Did you notice a fluid leak on your driveway, which seems to come from the automatic transmission, or are you just tired of refilling the transmission fluid?
Then it is definitely time to repair your transmission fluid leak. Repairing transmission fluid leaks does not have to be very expensive, and in most cases, it will be surprisingly easy.
In this article, we will discuss the most common causes of a transmission fluid leak and how much it costs to repair it.
6 Causes of Transmission Fluid Leak
- Bad Transmission Pan Gasket
- Cracked or rusty transmission pan
- Leaking transmission pan drain plug
- Bent transmission pan
- Leaky Transmission fluid pipe
- Clogged transmission ventilation
Here is a more detailed list of the most common causes of a transmission fluid leak.
Bad Transmission Pan Gasket
A leaking fuel pan gasket is the most common cause of a leaking automatic transmission. The gasket should be replaced every time the transmission pan is removed on most car models, but many people install the old one again. This can lead to leaks very soon.
It also happens that they get old and start leaking because the transmission fluid is slowly eating them.
Some car transmission models use a sealer instead of a gasket, which can also get worn and need a replacement.
Cracked or Rusty Transmission Pan
Another common cause of a leaking transmission is a cracked transmission pan. A cracked transmission pan do usually happens if your transmission has an aluminum transmission pan. This can happen if you, for example, hit a hard object under your car on the transmission pan while driving.
Rust is a problem if you have a steel transmission pan. The pans are pretty thin material-wise, and if they start to rust, it will create a whole pretty fast. Check for any signs of rust, and if you find any, it is probably time to replace the pan.
Leaking Transmission Pan Drain Plug
Not all automatic transmission has a drain plug, but some do, and if you have one on your transmission, it is likely leaking. You usually find an O-ring sealing on the drain plug, which should be replaced after each fluid replacement.
Most people do not replace this O-ring sealing when they change the fluid, resulting in a leaking transmission after a while.
Bent Transmission Pan
If someone before you replaced the transmission fluid and had problems removing the pan because of strong sealant, for example, the pan might be bent around the edge.
The steel transmission pans are pretty weak, and if someone took a big screwdriver to remove it, there is a risk that they bent it. Check for any damages around the edges of the transmission pan. If it is bent, you maybe have to replace the transmission pan completely.
Transmission Fluid Pipe
A not of automatic transmissions do also have fluid cooling – not all of them, though. If you have a cooled automatic transmission, you will most likely have fluid lines going to the transmission cooler in the front of the car.
These lines are made of steel and tend to get rust holes and start to leak. They are also going very near the pan often, so you might think it is a leak from the pan but is coming from the transmission line above.
Clogged Transmission Ventilation
Most automatic transmissions have some type of open transmission ventilation on top of the transmission to ensure it will not build too much pressure inside of it. These small transmission ventilations can get clogged on some car models, which will create transmission leaks everywhere.
Look at the top for your transmission of some ventilation hoses, or ask your authorized dealer if your transmission has ventilation. Because they are installed on the top of the transmission, they can be difficult to reach.
Transmission Fluid Leak Repair Cost
Transmission fluid leaks do often not have to be expensive since most are small repairs.
Mostly a transmission fluid leak repair will cost 100$ to 300$ in material and labor work.
Here are some examples of repairs that could fix a fluid leak cost. The prices include parts, new fluids, and labor work. The prices can differ heavily depending on your transmission model, but it gives you a clue.
|Type of work||Price|
|Transmission Gasket Replacement Cost (Including Fluid & Filter)||150$ to 400$|
|Transmission Pan Replacement (Including Fluid & Filter)||250$ to 500$|
|Transmission Pan Drain Plug Replacement||20$ to 50$|
|Transmission Fluid Line Replacement||50$ to 200$|
Is It Safe To Drive With A Transmission Fluid Leak?
If you are sure that the transmission fluid level is good, you won’t damage your transmission with a small leak. The best practice is to repair the leak as fast as possible, though.
The more you drive a car that is leaking fluid, the more the fluid gets drained. At some point, you will not have any left, and your transmission will get damaged. If the leak is small, it can buy you time to dash to the nearest service station for repairs.
Of course, it is terrible for the environment to have a transmission fluid leak, so it should be repaired as fast as possible.
Hi, I’m Magnus, the owner and the writer of Mechanic Base. I have been working with cars for 10 years, specialized in diagnostics and troubleshooting. I created this blog because I was tired of finding false information on the web while looking for repair information. I hope you enjoy my content!