Fix for PSS Dripless Shaft Seal Leak

[wcconway]

Our PSS dripless was dripping....a LOT!

First, let me give credit to Ray Edwards, S/V Maria C350 Mark I, who we often call when experiencing a problem. He knew just what to do. And, it was quick and easy if you exclude the time it takes to remove the mattress from the aft cabin.

On the stainless steel "collar" there are 2 holes for 2 sets of "set" screws (each of the 2 sets have 2 "set" screws stacked one on top of the other). Over time. the bottom ones become worn pressing against the shaft and will allow some slippage and expansion of the shaftseal, thus the dripless starts dripping. We first noticed this when the bilge pump was operating more often than usual. Using a 1/8" allen wrench, remove the first set of "set" screws, exchange the order (the difference in the worn and unworn set screw is obvious) and tighten down. Do the same for the 2nd set of "set" screws. By doing this, the unworn "set" screw is now pressing against the shaft to hold the PSS Shaftseal in place.

We called the manufacturer for 8 replacement set screws for our spare parts inventory. They sent these free of charge. He also told us to measure the entire length of the shaftseal and to make sure it was compressed to ~6 1/4". Ours had expanded to 7 1/2" which didn't provide enough pressure to keep it from dripping. After exchanging the set screws, we "compressed" the shaftseal to 6 1/4" and tightened down the "set" screws. We are again dripless. NOTE: Our Mark II, Hull 467, has a thru hull dedicated to the shaftseal, so be sure to close and reopen while performing this maintenance.

Mfg. web site: http://www.shaftseal.com/en/categories

We have always had a little water in our bilge and we now believe this was the culprit. Our bilge is now dry.

[TBOT422]

Oh, Gee Thanks Wally. Something else for me to go check.

Seriously, Thanks. It's this type of information that makes this forum great. The combined learning of the group instead of having to learn everything on our own.

Gary

[KenKrawford]

Wally, RE: the 6 1/4" compression of the bellows - are you measuring from the front to back edge of the rubber bellows or from the stainless collar to the back edge?

Thanks.

[nybor]

wow! so much great info! Since I am changing my damper plate and have to loosen the collar set screws, I can verify that the bellows is at the correct length. Am waiting to hear about where to take the measurements from-to.

thanks
dave

[KenKrawford]

The 6 1/4" measurement is from the front to back edge of the bellows.

[nybor]

Hi all. boy, it is HOT here in Florida! 77 degrees. (Sorry Leigh)
anyway, can someone PLEASE explain the plumbing of the PSS shaft seal setup? Like a previous poster, mines has a "thru hull dedicated to the shaftseal" valve. What is its purpose? does water come in or out of the tubing attached to the PSS nipple? does it hurt the seal to run the engine in gear but with the boat still secured in the slip? (i wanted to check the temp as it rotated alone on board)

thanks in advance.

dave

[leigh weiss]

Dave,
Thanks for the warm thoughts!
My guess..... is that the through hull fitting acts as the input for the cutlass bearing discharge.
While sitting at the dock with no shaft rotation the need for lubrication of the cutlass bearing is minimal. If you engage the transmission (F or R) the center of the shaft might be at a slightly lower pressure drawing water out of the cutlass, from both the action of the prop and the movement of the boat. My boat has a water injection fitting from the seawater pump. So this is a SWAG.
I don't think we ever found the exact reason the factory made the change or the theory of operation.

Leigh Weiss

Brisa #155

[tranquilcat42]

Thanks to all for the great information in this blog.

Does anyone know the shaft diameter on the 350's? I need to order the maintenance kit and nothing came with Hull #187 regarding PSS.

Thanks

[russp]

Shaft diameter is 1".

Russ Peel
Avalon #150

[tranquil]

Thanks Russ!

[Windseeker]

Very helpful post. This is probably be the major source of my bilge water problem. It doesn't always leak, but it has been a pronounced problem this year. I was able to use a prybar and move the collar about 1/2" away from he transmission and retighten the screws. It was resting on the transmission flange. This total dimension should be 6 1/4"? I need to compress this another 1/2 inch?

[KenKrawford]

Wind Seeker, the correct length for the compressed bellows is 6 1/4". From the picture you attached, it appears that the aft end of your bellows only has 1 hose clamp. There should be 2 clamps on the shaft log and 2 on the carbon flange. You're probably aware but there are 4 set screws securing the stainless rotor. They are stacked in pairs on top of each other. It's important to completely remove the top ones, slightly loosen the inner ones and then compress the bellows. PYI recommends replacing the set screws when adjusting the bellows as they make a small dimple in the shaft when tightened.

[russp]

Post removed by author because information was incorrect and misleading.

Regards
Russ Peel
Avalon #150

[leigh weiss]

Russ,
Can you tell me the part number for the PSS shaft seal you used.
I want to install a flex coupling between the flanges but do not have enough room because the bellows is two long.Your shorter bellows might be the ticket!
This I hope will move the prop further aft away from the dead wood hopefully increasing prop efficiency and reducing noise..
Thanks

[leigh weiss]

Russ and all,
Just got back from sailboat show and met with Fred Hutchison of PYI. He said that they make only one size PSS bellows for our shaft seal. It is around 6" long and not 4.5".
He can supply replacement bellows but only of the one larger size he makes. If you have a bellows that is shorter than the original (4.5")l, I would like to find it and see if it will fit with the rest of the seal system.
Thanks for the great find.

[russp]

Hi Leigh et al,

I was getting quite confused here and I apologise because I have been confusing others along the way. The original PYI information that I had to go on when I took possession of the boat was a diagram showing TOTAL length of the seal as 6.975" (i.e. bellows + carbon face + rotor), and this compressed down to 6.225" when in use.

Having now taken the time to go back through my records like a grown up instead of relying on vague memory, I find that my old bellows (just the rubber component) are about 5" uncompressed, and 4 1/4" compressed and I couldn't reconcile these measurements with my memory of the length being 6"+.

So, no mystery, just my laziness (sorry), the "bellows" I have installed are 5" uncompressed, the old bellows were 5", and the 6"+ is the TOTAL length of the seal assembly. All depends on getting common agreement about where the measurement applies!

Russ

[leigh weiss]

Russ,
Thanks for the clarification.
My hopes are dashed about adding a flex shaft coupling and moving the prop aft this way.
I went to the local Catalina dealer and looked at a new boat with the same hull configuration as ours.On this boat, the prop is about 2" aft of the end of the cutlass bearing away from the deadwood. Is this a new design or just on this boat? This might be a modification when it is time to change the shaft.
Thanks again.

[ps23435]

Yet another leaking PSS shaft seal question... our shaft seal has begun leaking...again. It happened to a lesser degree a couple years ago but after burping, flushing and cleaning it all dried up. We were completely dry all last year! All of a sudden the leaks started again and at a greater rate. After some troubleshooting, it seems we don't have any water coming through the seal when at the dock or when sailing and the shaft is locked (reverse). When motoring there appears to be a small amount of water coming in at low to moderate RPM. However, when we get to 2500 RPM there is a steady stream of water flowing in from the face of the seal. I've again burped, flushed, cleaned the seal face with no change. I've read all the posts above and noted the comments about the proper compression for the bellows at 6.25". Note from our pictures that ours is compressed much greater than that, about 5.5" from the face of the carbon flange to the back of the bellows. I've also noticed that the 2 upper set screws in the stainless steel rotor are protruding above the surface of the rotor. I can't say if this is new or if it has always been that way...just never noticed before. To replace the set screws and reset the rotor I assume the boat needs to be hauled and out of the water? This is the original seal 9 years old so is overdue for maintenance anyway. Any thoughts appreciated!

[KenKrawford]

Pete, I'm not sure why your seal is leaking with that much compression. The set screws that hold the SS collar in place sit below the surface of the collar on my boat. I assume you are aware that there are 4 screws in the collar and consist of 2 pairs of screws stacked on top of each other. The outermost one must be completely removed from the collar in order to access and tighten the one that contacts the shaft. You can replace the set screws with the boat in the water by making sure that there is a little tension on one pair of screws to keep the bellows in position. Replace the other pair. Once they are tight you can replace the remaining pair.
I'd give PYI a call regarding the fact that you still have a leak in spite of the over compressed bellows. Any chance the bellows itself is cracked and leaking? If so you could have a potential disaster looming.
Keep us posted on what you find out.

[nybor]

Hi All. I am still at the hospital getting a blood transfusion from all that I lost replacing my PYI over the last MONTH! The worst part was removing the flange coupling. (from the photo in the previous post (Photo 1), I am afraid when it gets time to replace your dripless PYI, you will NOT be able to get the coupling off. We tried everything (and I do mean that) and mine looked perfect. Finally had to cut it off and get a new coupler ($351) (However, I saw that they sell a two piece one for a lot less). I defy anyone to re-install both the PYI and coupler by themselves. I must have gone down the ladder (and up) 100 times as I tried to line up the keyways on the shaft and coupler.

What I think happened was when the original one was installed, PYI says a fine mist of water will be emitted until the two faces seal themselves. This mist coated the coupler and over time got down thru the two set screws (really bolts) to rust in place.

So, I am installing a 55 gallon barrel of grease with a hose to the coupler. It will inject a steady stream of heated grease (I had to also purchase a 55,000 BTU furnace) into the area, completely submerging the coupler, PYI, transmission and whatever else is down there!

Please don't contact the Coast Guard if you see me and a 100 mile oil slick trailing my boat. (I just like to cook a lot)