Thursday, December 14, 2023

Replacing the Prop Shaft Seal

Replacing the Shaft Seal on our Prop shaft

While searching a the water leak ( turned out it was from the hot water tank ) I noticed that the PSS Shaft Seal was showing it's age. The boat was out of the water, we're delayed from splashing for a few days to the weather so I bit the bullet and ordered a replacement shaft seal.

 This is what the new one looks like ( currently shipping NDA from Defender ) $302 = $352.05 inc. Shipping & Tax.

The currently installed Packless Shaft Seal - PSS does not have the barbed water fitting which ensures that the inside of the fitting is water lubricated.

I looked up the size in the Catalina 34 Owners Manual. The shaft is 1" and the shaft log in 1 5/8" OD 

The PSS part number is 02-100-112

The total cost from Defender was about the same as just the pre-tax cost from WM. 

The Old Packless Shaft Seal 

That photo shows the Prop Shaft, the Packless Shaft Seal ( PSS ) and the flange that connects the Prop Shaft to the Gearbox. 
Note the black line on the below the PSS, it extends 360ยบ around the inside of the hull and under the deck of the aft cabin. That's splatter from the old PSS! Basically the PSS is failing ( it's at least 8 years old). The sealing surface between the flat surfaces of the rotating stainless-steel rotor and the stationary carbon flange eventually wear and then the seal fails, it's not a sudden catastrophic failure, it just wears out.  PYI ( Manufacturers of the PSS ) state a 6 year maintenance schedule. Ours is at least 8 years old!

Step 1. Remove the hose clamps.

There are Four clamps, two hold the aft end of the bellows to the shaft log and two hold the bellows to the carbon 'Stator'  

The old clamps were of the perforated type, so they went straight into the garbage.

Next I removed the two set screws from the Shaft coupling, I figured that it would be easier to remove them before separating the flange from the gear box drive flange.  It was, but it was not easy! The set screws had Square ends rather than hexagonals, so the only tool I had that would grab them enough to allow unscrewing them was a 14" Pipe Wrench.  There's not that much room down there and access is for really small people! It took nearly and hour just to remove those two set screws.
Once they were out, the connection to the gear box was easy.

Getting the coupling off of the prop shaft was not pretty! There was not enough room for me to use my three leg puller between the end of the shaft and the gear box, so I had to resort to applying a Sudden High Impact Tool - Hammer! striking the aft end of the coupling. That took another half hour. It finally came off and I was able to remove the shaft Key.

I cut the bellows, removed the 4 set screws from the Stainless Steel Rotor of the PSS and was able to pull the rotor off of the front end of the shaft.

Time for a clean up. Basically I used Soap liquid to wash down the whole area and lots of shop paper towels. 

Preparing the shaft for the new PSS involved sanding it with wet-n-dry paper. I stared with 80 Grit to take off the edges of the key slot and the concave dimples where the two set screws grab the shaft and to ease off the dings caused by my heavy hammering getting the coupling off.  Then it was more sanding using 220, 600, 1500 and finally 2000 grit W&D paper.  

I tested the fit of the SS rotor by using the old one, a light film of dish liquid on the shaft and the O-rings of the old rotor and it slid nice and easy over the shaft, not catching anything.

Next I cleaned the outer surface of the shaft log, just a couple of minutes with 220 grit paper and a washdown with soapy water. 

Now everything was clean and smooth. I scrubbed my hands to ensure I didn't get any contaminates onto the shaft or the new PSS. 

Easing the two aft hose clamps on the new PSS Bellows, I slid the bellows onto the shaft log. PYI advise not to push the bellows to far onto the shaft log however, the build the shaft log does not allow for the bellows to go that far, so no issues there. 

I rotated the PSS bellows so that the hose barb on the forward edge of the bellows pointed upwards. Then I tightened the clamps around the bellows at the shaft log end.

Wiping down the face of the carbon Stator and the Stainless Rotor, and then applied soap liquid to the shaft and the inside of the new Rotor. The new rotor fit nicely over the smooth prop shaft and was slid down to the Stator end of the PSS.

I cleaned up the Shaft to Gearbox coupling and slid that over the end of the Prop shaft ensuring the key was correctly positioned.  

The old bolts from the coupling were showing signs of thread damage, I purchased four new nuts and bolts and spring washers. I used the new bolts to attach the coupling to the gearbox tightening them just enough to make a snug fit, I'll check the alignment when the installation is complete.

With the coupling installed, I gently tapped the end of the prop shaft from the outside to get it fully inserted into the coupling, mindful of the fact that it applies pressure to the gearbox.  With the shaft now correctly positioned, I installed the new set bolts. ( I had also purchased new bolts to replace the square ended screws) to secure the coupling to the shaft.

Now that the shaft was in it's correct position, I moved the Stainless Rotor aft to touch the Carbon Stator and measured from the front edge of the Stainless Rotor to the aft edge of the bellows = 7 1/16".
With the set screws inserted into the Stainless Rotor but not touching the shaft, I compress the bellows by pushing back on the rotor until the distance changed from 7 1/16" to 6 5/16" = a compression of 3/4" as prescribed. 

All done except for the ventilation hose. I stopped by ACE hardware and picked up about 12' of 3/8" ID reinforced hose. I have clamps on the boat. 

Hose installed at the PSS and ran back below the Aft water tank then up to the Stbd side under the combing. No loops in the hose in order to prevent syphon back down the hose.

The hose is zip tied to the existing hoses that run from the aft locker and tank area to the under sink area.  Getting into the aft locker is getting more difficult, I'll have to practice some more boat yoga.

I also checked the Alignment, less than 4 thou" pretty darned good.

The boat is ready to splash on Tuesday 19th of December.  

See you 'on top' of the water.


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