* Transmission Pan Gasket: This is the most common cause. The pan gasket seals the bottom of the transmission. If it's old, cracked, or improperly installed, it can leak, especially when the fluid is sitting and not under pressure. Leaks often appear near the bottom left (or right) side of the pan.
* Side Cover Gasket (if applicable): Some transmissions have side covers, particularly for access to the valve body or other internal components. A leak from a poorly sealed side cover gasket could be observed on the left side. This is less likely than a pan gasket leak.
* Seal on the output shaft: The output shaft connects the transmission to the transfer case. A worn or damaged seal on this shaft (on the left side of the transmission) could leak when the vehicle is not running. Fluid might seep out over time even without pressure.
* Transmission Case Crack (less likely): While less probable, a crack in the transmission case itself (though less likely on the side rather than the bottom) could cause a leak. This is a more serious issue requiring repair or replacement of the transmission.
* Improperly installed components: During past maintenance (transmission service, etc.), a component might have been reinstalled improperly, leading to a leak.
Troubleshooting Steps:
1. Clean the area thoroughly: Before trying to pinpoint the leak, clean the transmission and surrounding area with degreaser and a pressure washer (if possible). This helps you pinpoint the precise location of the leak. Let it dry completely.
2. Inspect closely: Once dry, carefully examine the transmission case, pan, and all connections on the left side. Look for any wet spots or glistening fluid.
3. Check the fluid level: Check the transmission fluid level when the engine is cold. A low fluid level exacerbates leaks by increasing the likelihood of seals failing.
4. Run the engine (carefully): With the transmission in Park, start the engine and run it for a short time (monitoring carefully for other issues). Watch for any fresh leaks appearing.
5. Consult a mechanic: If you cannot locate the leak or are uncomfortable working on the transmission yourself, it's best to take the Jeep to a qualified mechanic. They have the experience and tools to properly diagnose and repair the leak.
Given the age of the vehicle, a failing pan gasket is the most likely suspect. But a proper diagnosis is essential before you start replacing parts. Ignoring a transmission leak can lead to significant transmission damage due to low fluid levels.
