Q: Transmission selector shaft seal leakage. Does it need to be fixed and how expensive is the repair?

Hi and thanks for your question. The transmission gear selector shaft is leaking from the rubber grommet is probably hard or torn. Your transmission should be an AODE Ford transmission.

First, put wheel chocks around the vehicles tires to keep the vehicle from moving and put the transmission in neutral then back into park. This will release any tension on the shift selector. Drain the oil from the transmission and remove the oil pan.

On the shift selector, you will see a nut. (before doing anything, take note and a picture or draw the image of the shift selector hooked up to the main valve in the transmission). Remove the nut and the selector will come out of the transmission housing. Remove the rubber grommet that seals the shaft to the transmission housing. Install the new rubber grommet and install the selector.

Put the nut back on the selector and tighten it up. Rotate the shift selector to ensure that all of the gear selections will work. Put on a new oil filter to the transmission and a new oil pan gasket. Put on the oil pan to the transmission and install the bolts.

Torque the bolts to 8 foot pound in a star pattern across the pan. Then re-torque the bolts to 10 foot pounds with the same pattern. Put in the transmission oil, remove the wheel chocks, and take the vehicle on a road test. Recheck for any leaks.

If you need further assistance with your leak, then seek out a professional, preferably a professional from YourMechanic who can come to your home and help you with your vehicle.