* Damaged transmission seal: The most likely culprit. During CV axle removal and installation, the inner CV joint seal on the transmission could have been damaged. This is particularly true if improper tools were used, excessive force was applied, or the seal wasn't properly seated during reassembly.
* Loose or damaged transmission drain plug: While less likely, it's possible the drain plug was loosened or damaged during the axle job, resulting in a leak.
* Damaged transmission case: Highly unlikely, but if excessive force was used during the axle removal/installation, it's remotely possible the transmission case itself was cracked or otherwise damaged. This is usually accompanied by other significant damage.
* Existing leak masked by old grease: The leak might have already been present, but the old grease from the CV axle boot masked it. The new axle replacement might have disturbed the grease, revealing the pre-existing leak.
To diagnose the leak:
1. Locate the leak: Pinpoint the exact location of the leak. Is it coming from around the inner CV joint seal, the drain plug, or elsewhere on the transmission?
2. Clean the area: Thoroughly clean the transmission area to remove any old grease or oil. This will allow you to easily see where the leak is originating.
3. Observe: After cleaning, run the car for a short time and observe where the leak reappears.
4. Inspect the seals and plug: Once the leak is located, carefully inspect the relevant parts, paying close attention to the inner CV joint seal and drain plug.
If you're not comfortable performing this diagnosis yourself, take the vehicle back to the mechanic who replaced the CV axles. They should be responsible for rectifying any damage they may have caused during the repair. A leaking transmission is a serious problem that needs to be addressed promptly to prevent further damage.
