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Shaft Seal Maintenance - Step 5

Maintaining Dripless Shaft Seals

Story and photography by Capt. Vincent Daniello

Shaft Seal Maintenance - Step 5

Now replace both O-rings inside the bore of the rotor, lubricate them with dish soap—never grease—and slide it back onto the shaft until it touches the carbon seal. Mark this neutral position with tape or a Sharpie and then push the rotor farther against the springiness of the bellows—for shafts smaller than 1½ inches, an extra three quarters of an inch typically develops the right pressure. Larger shafts or troublesome seals require a bit more.

The two holes in the rotor call for four setscrews—two against the shaft and two to lock the bottom screws in place. Don’t reuse a setscrew. Once the sharp circular edge at the tip is flattened, it won’t properly bite. (In a pinch though, you can check all four setscrews. The two locking setscrews may be sharp enough to work.) Use thread lock, too.

And don’t forget, if your dripless shaft seal continues to be troublesome, a bent shaft or a misaligned engine may be to blame. If your seal dances up and down at cruising speed, you’ve got an alignment issue.
Worn engine mounts, on the other hand, may shake the shaft
only in rough seas.

In any case though, it’s a good idea to correct anything more than an occasional drip while underway. Neither lip nor face seals should drip at the dock.