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.
The PSS Shaft Seal 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 that you have all the required tools and additional equipment on hand before beginning installation.
The PSS Shaft Seal is a mechanical face seal that is created between the flat surfaces of the rotating stainless steel rotor and the stationary carbon flange. The stationary carbon flange is attached to the vessels stern tube with hose clamps and the carbon flange is attached to the front side of the bellows with hose clamps. The stainless steel rotor is fit 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 (pre-load) maintains contact between the faces and allows the PSS to compensate for the thrust from the propeller. The carbon flange is bored larger than the shaft diameter allowing it to “float” around the shaft and thus compensate for most misalignment and vibration problems. The stainless steel collar is sealed to the shaft by two o-rings that are recessed into the bore of the collar. These o-rings rotate with the shaft and stainless steel rotor and do not experience wear during operation.
Shaft Diameter: 3/4" to 1-3/8" (20mm to 35mm) = 3/4" (20mm) of compression
Shaft Diameter: 1-1/2" to 3-3/4" (38mm to 95mm) = 1" (25mm) of compression
In all cases, the boat must be out of the water to perform this installation.
Plumbing the system:
Note: Sailboats or displacement powerboats with a powering speed below 12 knots can use either method A or B. However, displacement boats with a bearing in the shaft log must plumb water to the seal.
Low speed boats: (Under 12 knots of boat speed under power and no bearing in the shaft log).
Using a 3/8" (8 or 9mm) I.D. "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 centerline 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.
WARNING: 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.
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, while running on only one engine.
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 over heat). There are multiple sources of water for the supply. The following are a few non-exhaustive examples. These are examples only and they may or may not apply to your particular boat.
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.
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.
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 black dust coming from the PSS. Under normal conditions, this will stop after an average of one (1) hour running time.
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