PYI Inc | PSS Installation Guide (2023)

Important - read before you start!

Before beginning the installation, carefully read the following warnings and instructions. Failure to follow the warnings and instructions could result in personal injury or even death, or damage to property, the environment, or property.

The PSS (Packless Sealing System) shaft seal ("PSS") that you are about to install is a grommet that when properly installed and maintained protects against water entering the boat where the wave enters the hull. Before beginning the installation, ensure that you or your nominated installer are a qualified, knowledgeable and qualified professional to correctly install the PSS and that you have all necessary tools and additional equipment on hand before proceeding with the installation begin.

  • If the motor gearbox is removed for repair or the boat is launched without the gearbox installed, the shaft must be held in place with a fixture that secures the shaft to the PSS bellows in its normal "compressed mode".
  • ONLY install the PSS when the boat is out of the water.
  • DO NOT USEOil, grease (petroleum products) or silicone products at no time during installation. Use soap and water to lubricate the rotor o-rings as you slide it down the shaft.
  • Clean the sealing area of ​​your boat to avoid contaminating the sealing surface with dirt, oil, or other debris. Do not damage or scratch the surface of the carbon or the surface of the stainless steel rotor during unpacking or while handling or installing the PSS.
  • There should be a total of four (4) set screws in the two holes of the rotor (2 set screws in each hole). If you need to move the stainless steel rotor, be sure to remove the top setscrews to gain access to the bottom two setscrews.
  • Do not reuse the supplied tapered set screws. If the hollow point set screw has become flattened from repeated tightening, replace the affected screw with a new one.
  • There should be a total of four (4) hose clamps securing the boot ends. These clamps should be replaced when they show signs of corrosion.
  • Do not slide the rear bellows boot down too far over the stern tube. The leading edge of the stern tube could damage the inner ribs of the bellows and unduly restrict the movement and travel of the bellows.
  • When fitting a vent line (boats under 12 knots) do not loop the top of the hose as this could encourage a siphon.
  • If the boat is stored for a long period of time (generally 3 months or more), it is necessary to move the carbon disc backwards to allow a small amount of water to enter the boat.
  • Like any hose below the waterline, the PSS bellows needs to be inspected regularly (i.e. at least every 6 months in most circumstances) and checked for signs of wear (cracks, splits, fissures, brittleness or other signs). . If there are signs of wear, the bellows must be replaced. As preventative maintenance, the bellows should be replaced at least every 6 years for Type A seals and every 8 to 10 years for PSS PRO seals, regardless of its apparent condition.
  • Do not allow petroleum based liquids or corrosive materials to come into contact with the PSS. Make sure this doesn't happen, e.g. B. for general maintenance work or when storing the engine for the winter.
  • The stem should be nearly centered and parallel to the stem protocol.
  • Do not use an ozone generator (such as an air purifier) ​​on or near your boat. The additional ozone accelerates the deterioration of all rubber products, including PSS bellows.
  • In an environment where unsealed batteries emit sulfuric acid fumes, the bellows will need to be inspected and replaced more frequently. Sulfuric acid fumes accelerate the deterioration of all rubber materials, including PSS bellows.
  • Do not use sealant to attach the bellows to the stern tube or the hose to the hose barb.
  • Don't run dry.
  • Do not use the PSS SEAL on a submarine vehicle.
(Video) How To Compress A PSS Shaft Seal

component list

  • Stainless steel hose clamps - 4 pcs
  • Nitrile bellows(PRO Seal uses silicone bellows)- 1Menge
  • Carbon Graphite Flange - 1lot
  • Edelstahlrotor - 1qty
  • Stainless Steel Set Screws - 4 pcs(1 spare also included)
  • Nitrile O-Rings – 2 pcs(2 spare parts also included)
  • Stainless Steel Hose Barb Fitting - 1pc
  • Hose Barb Insert and Washers - 1 quantity
  • Clamp jackets - 4 pcs
  • Haltekragen - 1 meng(Pro Seals only)

The PSS shaft seal is a mechanical seal created between the flat surfaces of the rotating stainless steel rotor and the stationary carbon flange. The stationary carbon flange attaches to the ship's stern tube with hose clamps, and the carbon flange attaches to the front of the bellows with hose clamps. The stainless steel rotor sits on the shaft in front of the carbon flange. The stainless steel rotor is used to compress the bellows before the collar is secured to the shaft with set screws. This compression (preload) maintains contact between the surfaces and allows the PSS to compensate for the thrust of the propeller. The carbon flange is drilled larger than the shaft diameter, allowing it to "float" around the shaft, accommodating most misalignment and vibration problems. The stainless steel sleeve is sealed to the shaft by two O-rings that are embedded in the hole in the sleeve. These o-rings rotate with the shaft and stainless steel rotor and will not wear out during operation.

installation Guide

In any case, the boat must be out of the water for this installation.

  1. Unscrew the shaft coupling from the gearbox coupling.
  2. Remove the shaft coupling from the shaft. The coupling types vary depending on the manufacturer. For example, some couplings use set screws to hold the coupling in place, while others use a rolling pin and still others use a nut (always use the appropriate tools and procedures for your particular application).
  3. Remove the old stuffing box and packing material. There are three styles of gland packing found on most boats: Classic, Bolt-On and Threaded.
  4. Clean the entire exposed shaft with very fine sandpaper (#400 or #600 grit) to remove any dirt or rough edges. Pay special attention to the keyway on the front end of the shaft where the stainless steel rotor fits through. Shaft and keyway mustnothave no sharp edges that could damage the O-rings during installation.
  5. Slide the open end of the bellows and its hose clamps down the shaft and onto the bare stern tube, making sure the bellows is properly seated over the shaft block. Once the bellows is in place, it should overlap the stern tube by the same amount as the bellows boot to allow the hose clamps to properly tighten the bellows to the shaft block.WARNING: Do not slide the bellows boot too far down and over the stern tube.If the boot is pushed too far onto the stern tube, the leading edge of the stern tube may damage the inner ribs of the boot and unduly limit the boot's deflection. Instead, tighten the hose clamps to secure the bellows to the stern tube and fit the black clamp protector to the end of the hose clamps.
  6. Make sure the carbon flange is properly seated on the front end of the bellows and that the two hose clamps secure it properly. Also, confirm that the charcoal is free of any flaws or imperfections on its polished surface.
  7. Remove the stainless steel rotor from the protective cover. Make sure two (2) O-rings are placed in the O-ring grooves in the bore of the rotor. Confirm that the rotor mating surface is free of defects or imperfections. Take 2 (two) set screws from the plastic bag, put a drop of threadlocker (blue tube) on the threads of each set screw and screw them in.WARNING: Step 14 will install two more set screws. Thread a screw into each hole, stopping just short of the screw protruding into the inner bore of the rotor.
  8. Lubricate the shaft and rotor O-rings and slide the stainless steel rotor down the shaft. Use a non-petroleum liquid (e.g. dish soap and water solution works well) as a lubricant.CAUTION: DO NOT USE OIL, GREASE OR SILICONE AS A LUBRICANT.
  9. Refit the shaft coupling to the shaft ensuring that all safety devices provided and recommended by the coupling manufacturer are in place.
  10. Refit the shaft coupling to the gearbox, ensuring that it is fitted to the manufacturer's specifications and tolerances. Ensure that all safety devices provided and recommended by the coupling manufacturer are in place.
  11. After the shaft is in place please ensure the carbon is centered on the shaft (note the carbon ring is drilled to a larger diameter than the shaft, this is normal), ensure the Bellows boot is properly placed on the stern tube and verify that the shaft is near center in the shaft log. Next, adjust so the PSS runs true with the shaft. Finally, tighten all hose clamps around the stern tube and carbon fiber.
  12. Slide the stainless steel rotor down the shaft until it just TOUCHS the carbon. Mark this position on the shaft as the "neutral" position with a marker or piece of tape on the shaft just in front of the rotor.
  13. Shift the stainless steel rotor aft and compress the bellows the amount specified in the Bellows Compression Chart shown below, using the “Neutral” mark as a reference. While holding the bellows in the "compressed" position, then tighten the two (2) set screws against the shaft with the supplied Allen wrench (Use approximately 6 foot pounds of torque for shafts from 3/4" to 1-3/ 8" and 8 foot-pounds of torque for shafts from 1-1/2" to 3-3/4"). For example, if you need to insert the long arm of the allen wrench into the hole, a vise can be attached to the short arm to provide the torque required.
    1. Only for the "PRO" model:Install the two-piece clamp around the shaft and slide it against the rotor. Tighten the clamping screws.

    Compression diagram of PSS type A shaft seal

    shaft diameter compression amount
    3/4" bis 1-3/8"
    (20 mm bis 35 mm)
    (20 mm)
    1-1/2" bis 3-3/4"
    (38 mm bis 95 mm)
    (25 mm)

    PSS PRO compression table for shaft seals

    shaft diameter compression amount
    3/4" bis 2-1/2"
    (20 mm bis 65 mm)
    (20 mm)
    2-3/4" bis 3-3/4"
    (70 mm bis 95 mm)
    (25 mm)

    Compression diagram of PSS type B shaft seal

    * The recommended 1" compression is an average load. Up to 1-1/2" of compression can be applied if needed.

    (Video) PSS Shaft Seal: Installing Clamp Jackets & Plumbing the Seal

    shaft diameter compression amount
    4" bis 6"
    (100 mm bis 150 mm)
    1" *
    (25 mm)
  14. Take 2 (two) extra set screws from the plastic bag, put a drop of threadlocker (blue tube) on the threads of each set screw and screw one into each hole. This serves as a backup device for the first set screws. Do not reuse hollow point grub screws.
  15. Installation des Systems:
    Note:Sailboats or displacement motorboats with a propulsion speed below 12 knots can use method A or B. However, displacement boats with a bearing in the shaft log must channel water to the seal.
    1. Slow boats: (Under 12 knots boat speed under engine and without bearing in wave log).

      Using a 3/8" (8mm or 9mm) ID "submersible" hose (not included with the PSS), connect the hose to the hose barb fitting installed on the carbon and secure the hose with two (2) hose clamps guide hose to a point in the boat at least two (2) feet above the waterline and making sure the hose does not put any load on the carbon portion of the seal, keep the hose as close to the center line of the boat as possible The top of the vent hose is never below the waterline, even if the boat heels. Secure the hose with the necessary fittings to prevent it from becoming detached and falling. This hose is now a vent hose, helping to prevent there being no air enclosed in the seal.

      WARNING:Do not loop the top of the vent hose as this could result in siphoning under some extreme conditions. Make sure the vent hose is properly secured to prevent it from falling below the waterline. If the vent hose dropped below the waterline, water would enter the boat. Do not plug or block the end of the vent hose as this will prevent the line from venting.

    2. High Speed ​​Boats: (Over 12 knots boat speed under power).

      Note: Twin engine boats capable of exceeding 12 knots on a single engine must run a crossover line between the seals to ensure both seals maintain water flow while running on a single engine.

      On high-speed ships, water must be supplied to the PSS to cool and lubricate the sealing faces (i.e. at speeds in excess of about 12 knots, a vacuum is created in the stern tube and water is drawn from the PSS, resulting in a loss of cooling water which leads to can lead to overheating of the charcoal). There are several water sources for supply. Below are some non-exhaustive examples. These are examples only and may or may not apply to your particular boat.


      • The maximum water pressure should not exceed 10 PSI.
      • T-off the engine's raw water cooling line. (Note: T-Kits are available separately from PYI Inc. for 3/4", 1", 1-1/4", 1-1/2") inner tubes
      • If necessary, screw a barb into the heat exchanger drain plug.
      • Screw the barb into the exhaust manifold drain plug if the manifold is raw water cooled.
      • Add a small scoop underwater for keel-cooled boats or turn off another water intake. (Note: A valve must be installed to regulate the water flow as excessive water flow can over pressurize the PSS seal). Use appropriate “submersible” hose from the fittings on the boat and the fitting on the PSS and secure with two (2) hose clamps on each end.
      • NOTE:All plumbing work must conform to the standards and practices of proper boat installation. For example, if the pickup on the engine is below the waterline, an anti-siphon fitting must be installed in addition to other standards and practices.
  16. To test:When launching the boat, check the PSS and make sure the PSS is positioned correctly. Water should not enter the boat from the PSS seal area. Next, run the engine in gear as in normal operation. It is normal at this point to notice a very fine spray or mist from the seal and some carbon dust as the PSS requires a break-in period (see below). The PSS should not leak when at rest and should never emit more than a fine spray or mist.

Or, if you prefer, you can watch our PSS shaft seal installation video.

(Video) PSS Shaft Seal: Testing the function of the shaft Seal


High squeak:

If you hear a high-pitched squeak from the PSS shaft seal during operation, the seal may not be getting water. Check and correct the piping to the seal.

CAUTION:If the seal has run dry, be careful! The surfaces (stainless steel rotor and carbon) can be very hot.

Spray or mist during operation after the break-in period:

The dimensions given in the “Bellow Compression Chart” are average values ​​and are intended as a guide. The EXACT amounts of compression required may vary due to different types of engine mounts and the water pressure being supplied to the gasket. If you notice spatter or mist after the break-in period, make sure the boot is properly compressed. If this is the case, add 1/4 inch of compression to the gasket and soon the fog should clear. Keep adjusting until the spray or mist stops.

Drops at rest:

Assuming the PSS seal is dripping at rest, there is likely debris on the sealing surface between the stainless steel rotor and the carbon flange. To remove these debris from the gasket, gently insert a clean rag between the two surfaces (note: if the boat is in the water some water will get into the boat at this point) and run the rag around the gasket . As you do this, the incoming water will flush out the impurities. Remove the rag from the gasket and the leak should stop.

break-in period

On average, the PSS requires approximately one (1) hour break-in period, which allows the carbon flange to polish the mating surface of the stainless steel rotor. During the break-in period you will notice a very fine mist sometimes associated with black dust emanating from the PSS. Under normal conditions, this will stop after an average of one (1) hour of use.

(Video) What is a PSS Shaft Seal?

Limited Warranty / Limitations of Remedies and Liability

P.S.S. (Packless Sealing System) shaft seal

Grant of the Limited Warranty.The PSS (Packless Sealing System) shaft seal ("PSS") is warranted by PYI, Inc. ("PYI") to the original purchaser only to be free from defects in material and workmanship under normal use and service for a period of three years ( 3) Years from the date of first use or delivery, whichever comes first. During the Warranty Period, all genuine parts subject to this Limited Warranty that are determined by PYI to be defective in material or workmanship will be repaired or replaced by PYI or its authorized agent, at its option, free of charge, except for dealer's shipping and handling charges and labor (if applicable). ) that are not covered by this Limited Warranty. Any part repaired or replaced under this Limited Warranty will be void at the end of the original warranty period.

Limitations of the Limited Warranty.This Limited Warranty does not apply to PSS that: (i) have been modified in any way that does not conform to the shaft seal design as supplied, (ii) have been improperly installed and/or maintained, (iii) are incompatible with parts or components manufactured by any boat or application not supplied by PYI, regardless of the cause of failure or incompatibility of such part or component, (iv) is used for purposes other than those for which it was designed and/or (v) is subjected to abuse, neglect or accidents. To obtain warranty service, the PSS, together with proof of purchase or other dated proof of purchase showing the shaft seal model number, must be presented to an authorized PSS dealer during the warranty period. If you need help locating an authorized PSS dealer, please contact PYI at:

PYI, Inc.
12532 Beverly Park Street
Lynnwood, WA 98087

Except for the limited warranty expressly provided above, to the fullest extent permitted by law, PYI and its suppliers make no warranties, express or implied, and disclaim all warranties, duties and conditions, express, implied or statutory, with respect to the PSS, including but not limited to all implied warranties of merchantability, against latent defects, fitness for a particular purpose or conformity with the description.

Limitation of Remedies.In the event of a breach of the limited warranty set forth above, PYI or its authorized representatives shall, at PYI's sole option, either repair or replace the failed PSS. If, after notifying PYI in writing of any defect, malfunction or other failure and a reasonable number of attempts to correct the defect, malfunction or other failure, the remedy fails of its essential purpose, PYI will refund the purchase price paid to PYI in exchange therefor the return of the sold item(s). This refund is PYI's maximum liability. THE FOREGOING REMEDY SHALL BE BUYER'S SOLE AND EXCLUSIVE REMEDY AGAINST PYI, REGARDLESS OF THE THEORY, WHETHER IN CONTRACT, BREACH OF WARRANTY, TORT, INCLUDING WRITTEN LIABILITY, OR NEGLIGENCE, OR OTHERWISE.

Limitation of Liability.To the maximum extent permitted by applicable law, PYI and its suppliers expressly disclaim any liability for incidental, special, indirect or consequential damages, howsoever caused. This disclaimer applies to any legal theory under which damages may be sought.

Note:This limited warranty gives you specific legal rights, and you may also have other rights which vary from state to state.

Copyright © PYI, Inc. All rights reserved. No part of this document may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language or computer language, in any form, without the prior written permission of PYI, Inc.

PYI, Inc. makes no representations or warranties, express or implied, with respect to this document or the content contained herein and expressly disclaims any implied warranties of merchantability or fitness for a particular purpose. In addition, PYI, Inc. reserves the right to revise this document and make changes to its contents from time to time.

(Video) How to Install a PYI PSS Shaft Seal


1. PSS FAQ's
(PYI Inc.)
2. How To Compress A PSS Type B Shaft Seal
(PYI Inc.)
3. How To Clean A PSS Shaft Seal
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4. Max-Prop: How to install the Max-Prop Easy
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5. PSS Shaft Seal: In hull animation
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6. What Is The PSS PRO Shaft Seal?
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