PSS Shaft Seal – Shaft seal
Photo: Mustad Marine, Public domain (Public Domain Mark 1.0), via Flickr (cropped)

PSS · Shaft seal

PSS Shaft Seal

The PSS (Packless Sealing System) is a dripless face seal that replaces the stuffing box on a propeller shaft: a carbon stator on a rubber bellows clamped to the stern tube runs against a stainless rotor held on the shaft by set screws, and the compressed bellows keeps the two faces together. Type A is the standard version for 3/4″–3-3/4″ (20–95 mm) shafts on sail and power boats, as High-Speed with hose barb (02-…) or Low-Speed without barb for boats that never exceed 10 knots (01-…); the PRO (03-…) adds a reinforced silicone bellows, 316 stainless clamps and a shaft retention collar. Metric shafts are M sizes within Type A and PRO, while Type B is the heavy seal for commercial shafts from 4″ to 6-1/2″. First made by PYI Inc., the seal is now made and sold by PSS Seal LLC under the same part numbers: 02-100-112 is a Type A for a 1″ shaft in a 1-1/2″–1-5/8″ stern tube, and its maintenance kit is 07-100-112R.

Manuals & documents

The links go to PSS’s own documents — some as archived copies of pages the maker has since taken down. We host no manuals or drawings.

Wear parts & part numbers

PartOEM numberAlso fitsNote
Propeller shaft seal02-078-112 · 07-078-112R1,2,3,4,5—Type A for 7/8″ shafts. Seal (02-…) and maintenance kit (07-…R) by stern tube OD: …-112 = 1-1/2″–1-5/8″. The kit holds the bellows, 2 O-rings, 5 set screws, 4 hose clamps with jackets, thread lock and an Allen key.
Propeller shaft seal02-100-112 · 02-100-134 · 02-100-200 · 07-100-112R · 07-100-134R · 07-100-200R1,2,3,4,5,6,7,8,9,10—Type A for 1″ shafts. Seal (02-…) and maintenance kit (07-…R) by stern tube OD: …-112 = 1-1/2″–1-5/8″, …-134 = 1-3/4″–1-7/8″, …-200 = 2″–2-1/8″.
Propeller shaft seal02-118-112 · 02-118-134 · 07-118-112R · 07-118-134R1,2,3,4,5—Type A for 1-1/8″ shafts. Seal (02-…) and maintenance kit (07-…R) by stern tube OD: …-112 = 1-1/2″–1-5/8″, …-134 = 1-3/4″–1-7/8″.
Propeller shaft seal02-114-200 · 02-114-214 · 07-114-200R · 07-114-214R1,2,3,4,5—Type A for 1-1/4″ shafts. Seal (02-…) and maintenance kit (07-…R) by stern tube OD: …-200 = 2″–2-1/8″, …-214 = 2-1/4″–2-3/8″.
Propeller shaft seal02-25M-112 · 02-25M-134 · 07-25M-112R · 07-25M-134R1,2,3,4,5,11—Type A for 25 mm shafts. Seal (02-…) and maintenance kit (07-…R) by stern tube OD: …-112 = 1-1/2″–1-5/8″, …-134 = 1-3/4″–1-7/8″.
Propeller shaft seal02-30M-134 · 07-30M-134R1,2,3,4,5—Type A for 30 mm shafts. Seal (02-…) and maintenance kit (07-…R) by stern tube OD: …-134 = 1-3/4″–1-7/8″.
Propeller shaft seal02-35M-200 · 07-35M-200R1,2,3,4,5—Type A for 35 mm shafts. Seal (02-…) and maintenance kit (07-…R) by stern tube OD: …-200 = 2″–2-1/8″.
Propeller shaft seal03-100-112 · 07-100-112PR · 03-25M-112 · 07-25M-112PR12,13,3,14,15—PRO for a 1-1/2″–1-5/8″ stern tube: 1″ shaft 03-100-112 with kit 07-100-112PR, 25 mm shaft 03-25M-112 with kit 07-25M-112PR. Other sizes use the Type A size codes with prefix 03 and kit suffix PR. Kit: silicone bellows, 2 O-rings, 5 set screws, 4 hose clamps in 316 stainless, thread lock, Allen key.
Propeller shaft seal01-100-11216,17,18—Type A Low-Speed without hose barb, 1″ shaft, stern tube 1-1/2″–1-5/8″. Only for boats that never exceed 10 knots and have no bearing in the stern tube; prefix 01, the rest as on the High-Speed seal.
O-ring07-N07-8 · 07-N10-0 · 07-N11-8 · 07-N30-M · 07-N11-4 · 07-N13-819,3,20—Rotor O-ring kit for Type A and PRO (2 O-rings, 5 set screws, Allen key, thread lock, 4 clamp jackets), by shaft: 07-N07-8 = 7/8″ and 22 mm, 07-N10-0 = 1″ and 25 mm, 07-N11-8 = 1-1/8″ and 28 mm, 07-N30-M = 30 mm, 07-N11-4 = 1-1/4″ and 32 mm, 07-N13-8 = 1-3/8″ and 35 mm. For when the rotor has been moved or removed but the bellows stays.
Fastening kit07-014KIT · 07-038KIT3,21—Set screw kit (6 cup-point set screws, Allen key, thread lock): 07-014KIT for 3/4″–1-3/8″ (20–35 mm) shafts, 07-038KIT for 1-1/2″–3-3/4″ (38–95 mm).
Installation kit07-KIT-012 · 07-KIT-034 · 07-KIT-100 · 07-KIT-114 · 07-KIT-11222,3,23—T-kit for the water feed (T-piece, 6 ft of 3/8″ hose, clamps), chosen by the inside diameter of the engine’s raw-water hose it tees into: 07-KIT-012 = 1/2″, 07-KIT-034 = 3/4″, 07-KIT-100 = 1″, 07-KIT-114 = 1-1/4″, 07-KIT-112 = 1-1/2″. Needed above 12 knots; measure the hose before ordering.
Vent valve07-HYV-ENTKIT24,3,25—Hy-Vent float vent (made by Taco) with 3/8″ barb and 2 clamps, for the top end of the vent hose on vented seals: lets air out and closes against water.
Hose barb plug07-141-8NPSMPLUG26—Screws into the carbon stator in place of the hose barb on boats that never exceed 10 knots; the seal then has to be burped by hand.
Hose07-TFV-038FT · 07-TFV-0382503,27—Blue silicone hose, 3/8″ ID, for the vent line or water feed on the hose barb of every Type A and PRO: 07-TFV-038FT by the foot, 07-TFV-038250 as a 250 ft roll.

Numbers checked against the sources below on 12 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

TaskInterval
Shaft seal (stuffing box)At least every 6 months: check the bellows for cracks, splits, tears and brittleness; replace at the first sign of deterioration28
Full serviceMaintenance kit (bellows, O-rings, set screws, clamps): Type A at least every 6 years whatever its condition (07-…R); PRO every 8–10 years (07-…PR)2,13,17,28
Hoses & clampsBellows clamps: replace at any sign of corrosion and with every bellows change28
GasketsWhenever the rotor is loosened or moved: new set screws (single-use cup points); whenever it is moved or removed: new rotor O-rings (O-ring kit)17,19
First serviceRun-in of about 1 hour: a fine mist and black carbon dust are normal during this time17,28
Storage / winterisingLaid up afloat for about 3 months or more: briefly pull the carbon back so a little water gets between the faces28
Season checkAfter launching, and whenever air may be trapped in a seal without vent line or water feed: burp it by pulling the carbon back off the rotor until a short spray of water comes out26

From the PSS Type A & PRO installation instructions (2025 edition), the maker’s FAQ and its maintenance-kit pages. Type B (shafts from 4″) has its own instructions: new bellows at least every 8 years.

Specifications

VersionsType A High-Speed with hose barb (02-…); Type A Low-Speed without barb, max. 10 kn (01-…); PRO with reinforced silicone bellows, 316 clamps and shaft retention collar (03-…); Type B for commercial shafts 4″–6-1/2″; maintenance kits 07-…R (Type A) and 07-…PR (PRO)29,1,12,30,16,3
SizesType A and PRO: shafts 3/4″–3-3/4″ (20–95 mm), stern tube OD 1-1/4″–7-1/8″. Shaft code: 078 = 7/8″, 100 = 1″, 118 = 1-1/8″, 114 = 1-1/4″, 138 = 1-3/8″, 112 = 1-1/2″, 25M = 25 mm; tube code: 114 = 1-1/4″–1-3/8″, 112 = 1-1/2″–1-5/8″, 134 = 1-3/4″–1-7/8″, 200 = 2″–2-1/8″, 214 = 2-1/4″–2-3/8″, 212 = 2-1/2″–2-5/8″ (inch codes on metric shafts too). Type B: 4″–6-1/2″ (100–150 mm)1,12,30,3
Max. shaft speed10000 rpm (Type A and PRO); Type B 7000 rpm1,12,30
Operating temperatureType A −15 to 107 °C (5 to 225 °F); PRO and Type B −25 to 220 °C (−13 to 425 °F)1,12,30
Venting / water feedUp to 12 kn under power with no bearing in the stern tube: vent hose 3/8″ (8–9 mm) ID, top end at least 0.6 m (2 ft) above the waterline near the centreline, no loop. Faster, with a stern-tube bearing or if the tube can run dry: raw-water feed at max. 10 psi (0.68 bar); twins that exceed 12 kn on one engine need a crossover line between the seals28,17,1
Bellows compressionMeasured from where the rotor just touches the carbon: Type A 3/4″ (20 mm) on 3/4″–1-3/8″ shafts, 1″ (25 mm) on 1-1/2″–3-3/4″; PRO 3/4″ (20 mm) up to 2-1/2″ (65 mm) shafts, 1″ (25 mm) on 2-3/4″–3-3/4″31,28
Tightening torquesRotor set screws approx. 8 Nm (6 ft-lb) on 3/4″–1-3/8″ shafts, approx. 11 Nm (8 ft-lb) on 1-1/2″–3-3/4″; medium-strength (blue) thread lock; 2 holes at 90°, each with a gripping and a locking screw28
MaterialRotor 316L stainless; stator resin-impregnated carbon-graphite; bellows nitrile (Type A) or silicone with polyester/aramid plies (PRO); rotor sealed on the shaft by 2 nitrile O-rings1,12
Dimensions02-100-112: bellows 6.875″ long uncompressed, rotor OD 2.375″; 02-114-200: bellows 7.375″, rotor OD 2.875″; PRO for 1″ shafts: 7.8″ uncompressed, approx. 7.05″ compressed1,12
Warranty3 years from first use or shipment, for the original buyer31,28

Good to know

  • Order by two measurements: the shaft diameter and the outside diameter of the stern tube. Both are coded in the part number, and the stern tube code is in inches even on metric shafts.3
  • The rotor set screws are single-use cup points, two per hole: one grips the shaft, the second locks it. Keep a set screw kit aboard; without spares, swap the two screws in each hole so an unused cup bites the shaft.13
  • Slide the rotor on with soapy water only: no oil, grease or silicone spray on the O-rings or bellows. Keep fuel, oil and similar products out of the bilge around the seal.28
  • Before tightening, mark the neutral point where the rotor just touches the carbon, then push it on by the specified compression. If the seal still sprays a mist underway after the run-in, it usually needs another 1/8″–1/4″ of compression.17
  • A high-pitched squeal means the faces are running dry: check the vent or water-feed line, and let the faces cool down before you touch them.28
  • Before uncoupling the shaft or removing the gearbox afloat, clamp the shaft so the bellows stays compressed; otherwise the faces separate and water comes in.28

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Sources

  1. shaftseal.com/marine/pss-type-a-seal.html
  2. shaftseal.com/marine/pss-maintenance-kit.html
  3. shaftseal.com/downloads/pss-shaft-seal-price-list.pdf
  4. pssseal.store/products/pss-type-a-shaft-seal-high-speed
  5. pssseal.store/products/pss-type-a-maintenance-kit
  6. citimarinestore.com/en/pyi-pss-type-a-shaft-seals-inches/316-02-100-112.html
  7. citimarinestore.com/en/pyi-pss-type-a-shaft-seals-inches/318-shaft-diameter-1-stern-tube-…
  8. cwrdistribution.com/product/50827/pss-shaft-seal-1-shaft-1-tube
  9. citimarinestore.com/en/pyi-type-a-pss-shaft-seal-maintenance-kits/6565-07-100-112r-shaft-…
  10. cwrdistribution.com/product/51294/pss-shaft-seal-maintenance-kit-1-shaft-1-1-2-tube
  11. citimarinestore.com/en/pyi-pss-type-a-shaft-seals-metric/5181-02-25m-112.html
  12. shaftseal.com/marine/pss-pro-shaft-seal.html
  13. shaftseal.com/marine/pss-pro-maintenance-kit.html
  14. pssseal.store/products/pss-pro-shaft-seal
  15. pssseal.store/products/pss-pro-maintenance-kit
  16. pssseal.store/products/pss-type-a-shaft-seal-low-speed
  17. shaftseal.com/marine/pss-faq.html
  18. pssseal.store/products/low-speed-carbon-stator
  19. shaftseal.com/marine/pss-o-ring-kits.html
  20. pssseal.store/products/o-ring-kit
  21. pssseal.store/products/pss-set-screw-kit
  22. shaftseal.com/marine/pss-t-kits.html
  23. pssseal.store/products/t-kit
  24. shaftseal.com/marine/hy-vent.html
  25. pssseal.store/products/hy-vent
  26. pssseal.store/products/pss-hose-barb-plug
  27. pssseal.store/products/3-8-i-d-silicone-hose
  28. shaftseal.com/downloads/pss-type-a-pro-seal-instructions.pdf
  29. shaftseal.com/marine/pss-shaft-seals.html
  30. shaftseal.com/marine/pss-type-b-seal.html
  31. shaftseal.com/marine/pss-installation-instructions.html

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