Overfilling transmission fluid can cause several problems that can damage your vehicles transmission system. Here are some of the symptoms of an overfilled transmission:

• Foamy fluid: If there is too much fluid, the transmission fluid will become foamy. This can lead to poor shifting, high internal temperatures, seal failure, and part pitting.

• Blown seals: Automatic transmission fluid expands a lot more than engine oil, and overfilling can cause the fluid to blow the seals, like where the torque converter rides. This can affect your output shaft seals and lead to slippage, excessive wear, and improper shifting.

• Whipped fluid: Overfilling can cause the fluid in the pan to be whipped into foam by contact with the rotating parts. This can compress the bubbles and cause problems when the pressurized fluid tries to actuate the various components, similar to air in the brake lines.

If you discover that you have overfilled your transmission, it is important to remove the excess fluid as soon as possible. You can do this by using a fluid pump or siphon to remove the excess fluid through the dipstick tube. It is important to remove the excess fluid carefully to avoid removing too much fluid and causing the opposite problem of underfilling the transmission.