice an egg-like smell.
- Vehicle Won’t Move– Eventually the transmission may not be able to move the vehicle at all. If this is the case, the first thing to check would be the transmission fluid.
- Decreased Fuel Mileage– Since the transmission will no longer be able to efficiently transfer power to the rear wheels, fuel mileage will suffer.
What Causes a Transmission To Slip
There are many reasons why a transmission would slip. We have listed some of the most common ones directly below. When trying to figure out why it’s slipping, it’s wise to start with the fluid. Even if you know it’s full, you can use the color chart linked to below to determine if something is going on in the transmission itself.
1. Low Fluid
Low or no transmission fluid is one of the most common reasons that a transmission will slip. Transmission fluid lasts so much longer than oil that, often people don’t look at it at all.
Once it gets critically low, the transmission will begin slipping, as there is no longer any way for it to move the engine’s power to the rear wheels. During this stage, extreme damage is being done to the transmission as it slips. You need to fill the fluid back up to the proper level right away.
2. Bad or Burnt Fluid
Transmission fluid can deal with a lot of abuse. That being said, it can go bad and will no longer be able to do its job. Check it and look at the color. Most manufacturers use red fluid. This transmission fluid color chart will help you determine if the fluid is bad. Black fluid is an obvious sign that the fluid has been burnt.
3. Wrong Fluid
If you’ve recently serviced (or had serviced) your transmission, double check that the right fluid was put in. If it wasn’t, you’ll need to flush it and start over.
4. Transmission Bands
An automatic transmission uses bands to link its gears together. When these bands go bad the transmission will begin to slip. Sometimes they can be adjusted. Most of the time they’ll just need replaced.
5. Gears
Over time, the gears in a transmission can just wear out. When this happens, shifts will get rougher.
6. Solenoid(s)
Your transmission uses solenoids to control the amount of pressure going through the transmission. This affects shift firmness, whether it even shifts at all, and can make the transmission slip without enough pressure.
7. Torque Converter
If you feel like the transmission is only slipping a few hundred RPM on the highway, it may not be the transmission slipping at all. It could be the torque converter.
Modern torque converters use locking clutches to create a true 1:1 connection between the engine and the transmission. This helps fuel mileage. When they don’t lock, the engine RPM will be higher on the highway. Torque converters don’t typically lock until they are in overdrive or drive, or the vehicle reaches a certain speed.
Automatic Transmission Slipping When Accelerating
Slipping when accelerating is the most common way that a transmission will slip. This is due it being the most demanding thing on the internal components. Initially it’ll only slip under the heaviest of acceleration, but it will quickly get worse until the vehicle is un-drivable.
How to Fix a Slipping Transmission
Transmission repair is the most complex and difficult repair for even the most experienced shade tree mechanic.
1. Check the Fluid Level and Health
It’s important to start with the easiest to repair and most likely reason that anything happens. In this case that means making sure that the transmission fluid level is up to where it needs to be, as well as making sure that the fluid is healthy.
2. Check For Trouble Codes
There are many transmission related trouble codes that can tell you exactly what is wrong with the transmission. After that you just throw the code(s) back into google and see what is causing them.
3. Attempt the Repair, or Take it into a Shop
There are some things on an automatic transmission that you can fix yourself. Some sensors are pretty easy to get to. Say for instance, it’s clutch pressure sensor that has gone bad, that’s something you can often fix. On the other hand, if you are replacing clutches or a valve body, you’re going to be pulling the transmission and getting into some very difficult stuff.
Every article on this site is written from the perspective that you will be trying to repair your vehicle yourself, we will make an exception for this and recommend taking it into a shop, or just buying a rebuilt transmission before trying to rebuild it yourself.
Conclusion
Good luck figuring out what is causing your transmission to slip. If there is anything that you would like to add, please feel free to leave a comment below. Thanks.