PSS shaft seals leaking when throttling up

[Mickeyrouse]

Originally Posted by chris mac

And for those curious, the coolant leak is coming from the water pump, so my guess is the bearings or shaft in there. A new pump will be installed once stateside.

Most pumps are fairly easy to repair. If you have a Johnsen or equivalent, repair kits including gaskets, impeller, screws, and seals are available. Keep the leaking pump, install a repair kit, and you’ll now have an on-board spare. Doesn’t take up much room, and you’ll have a new level of peace of mind. And keep another repair kit on board.

[sinnerman]

Are you able to move the shaft forward/back by hand? And cause a leak?

Too much fore/aft play may be a thrust bearing issue in the transmission...

Or loose coupling on the shaft...

My two cents

Cheers?

[Icarus]

Originally Posted by chris mac

We had new shaft seal installed this summer and they seem to be working well. Meaning that the bilge doesn't fill up or trigger the pump.
Recently I had a leak in my coolant system and thru the diagnosing, a friend noticed the shaft seal spurt when we engaged the transmission in forward and throttle up.
Going over the literature, it is compressed within the specs for shaft size. It doesn't leak at rest, I haven't been able to view it under way sailing or full power yet. But as I mentioned, outside of my coolant leak, the bilge hasn't been triggered.
When I physically push on the bellows I can create a gap,make it leak, with not a lot of pressure. And the other side is identical.
Is this normal? Should it be tighter?
I don't have replacement set screws, so I won't be messing with it until we get back to the states in may.
And for those curious, the coolant leak is coming from the water pump, so my guess is the bearings or shaft in there. A new pump will be installed once stateside.

I have a PSS on my propshaft ( 1⅛" dia) and certainly can't easily push the neoprene bonnet open...
The compression ought to be ¾" ...which is quite tight.
Does the shaft wobble with the engine or is there a CV/trust bearing arrangement?

[Icarus]

Maybe the prop shaft actually moves forward when engaging the gear box in to forward ?
Thus releasing the PSS bonnet pressure?

[Mauruuru]

just replaced my 12 year old one with a new one. I chose to get a whole new assembly rather than the seal kit because of its age-twice as old as they recommend. But I keep my boat on a lift out of the water when not sailing. I replaced it because the wear on the carbon seal was leaking at higher rpms and while it wasn't a significant amount of water, it was spraying around the compartment which, when it had a Yanmar diesel in it was no big deal but now that it has been replaced with an electric drive and controller was getting salt spray where it could have been an issue.

[Solarken]

How do you replace in water? Can’t pull the shaft out? I’m confused here..

Thank you

[Solarken]

WoW ��… I’m electric ⚡️ also. But I’ve not seen a spray. I have seen a dripping at rest but you can roll the shaft and it will stop.

[chris mac]

Originally Posted by Icarus

Maybe the prop shaft actually moves forward when engaging the gear box in to forward ?
Thus releasing the PSS bonnet pressure?

Somehow missed this, sorry for the late reply. Yes the prop shaft moves the engine forward against the mounts with initial thrust. Minimizing the thrust seems to have worked in the interim until I compress it prpoperly

[chris mac]

Originally Posted by Solarken

How do you replace in water? Can’t pull the shaft out? I’m confused here..



Thank you

I've bought new set screws, so will do it soon. I also bought compression split rings. So the plan is to install the split ring against the pss collar. Then I can remove the collar set screws, compress the bellows by placing a spacer between the split ring and collar(I'm thinking 1/4 to 3/8" spacer) then tighten the collar witn new set screws. After that I can move the split ring against the collar to work as a safety.
This way the bellows shouldn't ever open up more than it now sits

[Mickeyrouse]

If your engine is mounted on flexible mounts, as most sailboat engines are, it absolutely moves forward when the engine is in forward gear. The shaft seal installation instructions seek to address this by instructing the installer to slide the collar rearward by 1/4” thus compressing the bellows before securing. And as the seal face wears in the course of normal service the gap between the collar and seal face will tend to wear, thus requiring periodic adjustment. I suggest replacing the socket set screws with grade 8 hex head machine screws. Liberally coat the threads with grease or Never Seize. You can torque the hex head machine screws much more safely than soft stainless set screws.
I have cammed the set screws out while tightening them in the collar. Of all the cramped, difficult places to work on a boat, the shaft alley behind the shaft coupling is the worst. I had a merry time carefully drilling the old set screws out working upside down left-handed.

[Solarken]

I’m hard mounted all electric ⚡️. Maybe I just need to shove the motor Back a ¼”??? Will check on that. It’s a 4 plus hour ordeal to pull the motor. And I have to go under to secure the shaft from moving forward!

Then move the collar. I think if I can just move the motor back? We will see!! Carbon may have worn in 5 years from motor insulation.

[GreenWave]

Originally Posted by markxengineerin

One thing to check for is motion of the bellows while the shaft is spinning. If there is an alignment problem with one or more of the parts, the bellows is forced to move (vibrate noticeably) enough that there can be leaks. I had this issue and it was fixed with better alignment.

This 100%. My pss seal started leaking a couple years ago. Found a bad motor Mount. Once that was fixed all was good.

[roryboy]

If your using a PSS dripless shaft seal, with a Yanmar that has a v-drive, your gonna see leaks. There is just too much movement in those big cushy mounts.

[MicHughV]

Just my 2c here...
The PSS shaft seal uses external water pressure to keep the bellows against the collar.
But.....if the shaft/prop is not very deep below the water for any reason, it also means that there will be reduced water pressure to keep the bellows firmly seated.
Could be other problems too, some tiny dirt particles, a bit of scour, who knows, but the entire premise of the PSS shaft seal is to have two perfectly mated surfaces.
The mating surfaces do require water as the "lubricant" so it's not unusual yo see a tiny bit of spray.
I had the PSS shaft seal on my first boat, and it gave me remarkable service for many years. Never had any issues, leaks, etc, but my prop shaft was a good 3' below the surface.