SailNet Community

SailNet Community (http://www.sailnet.com/forums/)
-   Gear & Maintenance (http://www.sailnet.com/forums/gear-maintenance/)
-   -   Help with packing problem (http://www.sailnet.com/forums/gear-maintenance/67226-help-packing-problem.html)

stevemac00 08-11-2010 07:04 AM

Help with packing problem
 
http://i208.photobucket.com/albums/b...0/IMG_3667.jpg
I'm getting ready to motor out the Erie Canal so I changed the packing. I didn't know the size and used 3/16 but it didn't quite fill the gap between the nut and shaft so I cut one the size of the nut and another the size of the shaft so they'ed fill the gap. The drip rate is controlled correctly but now I have some bronze dust in the bilge drain as shown in photo.

Looking for suggestions as what is causing this and what I should do to stop it. I used syntek PTFE and lube. I have some more with me so I could change it out at the next anchorage if I can identify the problem.

sawingknots 08-11-2010 07:33 AM

most likely your engine/prop shaft is out of alignment compounded by too small dia. packing.don't run your engine until you correct this problem or you will ruin/score/groove your prop shaft

SEMIJim 08-11-2010 08:16 AM

Quote:

Originally Posted by stevemac00 (Post 631257)
I'm getting ready to motor out the Erie Canal so I changed the packing. I didn't know the size and used 3/16 but it didn't quite fill the gap between the nut and shaft so I cut one the size of the nut and another the size of the shaft so they'ed fill the gap.

Instead of going out and getting the correct size packing material? Why would you do that? Even the Gore stuff is only about $15 for enough to re-pack your stuffing box twice.

Quote:

Originally Posted by stevemac00 (Post 631257)
... now I have some bronze dust in the bilge drain as shown in photo.

Looking for suggestions as what is causing this...

Looks like a stainless shaft and bronze stuffing box. My guess: The packing material is bound-up on the shaft, is spinning/turning in the stuffing box, and eating your stuffing box.

Quote:

Originally Posted by stevemac00 (Post 631257)
... and what I should do to stop it.

Um... install propery-sized packing material?

Quote:

Originally Posted by stevemac00 (Post 631257)
I used syntek PTFE and lube.

"Lube?" PTFE packing material requires no "lube."

Quote:

Originally Posted by stevemac00 (Post 631257)
I have some more with me so I could change it out at the next anchorage ...

Insanity: Doing the same thing over and over, and expecting different results.

Suggest you obtain and install the proper size packing material before you damage your stuffing box, your prop shaft, or both. (If you haven't already.)

Jim

zz4gta 08-11-2010 08:37 AM

+1 to Semi Jim.

stevemac00 08-12-2010 09:28 AM

Thanks for the humility Jim. In case others read this, here's what we learned. We were told our boat uses 3/16. The last time marina serviced the packing they used 3/16. Another PSC owner used 3/16. So I bought 3/16. I also bought 1/4 just in case because I knew it was likely we would be unable to have access to supplies at times.

I was able to get to a dock lastnight and remove the old 3/16 packing. It looked in perfect shape and came off without any fraying I could find. (Not much water came in and I just wrapped a towel around the shaft so it would drip instead of spraying.)

Since the inspection of the packing looked good I hesitated putting in the 1/4. It was a tight fit but I was able to get it in using the side of a wrench. After each strip I tightened the nut up to push it in. I got three strips installed and hand tightened slightly. Today there is no water dripping but I'll recheck after break in. The shaft is not hot nor was it scored.

I'm still unclear what caused the bronze dust. Perhaps there was a small piece of thread caught on the shaft and turning in the nut.

sailingdog 08-12-2010 10:38 AM

I'd point out that if you're using a traditional stuffing box, regardless of the packing material, and it isn't DRIPPING...then you've overtightened more likely than not and are probably scoring the shaft. A traditional stuffing box NEEDS WATER as a lubricant, and if it isn't dripping at least a little bit, especially when the shaft is turning—it is probably running DRY. Even the GFO Goretex packing material REQUIRES SOME WATER PASSING THROUGH IT.

remetau 08-12-2010 10:43 AM

Ours does not drip when the shaft is not turning.

This is from Don Casey:

"Water is required to lubricate conventional packing, so a properly adjusted stuffing box can be watertight when the shaft is stopped, but it must drip when the shaft is turning."

SEMIJim 08-12-2010 10:51 AM

Quote:

Originally Posted by stevemac00 (Post 631666)
Thanks for the humility Jim.

Wasn't trying to humble you. Was trying to keep you from damaging your boat, possibly leaving yourself stranded somewhere, possibly putting yourself at the mercy of a boatyard with less-than-honourable intentions for emergency repairs, or expen$ive repairs even at a good yard.

Quote:

Originally Posted by stevemac00 (Post 631666)
Since the inspection of the packing looked good I hesitated putting in the 1/4. It was a tight fit but I was able to get it in using the side of a wrench.

Without knowing your definition of "tight," I don't know if it was right or wrong. In the end I have to go back to your OP, where you wrote "...3/16 ... didn't quite fill the gap between the nut and shaft ..." and that you basically "stacked" one ring outside the other.

The packing material shouldn't be "tight," per se, but it should fill the gap between the outside of the shaft and the inside of the stuffing box. Otherwise: How could it possibly seal?

Quote:

Originally Posted by stevemac00 (Post 631666)
After each strip I tightened the nut up to push it in.

That can work, but it's kind of painstaking, and you run the chance of not ending-up with the joints in each ring offset from one another.

Main Sail, I think it is, recommends fabricating a "pusher" out of rigid PVC. I just pushed mine in, gently and carefully, with a large-ish flat-bladed screw driver.

Quote:

Originally Posted by stevemac00 (Post 631666)
I got three strips installed and hand tightened slightly.

Sounds right to me!

Quote:

Originally Posted by stevemac00 (Post 631666)
I'm still unclear what caused the bronze dust.

Probably hard to do, but it sure would've been interesting to see the inside of your stuffing box. My guess is it's real shiny and has an ever-so-slightly larger i.d. ;)

Hope the new packing material has you fixed up, and I apologize for coming across poorly.

You might care to peruse Main Sail's Re-Packing A Traditional Stuffing Box. Very informative.

Jim

sailingdog 08-12-2010 10:59 AM

Yes, but on many boats, the stuffing box will drip very slowly when the shaft is not turning. If the stuffing box heats up noticeably when you're motoring, then it isn't being lubricated sufficiently—and you must adjust the stuffing box for when it is turning—and if it drips when the shaft isn't rotating, you just have to live with it.

Quote:

Originally Posted by remetau (Post 631691)
Ours does not drip when the shaft is not turning.

This is from Don Casey:

"Water is required to lubricate conventional packing, so a properly adjusted stuffing box can be watertight when the shaft is stopped, but it must drip when the shaft is turning."


DrB 08-12-2010 12:19 PM

Boundarys on Hot
 
Quote:

Originally Posted by sailingdog (Post 631699)
Yes, but on many boats, the stuffing box will drip very slowly when the shaft is not turning. If the stuffing box heats up noticeably when you're motoring, then it isn't being lubricated sufficiently—and you must adjust the stuffing box for when it is turning—and if it drips when the shaft isn't rotating, you just have to live with it.

SD and/or others,

Curious to as to what everyone believes is "heats up noticeably" when referring to a SB. Are we talking warm to the touch, hot to the touch, a few degrees above the water temp? My SB is pretty tight as in it doesn't let in water at all when at rest. I don't know what the drip rate is, maybe a drip or two every 1 to 2 minutes when running, but after the shaft has been turning for a several minutes, the SB area doesn't feel different than the shaft a few inches above it or the coupling. Not too concerned about my set-up, just curious on the "heats up noticeably" comment.

FWIW, I am running the West Marine GTU Gore Shaft Packing Material as my SB packing. 4 wraps.


All times are GMT -4. The time now is 10:42 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012