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Old 04-21-2019, 05:49 PM   #1
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hot seals

recently my mechanic repacked my stuffing box with graphite. I had teflon before He told me the graphite packing should not drip at all even underway. I've read that graphite disperses heat much better than teflon and drips less but I still had concerns. We left the marina -idiling for ten minutes then slowly got to 1600rpm( 12mph). 5-10 minutes the temps on both seals was over 200F . After drifting for 30 minutes - temps down to 130F. Any increase above idle drove it higher.There was some black fluid bubbling out -? liquifying graphite. I'm assuming he overtightened the stuffing boxes.I want to go back to dripping seals. Appreciate thoughts. OB
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Old 04-21-2019, 06:03 PM   #2
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Does your shaft tube have a water supply coming from the engine?

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Old 04-21-2019, 06:22 PM   #3
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Even with Teflon, my stuufung boxes properly tightened only get warm and don't really drip. More of an ooze that will barely wet the tip of my finger.
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Old 04-21-2019, 06:31 PM   #4
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Back them off till they drip. Run them. Then take a small turn on them until the drip almost stops. Then check them for temp.
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Old 04-21-2019, 07:00 PM   #5
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If they got hot enough to bubble the packing, there's a chance they'll have to be re-packed. The heat glazes the packing and sometimes it just won't recover. It's not a terribly difficult job, and it can be done in the water. Then again, if you paid someone to do it, I suppose you'd expect they'd do it right the 1st time rather than do it over. for free.....
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Old 04-21-2019, 07:31 PM   #6
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True graphite packing won't melt. It's what is used in superheated steam valves.

What you probably have is a graphite impregnated material if some type.

GFO is a common shaft packing used in marine applications. It is graphite in a Goretex fiber. It is dull grey and will turn your fingers shiny. True GFO has GFO stamped on in in white letters every inch or so..

It sounds like the gland was loaded too much on start up. Common mistake. It needs to be run in, over a period of hours, until it is consolidated properly.

Repack it. And start with hand tight gland (or finger tight gland nuts). Run it and tighten it up slowly every hour. In 2-4 hours it will be good for many many years.
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Old 04-21-2019, 08:47 PM   #7
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Thanks for the help. The graphite was put in without cutting strips. Does it need to be cut in sections like teflon?
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Old 04-21-2019, 09:02 PM   #8
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Quote:
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Thanks for the help. The graphite was put in without cutting strips. Does it need to be cut in sections like teflon?
I've used the GFO, IIRC the instructions recommend cutting strips to fit the circumference of the shaft, cutting on a 45 degree so the ends overlap, not butt. The joints should be offset for each successive ring so the lap is covered by a solid section.

There's a handy removal tool, like a mini-corkscrew and a flex spring on a t-handle. Sized for the packing dimension. Makes removing the old packing a snap.
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Old 04-21-2019, 09:33 PM   #9
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Yes, as Maerin wrote.

Frankly, any "mechanic" that spiral wound packing on a shaft, must not have any formal training in marine or industrial mechanics.
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Old 04-21-2019, 11:40 PM   #10
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C'mon guys take a step forward and save yourself all that hassle, fit a PSS seal fit it and apart from periodic checks forget it. k.i.s.s
I've had one for over15 years with thousands of miles cruising with no trouble at all.
If your handy with the spanners you can even fit it yourself while the boats in the water if your not nervous.
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Old 04-22-2019, 05:43 AM   #11
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At this point in time I think the GFO will do away with complex seals .

KISS always works , tho even with GFO a tiny bit of knowledge is required to install the packing properly.

The yard guy needs to go back to,,,

"will that be paper or plastic bags madam"
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Old 04-22-2019, 07:05 AM   #12
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At this point in time I think the GFO will do away with complex seals .

KISS always works , tho even with GFO a tiny bit of knowledge is required to install the packing properly.

The yard guy needs to go back to,,,

"will that be paper or plastic bags madam"

And THAT'S how they earn the unflattering title of "yard monkey".
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Old 04-22-2019, 07:35 AM   #13
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I've always repacked my own stuffing boxes and I've repacked the packing on hundreds of valves in heavy industry. never once have I seen the packing put in in one piece
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Old 04-22-2019, 08:39 AM   #14
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Sometimes if the packing is running hot, loosening it does not really relieve the pressure. You have to loosen the gland then whack on the side of the gland to get a little water gap to open up. Once it is dribbling, get someone to drive the boat and snug just a tiny bit at a time til drip rate goes down and temps stay cool.

Some glands once re-packed take a lot of running time to "break in" or whatever, and like to run hot. This happened on my ride. Then one magic day it decided it wanted to run cool. It has stayed running cool for the last few thousand miles!! And only a drip now and then.
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Old 04-22-2019, 09:55 AM   #15
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Quote:
Originally Posted by Irish Rambler View Post
C'mon guys take a step forward and save yourself all that hassle, fit a PSS seal fit it and apart from periodic checks forget it. k.i.s.s
I've had one for over15 years with thousands of miles cruising with no trouble at all.
If your handy with the spanners you can even fit it yourself while the boats in the water if your not nervous.
I've been formally trained and working with mechanical seals and packing on rotating shafts and valve stems for 34 years.

They both have their pros and cons.

But, for the simple, low shaft speed, clean liquid, non-toxic fluid application of a boat shaft, I'll stick with my packing, thanks.
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Old 04-29-2019, 02:47 PM   #16
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I agree. Keep it simple S.......
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Old 04-29-2019, 04:10 PM   #17
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I would not use graphite packing with a stainless steel shaft due to galvanic corrosion issues.

Teflon is the way to go. In the millwright trade packing material was always cut as individual rings on a 45 degree angle and the cuts staggered to prevent blowby. This is generally more of an issue with high pressures like you find on steam turbines, high pressure pumps and the like but it's still good practice.

Another reason to use individual rings is so that if a leak develops you can pull one or two rings and put in new ones to control the leak till later. You can't do that with a single spiral bound piece.
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Old 04-29-2019, 06:43 PM   #18
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Graphite impregnated packing will not cause your shafts to corrode any more than other types of packing or dripless seals.
The key to keeping corrosion at bay in the packing is the regular use of a fresh water flush.
I’ve seen fierce corrosion occur in all types of packing when it’s left steeping in salt water for extended periods.
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Old 04-29-2019, 07:22 PM   #19
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I disagree completely.

Here's just one link to data regarding graphite and stainless. Why even take the risk when there are other materials available. Packing is cheap compared to a getting a drive shaft coated and machined.

https://www.materials.sandvik/en/materials-center/corrosion/wet-corrosion/galvanic-corrosion/
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Old 04-29-2019, 09:51 PM   #20
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packing woes

hi all,
ok I bought my boat in march. drove it from just above ft. myers to Carrabelle. once docked I noticed the bilge running every 10 minutes or so. since this is my first inboard boat I am unfamiliar with packing stuffing boxes etc. the marina recommended martin marine, a local boat mechanic. he came by, checked the boat , said it needed stuffing after trying to tighten the nut. he did not have any with him. in retrospect, since this is a common , simple repair I guess I should have been suspicious. in any event, he packed it the following day, I headed out the next day to panama city. as soon as I anchored the bilge fired off. I checked and had a steady stream of water running. I tightened it a bit and had a regular drip. I had read and watched some posts so I felt comfortable I had it under control. headed out in the morning , that evening , same thing. tightened again but still flowing. day after day til I got to mobile bay where the mechanics checked it, said I had the wrong size packing, thanks, Martin Marine ( I would never use him again ) . anyway it stopped leaking, they used Teflon, told me to run it an hour so next day I headed north up through mobile. checked it in an hour, running water, tightened, it stopped so I continued my trip. that evening, anchored out, same darn thing. tightened some more, stopped leak. finally at bobby's fish camp I could not get it any tighter but a local guy put a pipe wrench to it and it stopped. now the boat is in demopolis. they are going to check it it out. boat will be there on the hard after tomorrow and they will investigate. wondering what they are going to find. bad shaft, bad cutlass bearing, I don't know. any ideas folks ?
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