PSS seal machining faces

[Tom Hildebrandt]

I have a PSS seal which is not leaking but both the faces have minor grooving. Has anyone had experience machinging the faces on these units?

[NoTies]

Leave the carbon stator alone but it is possible to machine the stainless rotor. Better to wet grind if that is an option rather than use a cutting tool. Alternatively you can turn it around and use the front face if it free of damage.

[AnchorageGuy]

Tom, If it ain't broke, don't fix it. Chuck

[NoTies]

Do fix it as the grooving can hold abrasive particles that will accelerate the wear between the two faces. Do you wait for your fuel filters to clog before changing them?

[dandrews]

Asking a question on this thread.... Working on a project boat that came with tons of misc. items, one being a PSS. My quest is should the ID of the carbon section be the same size as the shaft and the ID of the SS portion? The one I have the ID of the carbon is larger than the shaft. Thanks for any comments.

Don

[AnchorageGuy]

Don, They should be exactly the same. Tom, I have installed hundreds of these dripless systems, including our own current boat. You can mess up the seal between two surfaces if your not careful. Since it's not leaking and to remove and work on the system, the boat has to be hauled, I would make a call to PYI and get their input before doing anything. They can give you the straight answer since they make the system. I have always found them to be open and honest whenever I had a question. Chuck

[dandrews]

Thanks Chuck. My own thoughts were that they should be the same. Boat is on the hard in my side yard so I can get things right before it ever see water. Installing new shaft, completely rebuilt 3GM, etc. I will call the PYI folks and chat with them.

Don

[NoTies]

As I have said on this forum before, mis-information is dangerous. If you need to ask then ask the manufacturers. Some comments made here are false.

[delmarrey]

It's a no-brainer!!!
I've done it. It only took about .005" to clean up each side. It's best to machine rather then hone so as to get it square with the shaft/hole. As long as the thickness stays away from the internal O-ring groves all is well.

The carbon can be lapped with a wood block and sandpaper. It's self aligning.

[NoTies]

Originally Posted by delmarrey

It's a no-brainer!!!
I've done it. It only took about .005" to clean up each side. It's best to machine rather then hone so as to get it square with the shaft/hole. As long as the thickness stays away from the internal O-ring groves all is well.

The carbon can be lapped with a wood block and sandpaper. It's self aligning.

Wet grinding with the appropriate attachment on a lathe is good but if using a cutting tool make sure the slowest possible cross slide feed speed is used.
The stator has a larger ID than the rotor to allow it to float on the seal face and get rid of the lubricating water rather than forcing the rotor and stator apart to release the water.
Replacing these seals in the water is entirely possible with proper preparation and saves a huge amount of time and money. It is very difficult to haul vessels here so we do everything we can in the water. Last week a 2" PSS replaced in the water in 3 hours. It would have taken longer just to haul a boat here and cost around $900.

[Celestialsailor]

Originally Posted by NoTies

Wet grinding with the appropriate attachment on a lathe is good but if using a cutting tool make sure the slowest possible cross slide feed speed is used.
The stator has a larger ID than the rotor to allow it to float on the seal face and get rid of the lubricating water rather than forcing the rotor and stator apart to release the water.
Replacing these seals in the water is entirely possible with proper preparation and saves a huge amount of time and money. It is very difficult to haul vessels here so we do everything we can in the water. Last week a 2" PSS replaced in the water in 3 hours. It would have taken longer just to haul a boat here and cost around $900.

I shoot people in shops who put a grinding attachment on a nice lathe. Best to turn it on a lathe after indicating it's parallel surface. Yes, slow feed but best to drag the tool (carbide) from the ID to the outside for finish.

[cal40john]

Originally Posted by dandrews

Asking a question on this thread.... Working on a project boat that came with tons of misc. items, one being a PSS. My quest is should the ID of the carbon section be the same size as the shaft and the ID of the SS portion? The one I have the ID of the carbon is larger than the shaft. Thanks for any comments.

Don

Originally Posted by Waterwayguy

Don, They should be exactly the same. Tom, I have installed hundreds of these dripless systems, including our own current boat. You can mess up the seal between two surfaces if your not careful. Since it's not leaking and to remove and work on the system, the boat has to be hauled, I would make a call to PYI and get their input before doing anything. They can give you the straight answer since they make the system. I have always found them to be open and honest whenever I had a question. Chuck

Interesting I've only worked on the one on my boat, the I.D. of the carbon ring is not the same as the stainless donut, it is bigger. If it were the same size it would only be a few thousandths bigger than the shaft (whatever allowance needed for the o-ring compression in the donut) and have no play to self align and seems a good way for it to potentially bind on the shaft and tear the bellows out. PYI didn't say anything was wrong with mine when I drove up there with the entire PSS to be refurbished with propeller and shaft as I needed the Max-Prop tuned up as well.

[NoTies]

Originally Posted by Celestialsailor

I shoot people in shops who put a grinding attachment on a nice lathe. Best to turn it on a lathe after indicating it's parallel surface. Yes, slow feed but best to drag the tool (carbide) from the ID to the outside for finish.

Wet grinding as I specified is a lot better. I used to work on a ship that had the lathe and dry grinding attachment for valve refacing 4' from the main engine turbo inlet and upwind.

[AnchorageGuy]

Originally Posted by cal40john

Interesting I've only worked on the one on my boat, the I.D. of the carbon ring is not the same as the stainless donut, it is bigger. If it were the same size it would only be a few thousandths bigger than the shaft (whatever allowance needed for the o-ring compression in the donut) and have no play to self align and seems a good way for it to potentially bind on the shaft and tear the bellows out. PYI didn't say anything was wrong with mine when I drove up there with the entire PSS to be refurbished with propeller and shaft as I needed the Max-Prop tuned up as well.

Your absolutely right, I don't know what I was thinking when Don said I.D. The carbon ring is larger. For Don the number for PYI is 800-523-7558. Chuck

[aboutgone]

A piece of glass and water based valve grinding compound ... That's what I use here at the boat yard. Works great and faster than you think !!!