PSS shaft seal operating temperature

Sep 19, 2018
12
Mirage 33 St. Clair Shores
I recently installed a PSS shaft seal in my 1982 Mirage 33 with a Yanmar 3 GMD. This is my first time having the boat in the water with the seal installed. When the boat was first launched I motored for about 15 min went down and checked it and it was really hot. I called the company and was asked a few questions and told to burp it. After that it did help but still felt warmer than I expected. I went out again this time with a infrared temp sensor and found the temperatures ranging between 90 degrees to 105 degrees Fahrenheit on both the carbon stator and the stainless steel rotor. According to PSS anything upto 100 degrees is within safe operating range I'm curious what others have experienced.
 

Attachments

Feb 14, 2014
7,399
Hunter 430 Waveland, MS
You must keep a water film, to reduce friction, between stator/rotor mating surface.
How is your seal purged hooked up?

and told to burp it
It should not need "Burping" if your purge is done correctly.

The act of going from Reverse to Forward several times... "Burps" the air entrapped in your bellow.

IMO, the shaft alignment is more critical than "burping"

Jim...
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
Your vent tube, depending on how its installed, may or may not spit water when the boat is in reverse. If there is not clean air flow, water cannot get up the shaft to the mating surfaces, and from what the post suggests, thats not happening.
Simply running the boat in reverse may, or more likely may not get all the air out. The pss will not get hot, in fact, in a sailboat, not even warm.
You need water at the mating surfaces, and if not, you will likely destroy the carbon ring in short order.
 
Sep 19, 2018
12
Mirage 33 St. Clair Shores
So my vent tube is just run above my fuel filter assembly just barely cut of in the picture. When I lowered the vent hose below the water line water came out. Shaft alignment was checked when I reassembled it after installing the dripless seal but the boat was out of the water for a year so it could be off. I was under the impression the new design didn't need to be purged so after it launched I thought air being trapped wasn't an issue.
 
Feb 14, 2014
7,399
Hunter 430 Waveland, MS
When I lowered the vent hose below the water line water came out.
Then your bellow is full of water.:)

The water back flows between the mating surfaces.

If you put your engine in full reverse, you should see a "squirt" of water from the purge hose.
Not so much if more than a foot above your boat's water line.
Jim...
 
Dec 28, 2015
1,837
Laser, Hunter H30 Cherubini Tacoma
Interesting. I installed one of these on my ski boat probably 15 years ago and the directions stated the hose coming off the collar was installed into the cooling system which forced water reverse through the coupler. You confirmed water slow and amount by pushing graphite collar back from the mating surface allowing water into the bilge.
 

BillyK

.
Jan 24, 2010
502
Catalina 310 Ocean City, NJ
it looks like your bellows is very compressed. did you compress it more than what PSS recommends? it might be pushing too hard against the collar causing too much friction.
 
Sep 19, 2018
12
Mirage 33 St. Clair Shores
I was very careful with getting the compression right did it according to the instructions even made a collar to fit over the shaft cut to the right size. I thought the same thing and looked at pictures of other installations and they to showed a lot of compression as well. Also when I removed the shaft I had it checked for straightness and there is a brand new Campbell Sailor 3 blade prop. It runs really smooth very little vibration.
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
there's yet another thing, it will take a "while" for the surfaces to fully mate, and the carbon face will wear a bit in the process. Since we agree that the vent is proper, and there's no air in there, as stated just above, the compression is right, then the only thing left, assuming there isn't some salad wedged in there, the only thing left is settling into place.
Look closely at this picture, and the trunk on the other side. See the vertical black line? That's carbon getting thrown off the ring as it settles into place. If you clean that off, take the boat out for a spin, various rpm's for, say 20 minutes, then go clean it off again, wash wax repeat. Every cycle will show less carbon, and in 1/2 hour or so, there will be none. The faces are seated.

(and unless something is really wrong, it'll be stone cold)

IMG_0402.JPG

and yes, mine is the old style with the nylon nipple and the boat is going straight to the bottom, and this thing is 8 years old and still floats just fine, so I don't want to hear about it. :)
 
Sep 19, 2018
12
Mirage 33 St. Clair Shores
Stone cold is what I was expecting. I hope you are right about it needing to break in. I know every boat is different and the amount of water circulating won't always be the same. 105 degrees isn't by any means hot for the seal but doesn't instill a lot of confidence in it for me if it is operating on the high side and what's the warning if it gets hotter like it did?
 
Jul 26, 2009
291
. . .
Nice bilge and good looking install.

I need to burp ours at the beginning of each season after storing on the hard. I burp it longer than I think necessarey to ensure all air is evacuated.

I did feel it get hotter than usual once before after normal use. I burped it on that occasion which addressed the issue. Normally it is relatively cool to the touch while motoring.
 
  • Like
Likes: Meriachee
Sep 19, 2018
12
Mirage 33 St. Clair Shores
Thanks I took my time, that's one thing on my boat I really don't want to fail. That makes me feel better knowing that they can get warmer I will keep an eye on it for awhile to make sure it doesn't get any hotter or hopefully cools down a bit.
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
Should be fine. I was told no end of doom and gloom and how the boat was going straight to the bottom. The only thing thats a bit of a downside on the little Catalina is no place to run the breather line. So now and then when doing a burnout in reverse, we get a little motor washing action.
(And then i take the cover off to check the oil and have a poop over a cup of water in the engine bay)

I put a brass bolt in the end of the breather line with a 3/16 hole drilled through it. Lets water out, but not a lot. Not recommended so do this at your own risk.
 
Feb 14, 2014
7,399
Hunter 430 Waveland, MS
I purge mine with my sea water pump, since i had no room for the vent.
My last point about alignment

Are your motor mounts in good condition?

Thrusting will move your engine on those mounts.
Jim...
 
Sep 19, 2018
12
Mirage 33 St. Clair Shores
The motor mounts if I had to guess are original. No visible signs of damage or cracks but probably are due to be replaced. That would probably be a good thing for me to look into to.
 
  • Helpful
Likes: JamesG161
Feb 14, 2014
7,399
Hunter 430 Waveland, MS
No visible signs of damage or cracks but probably are due to be replaced
You would have to observe the mounts when doing a full forward thrust.

Stiff ones won't budge, thus adding a bending moment [stress] to your shaft alignment.

Do a full Reverse also. Why?
Most of our engine time is in Forward.

But...

It sounds like forward would suffice to verify.
Jim...
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
I don't see how shaft alignment deviations would cause excessive heat in the pss. Yes the shaft can move, but the only component that would see the deviation would be the bellows and its designed to do that. Am I missing something?
 
Feb 14, 2014
7,399
Hunter 430 Waveland, MS
Am I missing something?
well yes

Any misalignment would force the mechanical seal to an angle, when thrusting.

That is the reason they use Shims to align a shaft.

The engine mounts give enough to maintain a good alignment.

Ok I did my best to add to the Friction heat discussion.:cool:
Jim...
 
Feb 14, 2014
7,399
Hunter 430 Waveland, MS
The Bellow functions as the spring, to push the mechanical seal to a close tolerance.
and..
Prevents water from flooding your boat.

It does not compensate for any misalignment.

It is not a flex joint.

Jim...
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
I'm not sure I agree. The stainless ring is fixed to the shaft. The graphite plug floats on the shaft. If there's enough wobble going on that parts that far, ah, downstream are moving against each other enough to generate heat in a cooled environment, then that engine would be shaking the boat something severe.

My little Westerbeke will shake a drink off the table it vibrates so bad, and the pss is stone cold.