How to Find a Transmission Fluid Leak
If you have a reddish fluid leaking from your car, it might be a transmission fluid leak. This may or may not be a costly repair depending on what’s leaking. Follow this guide to find out what part of the transmission could be leaking and what you can do to fix it.
How to Diagnose Transmission Fluid Leaks
Symptoms of a Transmission Fluid Leak
Signs the Transmission Fluid is Leaking
- Smelly Dark Reddish Fluid Leaking From You Car
The first thing that you might notice when your transmission fluid is leaking is a strong, smelly, dark reddish fluid leaking from your car. Depending on where it’s leaking from, you could find the puddle either at the front, middle, or rear.
- Delayed Shifting or High RPM
Other symptoms include experiencing delays whenever you shift your car from Park to Drive or Reverse. The engine will rev up but the car will not respond. You may also notice a mismatch between the engine’s RPMs and the vehicle’s performance when going up a hill. When you hit the accelerator, the car does not move as fast as it’s supposed to.
There are several other symptoms that you may experience when you have leaking transmission fluid. These are just but the basics. The leak could be occurring at one of several places. Keep on reading to learn how to diagnose an automatic transmission fluid leak. We’ll show you some of the common places your ATF may be sneaking out of your transmission.
How to Diagnose Transmission Fluid Leaks
1. Check the Transmission Fluid Level
The best way to confirm that your transmission fluid is indeed leaking is to check its level. Since you’ll be dealing with a chemical, wear some eye and hand protection.
- Your vehicle should be at running temperature when checking the transmission fluid level. You can simply go for a ride and come back.
- Park your car on level ground.
- While the car is still running, pop the hood and locate your transmission dipstick. Most cars have it in red to signify the transmission fluid. Others have a fill plug that comes with a red or black cap on it. Whatever the case, grab onto your dipstick and draw it out. You’ll need to first wipe it clean with a paper towel before sticking it back in.
- Pull out your dipstick again and have a look at it. It should have two dots near the end with hatches in between. When your vehicle is warm and running, your transmission fluid should be in between these dots. It should be preferably closer to the top dot. If its level is way below the dots and hatches, your transmission fluid is very low.
A low transmission fluid level is evidence that you might have an external leak. You may even be able to see the fluid dripping to the ground. Other times, you may notice that there’s an accumulation of moisture and debris in certain places. Below are some of the common areas that you can check.
Common Places to Check For Transmission Fluid Leaks
1. Transmission Lines
If you found your transmission fluid dripping towards the front of the vehicle, check the transmission lines that connect to the radiator or transmission cooler. If there is a leak, you will notice moisture and a lot of debris that has accumulated on the lines. The fluid tends to attract dirt that sticks.
If you have an external transmission cooler, you’ll most likely have three transmission lines instead of two. Follow them right to where they connect to the transmission. Look for anywhere the transmission fluid is leaking.
2. Power Steering Fluid
Some vehicles recommend using the transmission fluid in the power steering system. In such cars, you will most likely not see anything dripping to the ground when the fluid leaks. You’ll need to check the power steering system for leakage.
3. Transmission Pan Gasket
The transmission pan gasket goes between the pan and the transmission itself. It can crack or become damaged when exposed to wear and tear or hot temperatures. This then causes the transmission fluid to leak.
If you see fluid around the pan, make sure to check the area above it as well. Sometimes leaks located above the pan gasket can run down and give you the impression that the gasket is leaking. This may not be the case.
Automatic transmissions have a selector shaft right above the pan that comes with a seal that leads into the transmission. It can also go bad. Other seals that you can also take a look at include the input seal that goes in between the engine and the transmission and the output seal which goes in between the transmission and transfer case, or the transmission and the rear-drive shaft.
4. Bell Housing
The bell housing is the part of the transmission that covers the flywheel and the torque converter. Sometimes it can cause transmission fluid to leak from the inside. Car manufacturers put small covers that you can pop out to inspect the leakage. If you see any red fluid pouring out, it’s likely to be your transmission fluid.
5. Tail Shaft Seal
When you move along the transmission towards the rear, you should find a tail shaft that has a seal that leads to the rear driveshaft. When the seal breaks or wears out, it may cause transmission fluid to leak. You’ll normally see it coming out of a weep hole or around the seal where it creates a mess.
6. Transfer Case
In a four-wheel-drive drive shaft system, your transmission fluid may be leaking where your transmission connects to the transfer case. This is caused by a failing transfer case seal. You’ll notice a lot of gunk in between that accumulates due to moisture.
In GM trucks, you may notice that your transmission fluid still goes low without any apparent leak. If you pull out the transfer case fill plug, the transmission fluid will come out under high pressure. This is still caused by a failing internal seal located between the transmission and transfer case.
As you drive your car, the transmission fluid pump pushes the fluid and forces it through the seal. The fluid fills up inside the transfer case with time. This is why it comes out with a lot of pressure when you remove the transfer case fill plug.
7. Any Part that Connects to the Transmission
Some front-wheel-drive vehicles have a transmission system that is built differently from that of a four-wheel-drive vehicle. As such, you may notice that you do not have a transmission pan. Some of the areas where the transmission fluid may leak include where the axle or any other part goes into or out of the transmission. There should a seal in between that prevents leakage. Check for any moisture and debris.
We hope that you found this guide helpful in figuring out where your transmission fluid is leaking from. The next thing to do is to check on 1A Auto for any replacement parts that you may need. This will help you fix your leaking transmission fluid as well as prevent pollution anywhere you go.