About the only thing worse than seeing that brown patch of oil under your car is seeing that pinkish fluid making its own special rainbow under your car. You are leaking transmission fluid. There are a number of reasons for this: some simple inexpensive fixes, some more involved and very expensive. The following are reasons why your car is leaking transmission fluid.
You may have a deteriorated transmission line
The transmission line carries transmission fluid from the transmission to the coolant system. This line can deteriorate over time and crack, causing a transmission fluid leak. If this is the case, the line will need to be repaired or replaced. You also need to check all fittings or clamps to ensure they are holding properly This is a relatively simple do-it-yourself repair and normally an inexpensive shop repair.
Transmission fluid pan gasket
Like the oil pan under the motor, there is a pan under the transmission that has a gasket that can wear over time. Once it develops cracks, the seal is compromised and transmission fluid can leak out. Before you actually replace the gasket, ensure that the bolts are all tight, since loose fittings can be the reason for the leak. This is a more challenging do-it-yourself repair, and unless you are very familiar with a a car’s engine, it is a best left to a certified mechanic
Cracked or fractured transmission oil pan
If you have recently done some unexpected off-roading or gone over a curb or two, you may have cracked the transmission oil pan. You can check this by getting under your car, looking for evidence of fluid, and seeing if it is leaking from the pan. A visual check should tell you whether or not this is your problem. This repair like the transmission fluid pan gasket repair is challenging for DIY and may be best left to the professionals.
Check your dipstick
It seems simple, but if you have recently checked your transmission, it is possible you did not engage the dipstick all the way in. With the movement of your car, it may have come out further and is now leaking transmission fluid. The fix is simple—just push it all the way back in.
Ensure that it is actually leaking transmission fluid
A common mistake when checking transmission fluid levels is that people check them when the engine is cold. It is necessary to let your vehicle warm up before checking the fluid level. The fluid need to expand up into the engine to be read properly. If you read it before the engine is warm enough, it will often read low when it is just fine.
For more information that is specific to your vehicle, Haynes® has a manual for almost every vehicle. A transmission leak is not something you want to wait to get looked at. Transmission fluid is deadly to animals and bad for the environment. It is important to get it fixed as soon as possible, not only for the good of your car, but for the good of your planet.