How to Replace Mercury Tracker 25EL Input Shaft Seals

When driveshaft (or input shaft) seals start to leak, you’ll need to replace them before the gearcase suffers major damage. 

Water getting into the gearcase, or oil escaping from it can be catastrophic, so replacing worn seals is essential to the health of your outboard. Watch the video above and follow the steps below to replace the driveshaft seals in a Mercury Tracker 25 outboard.

Tools and Parts Needed – Mercury Tracker 25 Input Shaft Seal Replacement

Tools

  • Ratchet and extensions
  • 14mm, 18mm sockets
  • Locking pliers
  • Flathead screwdriver
  • Hammer
  • Torque wrench

Parts

Mercury Tracker 25 input shaft seals replacement

How to Access Mercury Tracker 25 Driveshaft Seals

To access the driveshaft seals, you’ll have to remove the gearcase/lower unit, the water pump, and the propeller shaft and bearing carrier assembly. Use the videos featured below for reference. 

Lower unit removal: 

Water pump removal:

Prop shaft and bearing carrier removal:

How to Replace Mercury Tracker 25 Driveshaft Seals

Step 1. Hold the driveshaft steady with locking pliers. 

Mercury Tracker 25 driveshaft

PRO TIP: Use shop towels or rags to prevent the pliers from damaging the driveshaft.

Step 2. Remove the 14mm bolt within the gear housing that secures the bottom of the driveshaft.

Mercury Tracker driveshaft parts diagram

Step 3. Lift the driveshaft to release the pinion gear and the bearing from the lower end of the driveshaft and retrieve them from within the gear housing.

Step 4. Lift the driveshaft and remove it from the lower unit.

Mercury Tracker 25 lower unit driveshaft

Step 5. Pry out the old oil seals from the sleeve in the top of the lower unit using a flathead screwdriver. Be careful not to scratch the sleeve.

Mercury Tracker 25 input shaft seal replacement

Step 6. Apply blue threadlocker to the new seals, and install them back-to-back with the lower seal facing downward and the upper seal facing upward. Use an 18mm socket to press each of the new seals into place by gently tapping the socket down on the seals with a hammer.

Step 7. Pack the voids between the seals with PTFE marine grease.

Mercury 25 Tracker input shaft seals

Step 8. Reinstall the driveshaft into the lower unit.

Step 9. Reinstall the bearing and the pinion gear onto the bottom of the driveshaft, followed by the 14mm bolt.

Mercury Tracker 25 input shaft parts diagram

Step 10. Hold the driveshaft steady with locking pliers, and torque the bolt to 13 foot-pounds.

PRO TIP: Use shop towels or rags to prevent the pliers from damaging the driveshaft.

SEAL KIT
Mercury

SEAL KIT

Qty.
LUBE-2 4 C @12
Mercury

LUBE-2 4 C @12

Qty.

 

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