* Incorrect installation: The most likely culprit. Even a new transmission can leak if not installed properly. This could involve:
* Improper gasket seating: The transmission gasket may not be properly seated or may be damaged during installation.
* Loose or damaged bolts: Transmission bolts might be loose or stripped, leading to leaks.
* Damaged transmission case: Although less likely with a new transmission, the case could have been damaged during shipping or installation.
* Incorrect torque specifications: Using the wrong torque on bolts can cause leaks.
* Damaged or improperly installed drain plug: The drain plug on the transmission itself (or even the torque converter) might be loose, damaged, or improperly tightened.
* Damaged pan gasket (if applicable): Some transmissions use a separate pan gasket. This could be damaged or improperly installed.
* Other seals: Even with a new transmission, other seals in the surrounding area, such as the input shaft seal, output shaft seal, or bellhousing seals, could be leaking. These are often original seals that weren't replaced during the transmission swap.
* Fluid cooler lines: The transmission fluid cooler lines (if the car has one) are external to the transmission itself and could be leaking. These lines are often overlooked during a transmission replacement.
What to do:
1. Return to the installer: If the work was done by a shop, take it back immediately. This is the most crucial step. They should diagnose and fix the problem under warranty (or at least investigate it at no additional cost to you).
2. Thorough inspection: You or a mechanic need to carefully inspect the entire transmission and surrounding areas for the source of the leak. This often involves cleaning the area thoroughly, then running the engine and carefully observing where the fluid is coming from. Pay attention to every seal, gasket, and connection.
3. Check the fluid level: Before assuming it's a leak, check the transmission fluid level. Sometimes an overfill can appear as a leak if the excess fluid is weeping out.
Unless you have significant mechanical experience, do not attempt major repairs yourself. Improperly fixing a transmission leak can cause further, more costly damage.
