# Stuffing Boxes for Dummies



## MacBlaze (Jan 18, 2016)

In the course of trying to trace a freshwater leak I noticed my stuffing box is now dripping fairly consistently at dock.

While I know the theory and have seen the diagrams, I actually know very little about stuffing boxes other than they help keep the wet stuff on the other side of the hull. Are the any issues associated with me taking a couple of wrenches to it to try and tighten it? Can I, in any way, make the problem worse? Should I wait until the next time I am near a yard and an emergency mechanic I can go to for a rescue after I f#ck it up completely?

Or am I just worrying about nothing?


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## capta (Jun 27, 2011)

Very simply, a standard 'stuffing box' or 'packing gland' has a few replaceable rings of 'packing' which circle the shaft in a tube. The tightening mechanism is only a fitted ring that compresses this packing which then expands around the shaft creating a nearly water tight seal. I say nearly, as a bit of water is necessary to cool where the packing compresses on the shaft as the shaft turns.
If flax packing is tightened too much, it can actually cut through a s/s shaft, so it is imperative that a bit of water drips out of the gland, but certainly not enough to spray the surrounding area.


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## Scotty C-M (Aug 14, 2013)

Good question, McBreezy - and good answer by Capta. I'm going to give you a website to check out: How to, by Compass Marine (Mainsail). It is a wealth of information. Go about halfway down and you will find information on the stuffing box. I took you to the "menu" page because I thought you might find it interesting to explore other topics as well. Have fun!

Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com


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## eherlihy (Jan 2, 2007)

This is a stuffing box and shaft log hose;









This is what it looks like from the inside;









Here, courtesy of alberg30.org, is a picture with the parts labeled;









Loosen the lock nut, by placing a wrench on the stuffing box and the lock nut, and tightening the nut toward the stuffing box. Then tighten the box nut, by placing a wrench on the stuffing box and the box nut, and tightening the box nut toward the stuffing box ¼ turn. Finally, tighten the lock nut by placing a wrench on the lock nut, and the box nut, and tighten the lock nut away from the stuffing box. Check the rate of leakage. If the same, tighten the stuffing box another ¼ turn. If worse, get help and install new packing material.


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## MacBlaze (Jan 18, 2016)

Thanks all. The key question however, remains unanswered. Is sitting at a dock far from competent help the place to experiment with this? Can I really screw this up?


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## MacBlaze (Jan 18, 2016)

> *WARNING: If you have not attempted this type of DIY job before it's best to do it with the boat out of the water for obvious reasons. With the female flax nut removed water will flow in to the boat from between the male end of the box and the shaft!


Ah. Found it.


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## Omatako (Sep 14, 2003)

capta said:


> If flax packing is tightened too much, it can actually cut through a s/s shaft, so it is imperative that a bit of water drips out of the gland, but certainly not enough to spray the surrounding area.


OK, just to be clear (and prevent widespread panic)  the packing in a stuffing box will not cut "through" the shaft. It will however cut into the shaft if there is inadequate lubrication from the water that should be allowed to minutely leak past.

When the shaft gets damaged, the leak gets worse so you have to tighten again, if you over-tighten again then the shaft gets worn again and the leak is back and so on . . . .

In fact once the shaft has a track worn into it, the only way the stop the leak is to change the length of the hose to position the packing on a virgin surface on the shaft. This is not always possible in which case regrettably it's probably going to need a new shaft.

Correct adjustment should see no water when the shaft is stationary and a drop every 5 to 10 seconds when the shaft is turning.


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## albrazzi (Oct 15, 2014)

MacBlaze said:


> Thanks all. The key question however, remains unanswered. Is sitting at a dock far from competent help the place to experiment with this? Can I really screw this up?


The most important part of the system is the short hose, it is a heavy 4 or 6 ply hose much heavier than any regular hose, if its the right one and in good condition and double clamped with good all SS clamps then there's not much you can do wrong tightening the packing nut. Start by making sure the nut and lock are free and lubricated green bronze is fine, some marine never seize is good to keep the nuts free. I would start with a fine brass wire brush and clean the threads put some never seize behind the lock nut and turn it back a few turns that will tell you if its jammed up badly before turning the top nut (Packing Gland) hold the hex on the body. most I have seen have hexes like a regular nut instead of the one in the photo use the right tool for the style you have. Tighten 1/8 turn at a time its easy to over do it and if too tight will overheat. Properly adjusted it will drip just a little underway but not at rest. All this depends on the packing still being good, last one I changed came out as dust chips didn't even look like packing. Replacing the rings you need to do on the hard.


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## Capt Len (Oct 9, 2011)

Couple of not so obvious bits. If over tightened,the over heat will cause the tallow to ooze out of packing ,,not good so packing may not leak now but needs to be replaced before it buggs the shaft. Rarely you find a left hand threaded stuffing box. (duel engine installations?) Check this before getting a really big wrench.


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## Chas H (Sep 6, 2013)

Then when you are through frogging around with the stuffing box and it is working well you'll have time to explore a PSS shaft seal.

-- PYI Inc. Max-Prop PSS Shaft Seal Seaview Radar Mounts R&D --

-CH


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## travlin-easy (Dec 24, 2010)

I just wish I were skinny enough to reach my stuffing box. 

Gary


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## chris95040 (Sep 26, 2008)

MacBlaze said:


> Thanks all. The key question however, remains unanswered. Is sitting at a dock far from competent help the place to experiment with this? Can I really screw this up?


People are giving excellent advice here, but to be clear: the stuffing box is a very resilient, failsafe seal. Its not going to sink your boat if you overtighten it.

If yours is of the flexible variety, take the time to inspect hose clamps all around, the hose too, because if THAT stuff fails its a major leak. Thats true regardless of if you're down there tinkering...

Adjusting the nut too tightly might cause a funny burny smell, and if left that way would certainly score your shaft a bit, so if you overtighten it, don't leave it that way.


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## Bob142 (May 27, 2012)

As long as the hose and threads are all in good shape not a lot to worry about...unless you want to change all of the packing you don't need to be out of the water...as long as you are reasonably quick you can add a ring or two of packing without taking on a lot of water...often this will get you through another season...


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## JimsCAL (May 23, 2007)

You can most certainly adjust your stuffing box while in the water. Can't really do it unless you are. As has been noted, tighten it a bit at a time until you get an occasional drip when the shaft is turning. If you overtighten, back off until it starts dripping again, then begin the gradual tightening process all over.


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## Wes (Mar 27, 2016)

And by the way, a drip every 30 seconds or so is NOT a bad thing...lots of times the "optimal" adjustment point is such that when standing still there is virtually no drip, when in gear, a drip every 30 seconds can appear. Like others have said, too tight will cause issues, too loose is a matter of taking another 1/4 turn. If that doesn't solve the problem, then it may be time to repack the stuffing box. You can do this in the water. I would get someone who has done it before to help you so there won't be any panic. Some water DOES come in the boat, but maybe only a gallon or three... It's sorta like pulling out the paddle wheel on your speedo to clean it...yes, some water does come in...


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## deniseO30 (Nov 27, 2006)

If it's not been said.. *never use one wrench on the S*B some people have been lucky but it's just WAY too easy to twist the hose that couples the SB to the shaft log. and if the the old rubber is...* OLD..* it's possibly* BRITTLE..* and you should be *Cautious* if you have any doubt in your ability to screw up things..And I thought I was the only one with that ability LOL


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