PSS Failure on only one shaft

[juliogustav]

We have had a couple of PSS failures due to the front stainless steel ring sliding forward and causing alot of water to come in. More than my bilge could keep up with. I have 1) slid the ring back, put new lock screws in and added a hose clamp. It failed again. 2)I have replaced the engine mounts, pulled and checked shaft alignment, changed out the PSS adding a hose clamp. I thought all was good.
Recently we ran of some old nylon rope, about 3/4 inch. It stalled out the engine. I jumped in and freed the line from the shaft and noticed how tight it was on the shaft/strut face. When i pulled real hard, a small open space appeared on the shaft, this distance immediately slid back into the boat. When I climbed onboard the bilge alarm was on. Stainless ring on PSS had slid forward causing a large amount of water to come in. Ugh!! 3) I have now added a stainless steel collar instead of the house clamp.

The question - do you think this is bad luck. We have never had a problem in the last 10 years with the port side. The cat dose have three blade folding props. Help

[phorvati]

Post pics of your set screws and rotor. Those have to bite and I am wondering if they are biting into fresh shaft.

[juliogustav]

Will do but its hard to get a good pic, not much room. I did tighten screws to the point that screw or allen wrench was about to strip.

[skipperpete]

Hey JulioGustav, firstly, welcome to the forum. There should be no circumstance where you can pull back on the propshaft unless you have a little engine with really soft mounts (or a flexible shaft coupling that’s let go). You might have just found the reason for your previous PSS failures, good as they are, they won’t tolerate much shaft movement fore and aft. Put yet another hose clamp on the propshaft and re set the preload till you can ( carefully and quickly) get to where you’re able to more thoroughly investigate the problem.
In answer to your question...... NO, bad luck is not the cause of the PSS seal problem, it’s something that you aren’t noticing about the way your propshaft,propeller and engine is interacting with that PSS. ( which by the way is a pretty good seal)

[juliogustav]

It would seem that the engine mounts might have given the play. I did have my feet against the hull and pulled, un spooled the line, with all my might. The engine mounts are 3 year old Yanmar made.

[Marathon1150]

Two comments.

We recently replaced the billows on our PSS shaft sea, apparently this should be done every 5 or 6 years but it took us nearly 10 to get around to it. The billows replacement kit from PSS contains new set screws and the instructions are very clear that the old set screws must not be reused. So we didn't.

Not long after we installed the PSS to replace a Volvo dripless seal, we met the owner of PSS at the Toronto boat show. I tried to buy the PSS version of the shaft clamp that should make it impossible for the stainless ring to move up the shaft and his response was 'use a high quality hose clamp'.

We have never had a problem with our seal. You may want to consider:
- getting new set screws
- putting two high quality AWAB hose clamps on the shaft.

[NorthCoastJoe]

Always use new set screws and a high quality allen wrench. They make a pro version that includes a collar to back up the rotor. I have that version now with no problems. We have had no movement. Our old set screws were so tight I had to drill them out with left hand drill bits.

[Kd9truck]

Ok what is PSS ?

[Hobby]

Here you go

https://www.westmarine.com/on/demand...al-catalog.pdf

[rslifkin]

Regardless of the PSS issue, if the seal separating is more than your bilge pumps can keep up with then you desperately need to upgrade your bilge pump setup. The factory install on many boats is nowhere close to adequate.

[Kd9truck]

Originally Posted by Hobby

Here you go

https://www.westmarine.com/on/demand...al-catalog.pdf

Thanks

[juliogustav]

Thank you all for the response. I believe the issue might be the engine mounts. They had been replaced 3 years ago, but maybe with the folding prop, v-drive, length of shaft, strut placement, and folding prop, there is just to much opportunity for the shaft to move. Something is causing the pss to push apart. An no one has mentioned water pressure of why one side would be an issue. Give me a few months and I will get back with you. As for a pump. I have two submersible pumps. A PSS failure can create quite a bit of water coming into your boat. New PSS, setscrews, shaft coaler, good allen wrench have all been used. Thanks

[Pegu Club]

Originally Posted by skipperpete

Hey JulioGustav, firstly, welcome to the forum. There should be no circumstance where you can pull back on the propshaft unless you have a little engine with really soft mounts (or a flexible shaft coupling that’s let go). You might have just found the reason for your previous PSS failures, good as they are, they won’t tolerate much shaft movement fore and aft. Put yet another hose clamp on the propshaft and re set the preload till you can ( carefully and quickly) get to where you’re able to more thoroughly investigate the problem.
In answer to your question...... NO, bad luck is not the cause of the PSS seal problem, it’s something that you aren’t noticing about the way your propshaft,propeller and engine is interacting with that PSS. ( which by the way is a pretty good seal)

This post has the right info, and leads you in the correct direction, we have had a PSS shaft seal for six years, without any issues, I recently replaced the bellows as preventative maintenance while we were on the hard In Cambridge Md, (currently in Beaufort NC heading to the Bahamas) the install is straightforward and not so difficult. Hope you get this resolved in a timely manner,

[juliogustav]

Agreed

[skipperpete]

Juliogustav, the Vee drive might be the cause of your woes, a conventional straight drive gearbox pushes in a different way to a Vee drive which actually tends to lift the rear of the engine up a little under full power. A straight drive tries to push all 4 mounts forward at the same time, harder mounts might be the answer, particularly if your new Yanmar mounts are the very squidgy 3GM type.