PSS shaft seals leaking when throttling up

[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.

[chris mac]

Can't seem to attach a video

[gs41escapade]

I replaced the packing gland on prior boat with PSS seal. I believe the initial spurt is normal. You should not get any continuous leakage underway either sailing or under power.

[senormechanico]

The bellows gets tired after awhile. I just squeezed ttuhe collar a bit tighter and it didn't leak. I eventually replaced the bellows.
Think of it as a consumable item.
I even replaced it with the boat in the water. Bilge pump pretty much kept up with the inflow.

[mikereed100]

The bellows lose resiliency over time. Just push it in a bit more. PSS recommends replacing the bellows every 6 years.

[Windpilot]

I've got a new pss shaftseal now for a month and I've noticed a tiny bit of water (tablespoon) now and then. Idk what to make of it, installed by a very reputable yard.

[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.

[noelex 77]

The PSS seal should not leak at any time. The only exception is when it is brand new. It sometimes takes a little while for carbon seal to bed down to the right shape.

[wrwakefield]

Did you witness mark the shaft [e.g., indellible pen mark on shaft at forward edge of collar] when you finished the original installation to help determine if the compression collar moved? Or install a back-up collar outside the SS compression collar?

Adding some additional compression will likely solve the issue as long as the graphite collar face isn't buggered up.

I just finished replying on a similar thread that includes some hints, techniques, and photos you might be interested in.

Cheers, Bill

[gs41escapade]

Originally Posted by noelex 77

The PSS seal should not leak at any time. The only exception is when it is brand new. It sometimes takes a little while for carbon seal to bed down to the right shape.

That may be what I noticed at first - that first squirt. After not having leakage from the old packing gland, I stopped inspecting so often.

[Scubaseas]

How are your motor mounts? How much does the engine move when you put it in gear and rev it? Should be near zero. if you notice movement you may have a worn or broken mount. There should be zero leakage on a PSS after the carbon is worn in. If the boot is too loose it can leak but if it's been "burped" there really should not be any kind of leak.

[chris mac]

Seals are 6 months old, mounts were brand new same time. Alignment is very good, in terms of lack of vibration.
Shaft does move forward or back slightly as it engages forward and reverse. That's what seems to engage the leak. When the shaft engages forward, the bellows stretch slightly and a leak happens. It seems to only be a strong acceleration issue.
That makes me think tightening then by 1/8- 1/4" would be good. But this isn't something I've worked with before.
Oh, and this is a v drive, if that makes any difference. It sure does for accessing the set screws[emoji35]

[Scubaseas]

Originally Posted by chris mac

Seals are 6 months old, mounts were brand new same time. Alignment is very good, in terms of lack of vibration.
Shaft does move forward or back slightly as it engages forward and reverse. That's what seems to engage the leak. When the shaft engages forward, the bellows stretch slightly and a leak happens. It seems to only be a strong acceleration issue.
That makes me think tightening then by 1/8- 1/4" would be good. But this isn't something I've worked with before.
Oh, and this is a v drive, if that makes any difference. It sure does for accessing the set screws[emoji35]

I've worked with quite a few. First make sure the faces of the carbon and the stainless disc are clean. Do not grease the faces. Wipe both wear faces with a lint free cloth or shop towel. Compress the boot another 3/8" to 1/2". Depending on the shaft size you should have contact then compress 1/2" to 3/4" or more for bigger shafts. If you have room add a collar zinc to the shaft to make sure the stainless ring stays in place. It may take a few minutes (15 to 30 minutes) to let the seal wear in and there may be a small leak but after that it shouldn't leak at all. You may get some dust when it first wears in. Make sure to pull the ceramic/boot back from the stainless collar to burp out the air under the bellows.

Eyeball the carbon/ceramic. If it's got gouges you can fix it by wet sanding the carbon flat on a glass plate or on a known flat steel plate with 180 to 220 wet/dry grit initially then down to 400 grit wet/dry. Use lots of water. If you want, you can use toilet bowl wax or towels stuffed into the shaft tunnel or log to slow the incoming water down but with decent bilge pumps the incoming water should be manageable leak.

[skipperpete]

About the vee drive, yes, it does change the relationship with the propeller shaft depending on the installation. If its an island mounted Walter drive it could move forward against the mounting blocks enough to allow the PSS to leak.
Is this happening to only one engine or both in a twin installation?

[Mickeyrouse]

Flexible mounts do just that- flex. If your collar is not adjusted properly against the bellows, forward motion can create a gap. It’s possible that this along with slightly loose set screws on the collar can allow just enough gap to leak water while under way. Loosen the set screws then move the collar back, usually 1/8” should do it. Usually awkward to get to. Then re-tighten both set screws securely. I replaced the set screws on my collar with 1/4” hex head machine screws- it’s much easier to get a tool on it, and you can torque the screw a little higher. I recommend not using stainless here- this is an awkward place to twist the head off a relatively soft stainless machine screw. Put Never Seize or equivalent on the threads to prevent that screw from becoming permanent.