* Incorrect Installation: The most common reason. The seal needs to be seated perfectly, and if it's even slightly misaligned or not fully seated, it will leak and eventually pop out. This includes ensuring the transmission and housing surfaces are clean, free of debris, and properly lubricated (usually with transmission fluid). The seal may also be damaged during installation if improper tools are used.
* Damaged Transmission Output Shaft: A worn, scored, or bent output shaft won't provide a proper seating surface for the seal, causing it to pop out. This is a significant issue requiring repair or replacement of the shaft.
* Damaged Transmission Case: Similar to the output shaft, a damaged or worn transmission case (where the seal sits) will prevent a proper seal. This often involves cracks or significant wear in the bore where the seal fits.
* Excessive Pressure: While less common, extremely high transmission fluid pressure could force the seal out. This might indicate a problem within the transmission itself (e.g., a blockage or internal failure).
* Incorrect Seal: Although you've replaced it twice, it's possible the wrong type of seal was used. Double-check the part number and ensure it's the correct seal for your specific transmission.
* Improper Torque on the Retaining Nut/Ring: The seal may be held in place by a nut or retaining ring. If this isn't tightened to the manufacturer's specification, the seal will be loose and prone to popping out.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine the transmission output shaft and the case bore where the seal sits. Look for any damage, scoring, or wear.
2. Measure the Shaft and Bore: Use a micrometer to accurately measure the shaft diameter and the bore diameter. This ensures the seal is the correct size. Any significant deviation from specs points to a damaged part.
3. Check for Debris: Make absolutely sure the mating surfaces are completely clean and free of any dirt, metal shavings, or old sealant.
4. Use the Correct Sealant (if needed): Some seals require a compatible sealant to aid in installation and sealing. Don't use too much.
5. Professional Assistance: If you're not comfortable with these steps, taking it to a qualified transmission specialist is highly recommended. They have the experience and tools to diagnose the problem correctly.
The fact that it's happened twice strongly indicates an underlying mechanical problem, not just a faulty seal. Addressing the root cause is crucial to prevent this from happening again. Ignoring it could lead to significant transmission damage.
