Shaft Seal Leakage

[sailorboy1]

My shaft seal isn't one of those fancy units with the tube, just a bellows and rotating ring. It wasn't leak much, just a small amount of spray coming off it while the shaft is spinning, but it adds up to a gallon of so after a few hours. I don't think it leaks when not turning, but am checking into this more.

So the question is: if you don't have one of the "drip less" shaft seals how much leakage is normal?

[Blue Stocking]

None of them are "dripless" if the compression is not correct on the bellows.
Is yours the carbon ring against st. steel type? If so , are the faces damaged.
What does the manufacturer say?

[DHHong Kong]

Don, it sounds like you may have one of those "fancy units" - the "un-fancy units" are the tried but true gland packings with adjusting nut but you say you have a bellows and rotating ring. If you can move the the rotating wear ring down the shaft to load up the bellows a bit and put more pressure on the seal face you may stop the leak. The bellows/face seal should not leak at all - we have a pair of PYI bellows/face seal units that don't drip at all after four years - but a gallon every few hours is perhaps a bit too much?? Try the collar adjustment - they usually have two or three allen headed grub screws holding them in place on the shaft.

[Blue Stocking]

Originally Posted by DHHong Kong

Don, it sounds like you may have one of those "fancy units" - the "un-fancy units" are the tried but true gland packings with adjusting nut but you say you have a bellows and rotating ring. If you can move the the rotating wear ring down the shaft to load up the bellows a bit and put more pressure on the seal face you may stop the leak. The bellows/face seal should not leak at all - we have a pair of PYI bellows/face seal units that don't drip at all after four years - but a gallon every few hours is perhaps a bit too much?? Try the collar adjustment - they usually have two or three allen headed grub screws holding them in place on the shaft.

If the collar has slipped up the shaft a bit (it happens), you may get a leak.Good to lock ring in place with a hoseclamp.

[sailorboy1]

the bellows is pretty tight aganist the collar

I'm not going to try move that collar anyway while in the water, sounds like a way to sink!

[Blue Stocking]

With the head pressure on the incoming water being only about 1 pound, you should easily stop this with a towel around the shaft.
But do what you feel safe with.

[Noname]

Did you or someone remember to "burp" the bellows when you launched this spring?

[senormechanico]

Don,

If it's a PYI seal, there are allen screws which need to be taken all the way out, then loosen the allen screws underneath the ones you removed.
Slide the collar a bit closer to the bellows.
Tighten allen screws and reinsert the other ones to lock the inner ones in place.

I once changed a bellows while we were in the water, but as I had to lie on the engine and halfway stand on my head, it took some time for me to work up the courage to do it !

[Target9000]

Originally Posted by senormechanico

Don,

If it's a PYI seal, there are allen screws which need to be taken all the way out, then loosen the allen screws underneath the ones you removed.
Slide the collar a bit closer to the bellows.
Tighten allen screws and reinsert the other ones to lock the inner ones in place.

I once changed a bellows while we were in the water, but as I had to lie on the engine and halfway stand on my head, it took some time for me to work up the courage to do it !

As I recall...

If you loosen those set screws for any reason, even just to move the collar, they must be replaced completely. They are one time use.

I could just be remembering wrong but I'd check on it.

[Noname]

Don,
In case you want to do a little research on the subject, their website covers all the bases:
PSS Shaft Seal

[senormechanico]

Originally Posted by Target9000

As I recall...

If you loosen those set screws for any reason, even just to move the collar, they must be replaced completely. They are one time use.

I could just be remembering wrong but I'd check on it.

They say that, but imho, it's CYA.

From their instructions:
http://www.shaftseal.com/en/about/in...n_instructions

"Do not re-use the supplied cupped pointed sets screws.If multiple tightening has flattened the cupped-point set screw,replace the affected screw with a new one."



(The key is "If multiple tightening has flattened...)

[sailorboy1]

Guess I'll just try and flood the boat next weekend pushing the seal away and try to wipe down the faces.

[Noname]

Originally Posted by Don Lucas

Guess I'll just try and flood the boat next weekend pushing the seal away and try to wipe down the faces.

Don't use any oil.

[senormechanico]

Don,
If it doesn't leak when stopped, try low speed forward.
If it only leaks under heavy throttle in forward, you only need to move the collar aft a bit, maybe a quarter inch max.
Also, check your motor mounts for excessive fore/aft play. Yanmar?

[delmarrey]

Originally Posted by Don Lucas

Guess I'll just try and flood the boat next weekend pushing the seal away and try to wipe down the faces.

I've changed these out while in the water. Just keep some rags handy to slow the water, and prepare before the operation. Think ahead. There's not that much water pressure. If the water's warm enough you can dive down and stuff rags in the stern tube.

Up to 1-1/4" shafts the bellows needs to be loaded 3/4";

12. Slide the stainless steel rotor down the shaft until it just TOUCHES the carbon. Mark this position on the shaft as the “neutral” position with a marker or a piece of tape on the shaft just in front of the rotor.

13. Sliding the stainless steel rotor aft,compress the bellow by the amount indicated on the bellow compression chart ,using the “neutral” mark as a reference point..While keeping the bellow in the “compressed” position, tighten the two (2)set screws against the shaft with the provided allen wrench.

There a a few things that will make the seal leak;
Load on bellows not enough.
Carbon ring is damaged/worn.
Shaft is vibrating/whipping.
Bellows is out of alignment (needs to be on center). Loosen clamps at stern tube and readjust.

BTW PYI now sells a clamp collar to go behind the seal ring but a hose clamp will work, just tackie.