PSS shaft seal adjustment

[markxengineerin]

That makes sense about the non-hard shafts. I'm used to industrial shafts always being hard chromed or case hardened, in which case set screws don't do much, new or not. I suspected my shaft was hard, because the set screws left no visible mark. But I didn't tighten them, that would be the previous owner, maybe they were loose or re-used.

In any case, relying on set screws to keep a shaft in place seems kind of wonky, despite the fact that it seems to work for everyone, so I might just coat the whole ID with bearing retainer next time. I use Loctite 620 all the time and it's a lot stronger than set screws, and also eliminates the need for O rings. The stainless shaft becomes easier to make, with no o ring grooves or set screw holes. Removal is with a propane torch, very easy. Propane is always involved with this work anyway, for me, and I think most people's shaft coupler removal requires it.

[markxengineerin]

I wonder if one could reasonably use one of the square-headed set screws often seen on shaft couplers... complete with holes in the head for safety wire.

I'm not a huge fan of those either- how about just regular bolts!? They make them with safety wire holes too, for those who don't want to drill.

[gonesail]

a shaft retention collar can help to reinforce the position of the PSS shaft seal.

[Jim Cate]

Originally Posted by gonesail

a shaft retention collar can help to reinforce the position of the PSS shaft seal.

As can a spare shaft anode...

And, for those not yet committed to a specific seal, the Manecraft seals that I've been using for some 18 years now don't have all these picky problems. A much simpler and robust system, no set screws to worry about, just a hose clamp. Check them out!

Jim

[markxengineerin]

Shaft collar with axial screws between stainless collar and shaft collar would be great- same function as set screws just way better in every single way besides packaging volume.

[Johnny D]

Originally Posted by HeywoodJ

Any chance the bellows is installed way down the stern tube so that the stern tube is inside the bellows and when you slide aft the carbon block is hitting the end of the stern tube? You might be able to tell that by feel or by loosening the hose clamps and seeing if you can compress the bellows by sliding that end forward (although that could be a bit scary in the water).

So far Heywood, you have the most plausible answer. You have any suggestions on how this could be done while the boat is in the water?

[BobH260]

Excellent information here,

https://marinehowto.com/installing-a-pss-shaft-seal/

Bob

[sesmith]

The spec I use when compressing the PSS seal on our boats with a 1" shaft is to compress it 3/4" from fully relaxed to compressed and not worry about the total length. I believe this is the spec you will find in the installation instructions with a new bellows.

I find it hard to do this by hand and usually resort to using small prybars on either side. Makes it much easier to compress it that way. You have to be even side to side with the force as any sideways pressure will cause the steel disk to bind on the shaft. That said, if you can't get it to compress 3/4" with reasonable force, you have a problem.

The set screws are cup tip ones and not the pointed screws. They should not be reused if you want them to hold. A little blue loctite is helpful, as well.

[Kolchac]

I think it should leak while under way. It should not in idle.

[svbravo]

I'm also having a leak w/ my PSS seal. I'd always assumed that it was at the interface of the 2 disks. Today I again tried to compress the bellows. I discovered that the leak is not at the interface, but from 1 of the setscrew holes! I assume this means that the inner o-ring is leaking, as I don't see how water would otherwise be leaking from the screw hole.


Any thoughts on how to stop this drip (other than hauling out to replace the o-ring?



Thanks

[osprey877]

Originally Posted by svbravo

I'm also having a leak w/ my PSS seal. I'd always assumed that it was at the interface of the 2 disks. Today I again tried to compress the bellows. I discovered that the leak is not at the interface, but from 1 of the setscrew holes! I assume this means that the inner o-ring is leaking, as I don't see how water would otherwise be leaking from the screw hole.


Any thoughts on how to stop this drip (other than hauling out to replace the o-ring?



Thanks

You wouldn’t think there would be enough water pressure to get past the Oring and two set screws sealed with loctite and yet not be leaking between the two rotors. How far below the waterline is the seal? Obvious question I know, but did you check that the screw hole actually has two set screws in it? If yes, try replacing them with new ones and use plenty of loctite and/or thread sealant on them. Good luck.

[svbravo]

The drip rate out of the screw holes actually increased after I removed the four set screws and compressed the bellows a bit more. So I think the lock tite was acting as a bit of a thread sealant as well as the thread lock. I'm quite sure at this point that the o-ring must have been damaged when the shaft was first installed, as it's been leaking slightly since the boat was launched 1-1/2 years ago.

[markxengineerin]

teflon tape around set screw? Worth a shot before haul out

[svbravo]

Excellent idea. . I had a similar thought, and had tried using a glob of the blue locktite that I had at hand. But of course it couldn’t work, since there was water in the hole. A bit of Teflon tape might stop the dripping for now, and I could do the proper repair w new o-rings when we haul out for antifoul next year. Worth a try!

[Jim Cate]

A small blob of Splashzone or other underwater epoxy should make a useful plug over the set screws and will adhere to wet surfaces.

Reading all these stories of weeping PSS seals makes me glad I used a Maneseal!

Jim