Drive train noise, stuffing box leak, etc

[ndutton]

My preference is contrary to all the experts who say the shaft has to fit so tight in the coupler that it has to be beat into place by the likes of John Henry. When I did them I would dress the inboard end of the shaft until the coupler could be slid on by hand. What held it in place were two hardened set screws driven into generous dimples drilled into the shaft and safety wired after they were tightened. I never lost a shaft in reverse.

As for PSS seal or conventional stuffing box, opinions vary and they're worth what you pay for them ($0.00). I'll suggest the major factor in the decision making process is access to the stuffing box. If access is difficult, a PSS may be the best money you ever spent. With good access, either will work and as you've seen, repacking a stuffing box is pretty easy even in the water.

Not that it matters to anyone other than me but there will never be a PSS on a boat of mine. In the 1980's I was considering one for a boat I was building. I ran up against the normal chatter, ask 3 sailors and get 4 opinions. I gave the production manager at Islander Yachts a call, an old friend whose opinion I respected. I knew they were using a PSS type seal on their new Islander 34 because of access problems under a V drive engine so here was a guy with first hand experience with several installations. He said he wouldn't install one of those $%#@& things unless a gun was held to his head. The problems they experienced weren't longevity based (new boats of course) but rather sealing face issues. When they're polished like new they work fine but once scratched they turn into a pump slinging water all over the place. It's entirely possible, maybe even probable, his employees weren't taking the care they should have during installation but his opinion was good enough for me.

[Al Schober]

A new coupling will just slide over the end of the shaft - it's not a force fit. An old coupling is hard to remove because of corrosion of the coupling. The corrosion products fill the interface. Clean up the old coupling and it will slide back into place and work fine.
The old shaft, even though scored, may be usable. First, consider the possibility of moving the stuffing box to a new location by using a shorter or longer hose to the stern tube. Then make sure the old shaft is straight. A gradual bend over the full length is removable. A short kink at the aft end taper is hard to correct and will have a adverse affect on the propeller (will make the propeller seem to have bent blades.
Plus one on having the coupling set screw seat into a good dimple in the shaft. This dimple is made with a drill bit the size of the screw, and drilled deep enough to cut it's full diameter. I've seen more that one shaft pull out of couplings because the shaft wasn't drilled.
Face seals are good things but are susceptible to scoring from grit in the water. The worst grit is the stuff you see in glacial runoff. This grit comes from the outside water trying to get into the boat. The trick to getting long life from a face seal is to feed it clean water. Water from the water pump discharge is run through a filter and then fed to the stern tube just aft of the seal. We're talking a very small flow - just more than the seal drips.