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Old 10-14-2017, 02:01 PM   #1
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packing gland question

I pulled apart my Marine Trader's packing glands today and got the old packing out. Each one had 5 wraps of packing. These packing glands are a little different from what I had on past sailboats, and I have 2 questions.
  1. There is a raw water line running from the top of the packing gland to the transmission's oil cooler. Does water run from the packing gland to the oil cooler, or the other way around?
  2. Are these packing glands designed to drip when the shaft is turning?


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Old 10-14-2017, 02:09 PM   #2
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I'd guess it was from your transmission to cool the shaft.

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Old 10-14-2017, 02:42 PM   #3
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Yes...and maybe. Yes, the cooling water (that's what it is for) flows TO the packing gland. Maybe it drips...but this depends largely on how well it has been packed, the state/age of the packing; and the type of packing used (amongst other things). As you have removed the old packing (are you SURE you got it all? The inner-most ring can end up looking like and being almost as hard as metal), you have an opportunity to use one of the newer packing materials like GFO. This can be nipped up tight enough to completely stop drips, without overheating the stuffing box. You should be able to keep your hand on the bronze 'box' without any difficulty at cruising rpm, irrespective of stuffing material used. Much hotter than that and your packing will be destroyed and the box will leak like crazy.
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Old 10-14-2017, 03:02 PM   #4
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They are designed to drip. They donít need to drip if they stay cool. If you put 5 winds of packing back in you should be able to adjust to a point of cool to the touch and no drip while the shafts turn.
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Old 10-14-2017, 03:27 PM   #5
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I would not recommend removing all the packing while the boat is in the water.
That drip drip drip will become a gush.
Just add another ring of packing.
If on the hard and you elect to remove all the packing, when inserting the new rings of packing, stagger the cuts around the shaft. When the boat goes back into the water, be at the packing gland, ready to tighten it up. You may need to add another ring of packing. Years ago, in the Navy, each pump and packing gland had tech manuals and diagrams to indicate the optimum size and number of packing rings. With recreational boats, I doubt if such documentation ever existed beyond the builder's yard.
The size of packing, there are a number of ways.... measure a ring of packing, allow for compression and buy the closest size or call the builder or pump manufacturer. You may also find the specs on-line too.
There are at least two ways to cut the packing, for a butt match or a step cut. I have never run into anyone who uses the stop cut. Just too much time to cut the steps and the results are the same.
I cheated, I switched to drip-less for the shaft and the rudder stock.
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Old 10-14-2017, 03:46 PM   #6
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Yes have the rings precut if able to.....

It is not as critical as some make it out to be. With 4 or more rings and a good squeeze. It becomes pretty much one mass.

If you take all the packing out and you are ready, again, no big deal. Sure some water rusges in...think about how much. Width of packing times circumfrence....hows that stack up to a hose area? For my 1.5 inch shaft, I figure its equivalent to a 3/4 hose gushing. With acrag, hardly much comes in no matter what, even if your first time and you are really slow.
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Old 10-14-2017, 04:35 PM   #7
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In modern packing, water addition to packing is usually more for flushing rather than cooling. If a flushing connection is present the packing would usually have a lantern ring. It is fairly useless without a lantern ring. You can buy lantern ring material made out of PTFE and cut like a piece of packing and install if you like. I wouldn't bother. Taking the packing out will not really turn into a gush while in the water. The annulus between the shaft and gland is fairly small area wise and the head pressure is low. Precut rings are nice, it you can cut them yourself with a mandrel (chunk of pipe the same diameter).
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Old 10-14-2017, 09:19 PM   #8
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As pointed out you can change a packing in the water. Every time I've redone the packing it's done in the water. Yes, you will get water coming in but the bilge pump will easily handle it.

Have a SHARP knife to cut the packing. The Olfas are great . Use of a mandrel, old piece of shafting, would be good otherwise I carefully cut the packing on the exposed section shaft. Make the cuts on an angle so when squeezed the gaps close. Stagger the cuts when installing so they DO NOT line up with the other packing pieces.

I use a piece of plastic pipe split lengthwise to use as a pressing/pushing tool to carefully push the packing into the holder/box. DO not use a screwdriver or similar or you may very well wreck the packing by punching through or tearing it. I've done it.

Three or four rings is all that is needed. Snug the press part of the stuff box up evenly but only lightly to stop a geyser. Then I run the engine in gear at idle and watch and slowly tighten the box up untill I get a drip rate I'm happy with. It will need to be checked again after a few hours are put on as more wear will occur. Once set properly that second adjustment should last many months with minor tweaks.

I also install a cut up old fender over the stuff box to catch the water spray so it does not fly all over the place. Have spray will travel, far and wide and cause rusting on the engine and gear and any other steel components within several feet sometimes.

A small fender, I.D. about the size of the stuff box. Cut long enough to cover the box. Cut off the ear so the hole is big enough for the shaft. Split the piece lengthwise so it can be wrapped over the stuff box with the split down so spray will be caught and then drip into the bilge. Secure the fender piece with a clamp lightly so it stays put. It is easily removed for inspection and adjustment. I keep the the nut runner nearby along with the dedicated wrenches so I do not have to dig through my tool box. That wore thin many years ago for some jobs.
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Old 10-14-2017, 11:10 PM   #9
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Clean and carefully inspect the shaft where it rides in the packing.
Can't tell for sure from the pic, but might have corrosion problem there.
This often occurs on boats that have spent too much time without exercise!
Another good reason to flush the raw water system with fresh water after each use.
Use plenty of teflon grease when installing packing, smear all sides of each ring liberally before installing. It's kind of messy, but pretty much insures that it won't leak.
I like to install a grease fitting just at the edge of the first (as installed) ring, and shoot it up with a good saltwater proof grease. Add a couple of pumps of grease on a regular basis, and especially if the boat won't be used for a while.
You can lead a horse to water,
But you can't make him ski...
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Old 10-15-2017, 06:19 AM   #10
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I dont think it is salt water corroding the shaft, its the oxygen in the water that keeps the stainless..... stainless.....

Oxygen depletes in stagnant water, such as under packing and leads to corrosion of stainless.

So that part of flushing may not be as important.

Many thanks to RTF who caught my previous posting error concerning oxygen and stainless in case anyone else caught it.

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