Cabo dripless shaft seals

CSkipR · 03-13-2010, 10:31 AM

On my Cabo the starboard dripless seal housing around the shaft seems to wobble on the shaft whereas the port stays still. What might cause this and is it of any concern. Its not wobbling alot but is moving. Pretty sure the shaft is straight so don't think thats the problem. thanks, skip

Marmot · 03-13-2010, 10:46 AM

Quote:

Originally Posted by CSkipR

What might cause this and is it of any concern.

If the shaft is not bent and the seal is not leaking the only thing it can be is the rotor is cocked on the shaft.

Can you use a dial indicator and check the shaft and rotor for radial and axial position as the shaft rotates?

This isn't the end of the world yet, but it is a warning.

CSkipR · 03-13-2010, 10:52 AM

Quote:

Originally Posted by Marmot

If the shaft is not bent and the seal is not leaking the only thing it can be is the rotor is cocked on the shaft.

Can you use a dial indicator and check the shaft and rotor for radial and axial position as the shaft rotates?

This isn't the end of the world yet, but it is a warning.

Marmot,
Thanks for the reply. We did put a dial indicator on the shaft and its out about 3 thousands but that could also be the couplers not quite a perfect fit. When I pull the boat this week will check the shaft right where it exits the boat.

Marmot · 03-13-2010, 11:01 AM

Quote:

Originally Posted by CSkipR

Marmot,
Thanks for the reply. We did put a dial indicator on the shaft and its out about 3 thousands but that could also be the couplers not quite a perfect fit. When I pull the boat this week will check the shaft right where it exits the boat.

Check the shaft seal rotor on its circumference and along the forward face to see if it is cocked or is displaced radially. Even if the shaft is perfect, anything that causes the rotor to sit crooked will make the whole seal wobble. Is the rotor the correct size for the shaft?

CSkipR · 03-13-2010, 11:04 AM

Quote:

Originally Posted by Marmot

Check the shaft seal rotor on its circumference and along the forward face to see if it is cocked or is displaced radially. Even if the shaft is perfect, anything that causes the rotor to sit crooked will make the whole seal wobble. Is the rotor the correct size for the shaft?

How do you check the rotor to see if it is cocked. Do I take the shaft seal apart? I'm sure the rotor is the correct size since the other side is fine.

Marmot · 03-13-2010, 11:17 AM

Quote:

Originally Posted by CSkipR

How do you check the rotor to see if it is cocked. Do I take the shaft seal apart? I'm sure the rotor is the correct size since the other side is fine.

The rotor is the stainless steel part that is fastened to the shaft with set screws. Secure your dial indicator on some part of the hull and zero it out on the outer rim of the rotor and turn the shaft by hand. That will give you a radial runout and show if the shaft is bent or the rotor is not centered on the shaft.

If it does show a large displacement, zero the indicator on the shaft just forward of the rotor and see if it indicates the same displacement. If it does, your shaft is bent, if it does not your rotor is incorrectly aligned.

If the indicator shows no problems above, zero the indicator on the front face of the rotor and turn the shaft by hand. That will show you if the rotor is sitting at an angle to the shaft centerline, i.e. if it is cocked or displaced axially. This is most likely the cause of a wobble if the shaft is not bent or out of alignment. There are several reasons the rotor could be displaced, too large a bore, junk between the rotor and shaft when it was installed, bore not 90 degrees to face ... that's why manufacturers hire QC techs.

In any event, make sure you let us know what you find. I am sure you aren't the first or only person to see this and your findings add to the database here. Good luck, hope it is something simple.

Capt J · 03-13-2010, 12:18 PM

I have also seen Tideseal brands (which have a very very hard plastic/rubber) that rides on the shaft eat 30 thousands out of the shaft where it rides on it and cause the entire assembly to wobble and then eventually it started leaking. The shafts on this boat were only 1.5" and we replaced the shaft, as well as the tideseal, because there was too much clearance for the new seal to seal, and we were worried about strength as well.

Marmot · 03-13-2010, 02:06 PM

Quote:

Originally Posted by Capt J

I have also seen Tideseal brands ...

Good point J. I (maybe incorrectly) just assumed it was a PSS seal.

CSkipR · 03-13-2010, 07:36 PM

Not sure what kind of seal it is but its not a PSS. What does Cabo normally install?

Marmot · 03-13-2010, 10:03 PM

Quote:

Originally Posted by CSkipR

Not sure what kind of seal it is but its not a PSS. What does Cabo normally install?

Can you post a picture? I have read reviews where they have a proprietary seal but dripless seals are mechanical seals so will have a rotor and a stationary face.

Look up the installation drawing for a PSS seal and see if yours resembles theirs. If so then the dial test procedure is still applicable.

K1W1 · 03-14-2010, 03:33 AM

Hi,

Does it look like this?

http://www.tidesmarine.com/nostrong.html

or this

http://www.shaftseal.com/system/prod...gif?1235420156

CSkipR · 03-14-2010, 08:22 PM

Quote:

Originally Posted by K1W1

Hi,

Does it look like this?

http://www.tidesmarine.com/nostrong.html

or this

http://www.shaftseal.com/system/prod...gif?1235420156

Number 2 shaft seal

Capt J · 03-14-2010, 08:32 PM

Quote:

Originally Posted by CSkipR

Not sure what kind of seal it is but its not a PSS. What does Cabo normally install?

Call Cabo with your hull number and speak to the parts department and they can look up exactly what system your hull has. They'll also have the seals and such......they've switched over the years.....is it a bronze body?

CSkipR · 03-14-2010, 08:33 PM

Quote:

Originally Posted by Capt J

Call Cabo with your hull number and speak to the parts department and they can look up exactly what system your hull has. They'll also have the seals and such......they've switched over the years.....is it a bronze body?

Capt J it does have a bronze body.

Marmot · 03-14-2010, 10:49 PM

Quote:

Originally Posted by CSkipR

Capt J it does have a bronze body.

What part are you calling the body?

If it looks like the second link K1W1 provided, it is a PSS style. The rotor is on the right side of that drawing, it is secured to the shaft. The corrugated looking bit on the left is rubber or plastic and connects to the log. The intermediate part with the tubing barb sticking up is the stationary part of the seal.

The instructions for checking with an indicator apply to the seal shown in the second link.

Do you by any chance have a standard packing gland that is mounted forward of the log by a length of stiff rubber hose and not a mechanical (dripless) seal?

Or is it maybe one of those "bluewater" things that has a lip seal inside a housing that looks like a standard stuffing box connected to the log by a short piece of rubber hose?

If it is one of the latter, your shaft is either bent or it's whipping and the lip seal won't last long either.