Dealing With a Leaking Automatic Transmission
When you have an automatic transmission that is leaking, it can be challenging to find the leak and stop it. Often, the fluid leaking from the system is blown back under the vehicle when it moves, so it spreads out the fluid on the undercarriage and other parts of the car. You may need to take the vehicle to a transmission repair shop to find the leak and fix it, but there are some places you can look before you do.
Oil Pan Gasket
The transmission oil pan is located on the bottom of the transmission housing, and there is a gasket that creates the seal between the pan and the transmission case. Most of these oil pans use twenty or more bolts to secure the pan to the case, and if a bolt gets loose enough, the seal in the area can start to break, allowing oil to seep out.
When one bolt is missing, the leak is typically a small amount that leaves a few drops of transmission oil on the ground under your car, but if several of the bolts are loose or missing, the leak can be enough to be very noticeable. The oil level will drop enough over time that the transmission will not shift properly, and you may start to see some drivability issues.
Typically, missing bolts have fallen out because they were not tight enough, or they can be sheared off if the transmission is impacted by an obstacle under the car or debris on the road. If the bolts are sheared off, you need to take the vehicle to a transmission repair shop so they can drill out the remains of the bolts and replace them.
Cooling Line Leaks
Automatic transmissions have two cooling lines that run from the side of the transmission to the radiator in the car or an oil cooler installed behind the radiator. These lines are steel, preformed lines that run alongside the vehicle's frame, but they can develop leaks over time. Often the leaks develop at the fittings and you may be able to tighten them, but if the fittings are worn enough, the best solution is to replace the lines and fittings as a unit.
Take the car into a transmission repair shop and have the tech replace the lines if you have that option. The lines are difficult to reach on some vehicles, so putting the car on a lift will make the job easier, and the tech will have the right wrenches for the fittings, making the job easier.
While many other areas can leak as well, most of them are not something the average driver will be able to access and repair at home.