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Q: Why is my transmission fluid leaking?

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Recently my car has been losing transmission fluid. The leak is not external since there is never a puddle underneath the car from the pan, the back, or by the motor. My question is, where all can I check for external leaks before i force myself to drop the transmission or take it to a shop. The fluid is brown but not burnt smelling but it's losing half a quart of fluid a week. I would really appreciate some help.

My car has 139000 miles.
My car has an automatic transmission.

Generally, there are only a few places for leaking transmission fluid to go to since it does not burn off inside the transmission, unlike motor oil inside an engine. You have already ruled out the possibility of an external leak somewhere because of the lack of any visible signs of leaking.

A ruptured modulator can allow the fluid to be sucked into the engine (this is uncommon), or the fluid may have leaked into the transmission cooler. Another possibility may be a leak that is only active when the vehicle is in use or during times where hydraulic pressure is present in the transmission, such as while driving.

Try looking underneath the car and clean the surface areas under the transmission with a brake cleaner to get rid of any grease or oil spots. After cleaning, take the car for a drive. When you return, look underneath the car to see if you can spot any visible signs of fresh fluid leaking from under the transmission.

It is recommended that you get a certified technician, such as one from YourMechanic, to come to your location and determine the cause of the transmission leak.

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