PSS Shaft Seal
For Shafts: 3/4" to 3 3/4" (20mm to 95mm)
IMPORTANT INSTRUCTIONS - READ BEFORE STARTING!
IMPORTANT!-BEFORE STARTING YOUR INSTALLATION CAREFULLY READ THE
FOLLOWING WARNINGS AND INSTRUCTIONS.FAILURE TO PROPERLY FOLLOW THE
WARNINGS AND INSTRUCTIONS COULD LEAD TO PERSONAL INJURY OR EVEN
DEATH,OR PHYSICAL,ENVIRONMENTAL OR PROPERTY DAMAGE.
- READ AND FOLLOW THE INSTRUCTIONS THOROUGHLY! The PSS (Packless
Sealing System) Shaft Seal (PSS) you are preparing to install
is a through-hull fitting that protects against water from entering
the boat where the shaft enters the hull, when properly installed
and maintained. Make sure that you or your designated installer is
a qualified professional, knowledgeable and skilled to install the
PSS correctly, and you have all the required tools and additional
equipment on hand before beginning installation.
- Install the PSS ONLY with the boat out of the water.
- DO NOT USE oil, grease (petroleum products)or silicone products
at any time during the installation. Use soap and water to
lubricate the o-rings of the rotor when sliding it down the
- Clean the seal area of your boat so you do not contaminate the
seal surface with dirt, oil or other foreign matter.
- Do not damage or scratch the face of the carbon or the face 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 sets screws in each hole).If you must move the
stainless steel rotor, make sure to remove the top set screws in
order to access
the bottom two set screws.
- There should be a total of four (4) hose clamps securing the
- Do not re-use the supplied cupped pointed sets screws. If
multiple tightening has flattened the cupped-point set screw,
replace the affected screw with a new one.
- Do not tighten or replace the installed nylon hose barb fitting
with a metallic fitting (bronze or stainless steel).Metal hose
barbs will damage the carbon and destroy the PSS.
- Do not slide the aft bellow cuff too far down over the stern
tube. The leading edge of the stern tube could cause damage to the
inner ribs of the bellow and improperly limit the bellow movement
- If fitting a vent line (boats under 12 knots),do not run a loop
at the top end of the hose as this could promote a siphon and water
- If the boat sits idle for a long period of time (generally 3
months or more),it is necessary to move the carbon face back to
allow a small amount of water to enter the boat.
- As with any hose under the waterline, the PSS bellows must be
inspected on a regular basis (i.e., no less than at least every 6
months under most circumstances) and checked for any signs of
deterioration (cracks, splits, tears, brittleness or other
signs).Upon any sign of deterioration the bellow must be replaced.
As preventive maintenance
the bellow should be replaced no less than every six (6) years,
regardless of its apparent condition.
- Do not allow any petroleum-based liquid or corrosive material
to come in contact with the PSS. Take care to ensure that this does
not occur for example when performing any general maintenance, or
winterizing the engine.
- Make sure the shaft is near centred in the shaft log.
- Do not use an ozone generator (e.g., air cleaner)in or around
your boat. The extra ozone will speed up the deterioration of any
rubber product, including the PSS bellow.
- The bellows will need more frequent inspection and replacement
in an environment where non-sealed batteries emit sulphuric acid
vapours. Sulphuric acid vapours will accelerate deterioration of
any rubber materials including the PSS bellows.
- Propeller Shaft
- Shaft Log (Stern Tube)
- Stainless Steel Hose Clamps (4)
- Bellow (1)
- Carbon Graphite Flange (1)
- Stainless Steel Rotor (1)
- Stainless Steel Set Screws (5 total/4 for rotor,1 spare)
- Nitrile O-Rings (2 in rotor/2 spare)
- Nylon Hose Barb Fitting
IN ALL CASES,THE BOAT MUST BE OUT OF THE WATER TO PERFORM THIS
- Unbolt the shaft coupling from the transmission coupling.
- Remove the shaft coupling from the shaft. Coupling styles will
vary by manufacturer. Some couplings use set screws to keep the
coupling in place, while others use a roll pin and others use a nut
(always use the appropriate tools and procedures for your
- Remove the old stuffing box and packing material. There are
three types of packing glands that can be found on most
boats:"Classic", "Bolt On" and "Threaded".
- Clean the entire exposed portion of the shaft with very fine
sand paper (#400 or #600 grit)in order to remove any debris or
rough edges. Pay particular attention to the keyway located at the
forward end of the shaft, where the stainless steel rotor will
pass. The shaft and keyway must NOT have any sharp edges that could
damage the o-rings upon installation.
- Slide the open end of the bellow and its hose clamps down the
shaft and onto the bare stern tube and make sure the bellow has a
proper fit over the shaft log. Once in place the bellow should
overlap the stern tube by the same amount as the bellow cuff so the
hose clamps will properly tighten the bellow to the shaft log.
WARNING: Do not slide the bellow cuff too far down and over the
stern tube. If the bellow is slid too far onto the stern tube the
forward edge of the stern tube could damage the inner ribs of the
bellow and improperly limit the bellow's travel. Tighten the hose
clamps to secure the bellow to the stern tube.
- Make sure the carbon flange is in place on the forward end of
the bellow and that the two hose clamps properly secure it. Also
confirm that the carbon is free of any defects or imperfections on
its polished face.
- Remove the stainless steel rotor from the protective pouch.
Verify that there are two (2)o-rings placed into the o-ring grooves
inside the bore of the rotor. Confirm that the mating face of the
rotor is free of any defects or imperfections. Take two (2)(Two
Only) of the set screws from the plastic bag and thread them into
the rotor holes. Save the remaining set screws for use later during
installation. Thread one screw into each hole, stopping just short
of the screw protruding into the inside bore of the rotor.
- Lubricate the shaft and o-rings of the rotor, and slide the
stainless steel rotor down the shaft. Use a petroleum free liquid
(e.g., a dish soap /water solution works well)as the lubricant.
Caution: DO NOT USE OIL, GREASE OR SILICONE AS THE LUBRICANT.
- Re-attach the shaft coupling to the shaft and make sure that
all the safety devices provided and recommended by the coupling
manufacturer are in place.
- Re-attach the shaft coupling to the transmission making sure
that it is installed to the manufacturer specifications and
tolerances. Make sure all the safety devices provided and
recommended by the coupling manufacturer are in place.
- Now that the shaft is in place, verify that the carbon is
centred on the shaft (note the carbon ring is bored at a larger
diameter than the shaft), verify that the bellow cuff is properly
placed on the stern tube and verify that the shaft is near centre
in the shaft log. Adjust accordingly. Tighten all the hose clamps
around the stern tube and the carbon.
- Slide the stainless steel rotor down the shaft until it just
TOUCHES the carbon. Mark this position on the shaft as the
"neutral" position with a marker or a piece of tape on the shaft
just in front of the rotor.
- Sliding the stainless steel rotor aft, compress the bellow by
the amount indicated on the bellow chart, using the "neutral" mark
as a reference point..While keeping the bellow in the "compressed"
position,, tighten the two (2)set screws against the shaft with the
provided allen wrench (Use approximately 6 foot pounds of torque
for shafts 3/4" to 1 3/8" and 8 foot pounds of torque for shafts 1
1/2" to 3 3/4"). If you need to insert the long arm of the allen
wrench into the hole, a vice-grip, for example, may be fitted on
the short arm to help provide the required torque.
- Remove from the plastic bag two (2) additional set screws, and
thread one into each hole and tighten them against the first set
screws. This will act as a locking device for the first set
Plumbing the system:
15A. Low speed boats :(Under 12 knots of boat speed under power).
Note: Sailboats or displacement powerboats with a powering speed
below 12 knots can use either method A or B.
Using a 3/8 " ((8 or 9 mm)ID "underwater rated " hose ((not
provided with the PSS), connect the hose to the hose barb fitting
installed on the carbon and secure the hose with two (2)hose
clamps. Run the hose to a point in the boat at least two (2)feet
above the waterline, making sure that the hose does not apply any
load on the carbon part of the seal. Keep the hose as close as
possible to the centreline of the vessel so the top of the vent
hose is never below the waterline, even if the boat heels. Secure
the hose in place with the necessary fittings that insure it will
not pull free and drop. This hose is now a venting hose that will
help ensure that no air is trapped in the seal.
WARNINGS: Do not run a loop at the top end of the vent hose as
it could start a siphon action in some extreme conditions. Also
make sure the vent hose is properly secured from falling below the
waterline. If the vent hose were to fall down below the waterline,
water would come in the boat. Also do not plug or block the end of
the vent hose, as this would prevent the line from venting.
15B.High-speed boats :(Over 12 knots of boat speed under power).
Note: Boats that can exceed 12 knots on a single engine must run a
crossover line between seals to ensure both seals maintain water
flow. For high-speed vessels it is required that a water supply be
plumbed to the PSS for the purpose of cooling and lubricating the
seal faces (i.e., at over approximately 12 knots of speed a vacuum
is created in the stern tube and water is drawn away from the PSS
resulting in a loss of cooling water that may cause the carbon to
overheat).There are multiple sources of water for this supply. The
following are a few non-exhaustive examples. These are examples
only and they may or may not apply to your particular boat. -T-off
the engine raw water-cooling line.(Note: T-kits are available
separately from PYI, Inc for internal hose 3/4",1",1 1/4",1 1/2")
-Thread a barb fitting into the drain plug of the heat exchanger if
applicable. -Thread a barb fitting into the drain plug of the
exhaust manifold if the manifold is raw water-cooled. -Add a small
scoop under water for keel-cooled boats or t-off another water
pick-up. (Note: A valve must be installed to regulate the water
flow as too high a water flow may over pressurize the PSS seal).Use
an appropriate "underwater rated " hose from the fittings on the
boat and the fitting on the PSS and secure them with two (2)hose
clamps at each end. NOTICE: All plumbing must follow the standards
and practices of proper boat plumbing. For example, if the pick-up
on the engine is located under the waterline, an anti-siphon
fitting must me installed, in addition to other standards and
Testing: When launching the boat, inspect the PSS and make
sure the PSS is properly in place. Water should not be entering the
boat from the PSS seal area. Run the engine in gear as in a normal
operation. It is normal at this time to notice a very fine spray or
mist coming from the seal and some carbon dust, as the PSS requires
a break in period (see below).The PSS should not be leaking at rest
and should never spray more than just a fine spray or mist.
If you hear a high-pitched squeal from the PSS shaft seal during
operation, the seal may not be getting water. Review and correct
plumbing to the seal.
CAUTION: If the seal has run dry use caution! The faces
(stainless steel rotor and carbon)may be very hot.
Spray or mist during operation after the break in period:
The dimensions provided in the "Bellow compression chart" are
average figures and are provided as a guide. The EXACT compression
amounts required can vary due to different types of engine mounts
and water pressure being fed to the seal. If you experience any
spray or mist following the break in period, make sure that the
bellows had been compressed properly. If so, add an additional 1/4
" of compression to the seal and soon the mist should disappear.
Keep adjusting until the spray or mist stops.
Dripping at rest:
If the PSS seal drips while at rest then it is likely that
foreign material is on the face of the seal between the stainless
steel rotor and the carbon flange. To clean this foreign material
from the seal, insert a clean rag carefully between the two faces
(Note: some water will come into the boat at this time if the boat
is in the water) and work the rag around the seal. As you do this,
the incoming water will flush the impurities. Remove the rag from
the seal and the leak should stop.
On average, the PSS requires approximately one (1) hour of break
in time, which allows the carbon flange to polish the mating face
of the stainless steel rotor. During the break in period you will
experience a very fine mist, sometimes associated with a back dust
coming from the PSS. Under normal conditions, this will stop after
an average of one (1) hour running time.