How to Replace Mercury Tracker 25EL Prop Shaft Seals

Leaking oil seals at the prop shaft means oil is escaping from your Mercury outboard’s lower unit, and is also a sign that water is getting into it. 

Water in the gearcase causes extreme damage, so replacing those leaking oil seals is an absolute priority. Watch the video above and follow the steps below to replace the prop shaft oil seals on a Mercury Tracker 25EL or any similar outboard motor. 

Tools and Parts Needed – Mercury Tracker 25 Output Seal Replacement

Tools

  • Ratchet and 5/16th socket
  • Carrier tool
  • 19mm, 22mm impact sockets
  • Hammer
  • Torque wrench

Mercury Tracker 25 EL prop shaft seals replacement

Replacing Mercury Tracker 25EL Prop Shaft Seals

Step 1. Remove the propeller, and clean out the prop shaft housing with contact/brake cleaner.

Step 2. Remove the three 5/16th inch bolts securing the retaining plate and O-ring, followed by the retaining plate and O-ring.

Mercury Tracker outboard output shaft seals replace

Step 3. Use a Mercury carrier tool to remove the bearing carrier assembly. 

NOTE: The assembly has a reverse thread, so turn it clockwise to remove it.

Step 4. Remove the prop shaft and the reverse gear from the bearing carrier assembly, and secure the assembly in a vice.

Mercury Tracker 25 prop shaft seals replacement

Step 5. Remove the inner and outer oil seals from the bearing carrier assembly.

Step 6. Apply a small amount of red threadlocker to the outside of the new oil seals.

Step 7. Install the inner oil seal into the bearing carrier assembly. Use a 19mm impact socket to drive the seal 1/8th of an inch beyond the lower lip inside the assembly.

Mercury Tracker engine prop shaft seals replacement

Step 8. Install the outer oil seal into the bearing carrier assembly. Use a 22mm impact socket to drive the seal 1/8th of an inch beyond the upper lip inside the assembly.

Mercury Tracker outboard prop shaft seals replacement

Step 9. Pack the inside of the bearing carrier assembly between the oil seals with marine grease.

Step 10. Reinstall the prop shaft into the prop shaft housing.

Step 11. Reinstall the reverse gear into the bearing carrier assembly, then reinstall the assembly into the prop shaft housing.

Mercury Tracker 25 bearing carrier assembly

Step 12. Use a Mercury carrier tool to torque the bearing carrier assembly to 80 foot-pounds. 

NOTE: The assembly has a reverse thread, so turn it counterclockwise to tighten it.

Step 13. Lightly grease the new O-ring, and install it into the prop shaft housing.

Step 14. Reinstall the retaining plate and the three 5/16th bolts.

Mercury Tracker 25EL output shaft replacement

Step 15. Reinstall the propeller and you’re done.

SEAL KIT
Mercury

SEAL KIT

Qty.
LUBE-2 4 C @12
Mercury

LUBE-2 4 C @12

Qty.

 

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