Maintaining Dripless Shaft Seals
Story and photography by Capt. Vincent Daniello
The stainless steel rotor on face seals like PYI’s Packless Shaft Seal (www.pyiinc.com) rotates with the shaft. It’s simply pressed against a stationary ultra-smooth carbon surface by the bellows that attaches to your shaft log. If either the carbon face or stainless rotor loses its polish, your seal will leak, and once leaking, the steady drip of seawater will leave residue behind, worsening the leak. Technically, the surfaces should self-polish with use. If they don’t, fold a sheet of 600-grit wet sandpaper in half, slip it between the carbon and stainless faces, and pull the sandpaper around the circumference of the shaft a few times.
Worst case, you may have to lap a badly neglected stainless-steel rotor. With the boat out of the water, remove the shaft from the transmission coupling (you may have to remove the prop as well in order to slide the shaft far enough astern to get adequate clearance), slide the rotor off, and work it in a figure-eight motion on 600-grit sandpaper—a piece of glass ensures that sandpaper lays perfectly flat. If you must also lap the carbon seal, go easy; it’s much softer than stainless.