Changing Dripless Seals

J

JeffR

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I've had some problems with my dripless seals spraying. I've adjusted to - and slightly past - the recommended compression of the bellows, followed all of PYI's maintenance recommendations, and they still spray. After speaking with PYI, I believe it's time to replace the bellows.

I'm pretty mechanically inclined, and do all my own maintenance/repairs unless it's something I know is outside of my abilities. To replace the seals I obviously need to separate the shaft coupling, and remove the shaft-side coupling half from the shaft. I've never done any of that. What do you think, is this something within DIY territory, or should I have an "expert" (that's actually the part the scares me the most!!) do it for me? BTW - yes, I know this needs to be done while out of the water!! :)
 
Main challenge is getting the coupling off. But I've had good luck in the past. Also, depending oh how far you need to slide your shaft to allow the R&R of bellows, you may have to pull the prop to slide shaft past rudder.

I replaced my shafts last year and lets face it, while it's grunt work, it isn't rocket science...you'll be fine!
 
Go for it. You have nothing to lose. If you find you need help then call a pro. How long since the seals where installed? If not to long you should not have much problem getting the coupler off. I installed a set on a previous boat. The coupler had not been off in over 20 years. It took a torch to heat it and a big efin hammer.

It would all depend on how much access you have.
 
Bare in mind it recommended that you don't reuse a coupler. Unless it's of the split coupler type.

And you could change it out with the boat in the water.
 
If you have to pull the props... When was the last time the cutless bearings were changed?
 
Get a quote for the work and then decide, it's. Not rocket science but it's just unpleasant work. If the couplers are clean it s easy, but if it's rusted up it can get interesting.

I m not sure I'd try pulling a Bellow on those seals in the water...

How old are the bellows? Are you sure it s not just dirt or something on the seal surface?
 
Pulling the shaft out of the coupling is either a long and tedious process, or a quick ten minutes if you have a shaft slide hammer most dyi's don't. I always borrow my yards puller. I would: only do the socket trick if I was in an emergency. Hate that. You also need to deburr your shaft before trying to slide the shaft seal on or off unless you want to find you cut the oring.

But before you do all this, tell me why you think you need to swap bellows? The bellows don't provide the dynamic seal, they simply provide tension to the face seal. Water spray means the faced seal itself is weeping. You may have to swap or machine that, at a minimum. Have you tried using sandpaper to polish it yet..
 
Go to Youtube and enter "pyi shaft". There's some info there. Maybe some that is helpful. Good Luck and please let us know how things go.
 
"But before you do all this, tell me why you think you need to swap bellows? The bellows don't provide the dynamic seal, they simply provide tension to the face seal."

The bellows do harden over time and will not provide the tension needed to hold the seals together.
 
Thanks for all the feedback. As noted, not going to do this work with the boat in the water. I'd like to think I'm just that good, but...this will be a winter storage project!!!!

I've tried the possible fixes as suggested by multiple conversations with PYI - sandpaper the faces, burp the seals to remove dirt, additional compression on the bellows, etc. None have provided a lasting fix. In addition, they don't drip or weep, they spray. PYI has stated and it's on the their website, that the bellows will eventually take a set and will stop providing the necessary force. I want to say something like 6 years, but I'd have to look to be sure, and mine are now 9 years old.

My coupling is a brass coupling. I have yet to find any type of set screw as an additional safety for holding the coupling on, and if that's the case, I'd think the press would have to be significant to ensure it never loosens. That's what concerns me about trying to remove it (and re-install, to be honest). And I agree that the socket approach worry's me. I'd think a puller set up to pull on the base of the coupler rather than using the bolt holes or flange in any way would be safer to prevent damage.

How much time, or what should I expect for cost if I have yard do it?

Additional thoughts? What am I missing?
 
The reason you're not seeing set screws may be because the coupling is held on via a large nut that screws on to the end of the shaft. If it's there you'll see it after you disconnect the coupler and slide the shaft back.
 
Sounds like you have this pretty we'll thought out. I'm not familiar with that style of coupler so won't comment. Typically a yard can have a shaft out of a coupler in less than an hour. Another hour to replace bellows and drive the shaft back. Should really not be too bad at all if it goes smoothly. As far as being good enough, that's not an option to do in the water with this style seal. You could easily and quickly sink yourself if you tried. This is not the same as packing a gland when in the water. It's one downside of drip less seals.
 
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