PSS Shaft Seal Maintenance

(extracted from Waypoints Issue 7 and the PSS website)

The PSS Shaft Seal Packless Sealing System is an almost maintenance-free dripless stuffing box and packing gland replacement for sailboat and power boat drivetrains. The PSS Shaft Seal is a mechanical seal that uses a self-aligning carbon-graphite stator to ensure a 100% watertight seal with proven reliability. This seal will eliminate shaft wear and minimize corrosion. The PSS shaft seal should not leak or drip at all when the boat is at rest. However, while running during the break-in period, you may see some fine spray with black carbon in it. The carbon comes off the fixed carbon seal that is attached to the bellows as it seats itself against the rotating shaft collar. Misting should disappear after approximately one hour of operation. If it continues an additional ).25" of compression should be applied. If it continues, contact your dealer for resolution.

If you hear a highpitched squeal during operation you should check the water supply to the seal. Use caution as the seal may be hot. However, the grounding brush on the propeller shaft will also make a squealing noise at times so remember to check it too. Now if your shaft seal is dripping at rest, some foreign material is on the face of the seal between the SS rotor and the carbon flange. To correct this pull back on the bellows and carbon flange (do not touch the flange or rotor faces) and work a rag in between the flanges. Then pull it around the shaft between the flanges. This will allow water to flush the foreign materials from between the sealing surfaces. Remember water will enter the boat when you are performing this process. Remove the rag and the leaking should stop. You may be wondering why I said not to touch the faces. Oil will cause the seal to leak - even the natural oil on your fingers.

If you think or know that the SS rotor has moved up on the shaft you will need to check the amount of compression in the bellows. The bellows should have 1" of compression in it for a 1.25 - 2" shaft (1.25" compression for a 2.25 - 3.75" shaft). It's probably a good idea to check the compression every few years.

The only way to test this is to remove the locking setscrews and loosen the setscrews in the SS rotor and slide it up the shaft toward the shaft coupling until the bellows is relaxed. This can be accomplished when the boat is in the water but be sure to have safe guards in place to keep incoming water under control. Slide the SS rotor up to the bellows, mark the shaft with a pencil or tape, and slide the rotor the required compression distance towards the bellows and tighten the setscrews to 6-8 ft.-lbs Replace the locking set screws and tighten. You can add some type of clamp to ensure the rotor does not move back up the shaft such as a split shaft zinc.

The bellows should be inspected at least every six months and replacement is recommended every six years by PYI - an out of the water job. See the PYI website for replacement kits.

If your boat has sat for three months or more you should flush the seal while the boat is in the water before engine start-up for the first ime by pushing the bellows away from the rotor to allow a small quantity of water to enter.

For more info. about PSS shaft seals contact PYI Inc. at www.pyiinc.com