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Old 05-23-2014, 10:19 PM   #1
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Stuffing box cooling line

I had Victoriana hauled out for new bottom paint and to have the stuffing box packing replaced. When the yard was doing the replacement of the packing the water line fitting into the top of the stuffing box sheared off. Of course this happens on a Friday and there is no one useful around on the weekend

My current plan is to clean up the threads in the stuffing box and see if there is anything left on it; if there is screw in a new fitting. I'm just not sure what I will do if there isn't any thread left.

Does anyone have any other suggestions or fixes?

Just out of curiosity what has your experiences been with just replacing the stuffing box with a new one or switching over to a dripless setup.
(cost, effort, benefit)

Thanks
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Old 05-23-2014, 10:41 PM   #2
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Greetings,
Mr. V. Aw rats! I feel your pain. Make sure you have enough threads left to effect a proper connection. I would think a minimum of 4 might do. Failing that, would it be possible to drill out the hole, tap it and screw in a new fitting? Personally, I do not like the drip-less stuffing boxes but YMMV. If you were in a real jamb, I expect you could use something like JB weld for a temporary fix.
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Old 05-23-2014, 11:56 PM   #3
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You are fortunate it broke off while on the hill!!!

Try to extract the remnant. A good mechanic can usually extract a broken off NPT fitting, but sometimes they are too stuck. Once out, the fitting can be replaced. Absolutely use the right alloy for the fitting. That it broke in the first place implies the wrong alloy was used. Brass in bronze, no good. Bronze in bronze, ok.

Chances are if you have a slow moving boat, there is no need for a cooling line at all. You could cap it off or plug it, and just monitor temp until packing seats in.
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Old 05-24-2014, 01:23 AM   #4
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Ski brings up an interesting point. These cooling lines are typically small, maybe 1/4 to 3/8 inch, and they carry salt water. Does anybody make a hose barb that small in bronze?
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Old 05-24-2014, 01:31 AM   #5
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I couldn't find a bronze one when I replaced ours, so I used a nylon one ten years ago.
Check it yearly and it is doing fine.
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Old 05-24-2014, 02:08 AM   #6
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I don't have a cooling line. I just replaced the stuffing and greased it and adjusted it once or twice and good to go. I can't imagine that your boat, (8 knots?) actually needs a line. I would be tempted to cap it off and monitor. Now, having said that, putting a plug in the stuffing box is going to be as much trouble as replacing the hose fitting...

Taking the stuffing box out and replacing it means pulling the shaft back and removing the coupling. This, however, might be an opportunity to align the engine if you haven't done it for a few years. You'll have to do the alignment in the water.

Some people use graphite packing in their stuffing box, which, I would like to point out, is at the top of the galvanic scale and can cause big problems for electrolysis, especially if you have an aluminum boat. Don't ask me how I know.
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Old 05-24-2014, 02:37 AM   #7
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Is this what we're talking about (notice the tube but ignore the disconnected shaft)? This is about ten feet from where the propeller shaft exits the boat.

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Old 05-24-2014, 07:10 AM   #8
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Quote:
Originally Posted by HopCar View Post
Ski brings up an interesting point. These cooling lines are typically small, maybe 1/4 to 3/8 inch, and they carry salt water. Does anybody make a hose barb that small in bronze?
Buck Algonquin has them listed as replacement parts for their injected boxes...can't imagine they would "brass" out with their rep/experience.
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Old 05-26-2014, 10:49 AM   #9
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Xsbank,
When you said graphite are you referring to PTFE? I had a friend recommend changing to that so I did. Then I had another friend say the old school flax is just fine.
Thanks,
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Old 05-26-2014, 11:22 AM   #10
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Quote:
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Ski brings up an interesting point. These cooling lines are typically small, maybe 1/4 to 3/8 inch, and they carry salt water. Does anybody make a hose barb that small in bronze?
You're right that they're small, and that makes them easy to plug. The mechanic who installed my engine suggested pulling the line off at the engine once per year and blowing on it to make sure it's not plugged.

Seems like a good idea, and I've been doing just that. Does anyone else check their lines?
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Old 05-26-2014, 11:50 AM   #11
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Yes...my boss want's us to do it on the assistance towing vessel after every job where we unground someone. We have had the lines plug from sand and even just pits of weed. The boats have PSS dripless packings and I'm nervous about breaking the nylon threaded barb off...but it is tough and taking the line off several times a week helps.

On my trawler it's even easier to reach and check....once you empty out the bottom of the aft head vanity.
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Old 05-26-2014, 12:12 PM   #12
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I run a standard bronze gland with goretex packing. No cooling line whatsoever, and I often cruise at 23kts. Gland stays cool. (it did take a long time to seat in, and did get hot then, but once broken in/seated in/whatever, it now runs cool).

I don't think the cooling line is needed at all on bronze glands in trawlers.

If you run PSS or Tides dripless, you do absolutely need cooling, and should check for flow or check for warm running seal.

Boats have sunk when dripless got hot and the plastic bushing melted and seized on shaft. Whole seal spins and rips the hose. Bad scene there.
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Old 05-26-2014, 02:44 PM   #13
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I don't think the cooling line is needed at all on bronze glands in trawlers.

Its not , but flax and everything buy Goretex does need water to carry off the heat in operation.

This means there will be a drip drip drip when the boat is stationary.

It is why the ceramic seals were created.

Far less fear of sinking when the ceramic bladder fails to simply go back in time to the cure dripping the flax era.

A , 6 oz or so bronze grease cup is hooked to the bearing,with copper tubing.

When the boat is secured a turn or two stops the drip.

In out 90/90 with Great Cabin aft the drip is easy to hear , and a reminder to reach under the sink for a turn or two.

Now with modern packing it is no longer required.

Out stuffing box is interesting , 18 rings of packing IS the stern bearing.

As a cruiser its easy to change the packing (which IS thee bearing) afloat .

Just count the rings as they come out and DO NOT pull #18.
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Old 05-26-2014, 04:28 PM   #14
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I've been running GFO packing dripless in trawlers and other non-aluminum vessels for decades and I've never had an over heating issue if the box is adjusted correctly. I do not recommend Teflon packing as I have seen it damage shafts on several occasions. YMMV

I have seen a stuffing box over heat on a trawler when the water line to it was not flowing water while the shaft was turning. But the packing was vey old and in need of replacement. Again, YMMV
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Old 05-26-2014, 04:33 PM   #15
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Any insight to why Teflon is bad and why the packing which if adjusted would have some water flow through it and it would be a water flow issue and not the packing itself?
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Old 05-27-2014, 06:44 AM   #16
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Any insight to why Teflon is bad and why the packing which if adjusted would have some water flow through it and it would be a water flow issue and not the packing itself?

The Teflon is very hard like the ancient flax.

It will hold a metal sliver or piece of sand , and cut a groove in the shaft .

The new packing is softer and the cutting item simply beds in the material that is not strong enough to hold it like a lathe tool.

Perhaps too the cooler running modern packing does not need water flow for cooling , so less trash is deliver to the bearing surface .
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Old 05-27-2014, 09:19 AM   #17
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Any insight to why Teflon is bad and why the packing which if adjusted would have some water flow through it and it would be a water flow issue and not the packing itself?
Basically what FF said. Teflon packing just seems to get very hard as it gets old and people seem to over tighten it as well for some reason.

GFO is so low friction that unless the box is way over tightened it runs cool with no water drips.

You can feel how low friction GFO is when you cut it. The blade just slides right through it with not much effort compared to old school packing.
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Old 05-27-2014, 10:31 AM   #18
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Spoiler alert.

Teflon is made out of PTFE.

GFO is made out of ePTFE.

They are made out of the same materials. PTFE yarn is made by sintering and skiving, or spinning and pulling a block of solid PTFE.

ePTFE is made by heating and rapidly streching PTFE which makes it porous.

The reason ePTFE or GFO is superior is that it is fluffy and full of air.

Gore had for many years had the patent for the methodology for creating expanded ( that's what the e stands for) PTFE. That patent has since expired. There are other manufacturers of ePTFE now.

I specify GFO only because it is easier to source with supply chain management types rather than suffer from the an unsuitable substitute. Other ePTFE packing can be used with great results as well.

To answer psneeld's question on dripping stuffing boxes...

It is possible to have water dripping out of a stuffing box without suitable lubrication if the packing is cut too short or just to the shaft size. Ideally packing should be cut so that it conforms to the ID of the stuffing box rather than the OD of the shaft. This forces the water path along the dynamic sealing surfaces as opposed to bypassing along the to the static sealing surface.
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Old 05-27-2014, 11:58 AM   #19
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Ideally packing should be cut so that it conforms to the ID of the stuffing box rather than the OD of the shaft. This forces the water path along the dynamic sealing surfaces as opposed to bypassing along the to the static sealing surface.
If the space between the shaft and the box is say 1/4" and you are using 1/4" packing, how do you cut the 1/4" packing so it doesn't fully fill the 1/4" space?

And even if you can keep a small space open between the shaft and packing for water flow, how would you keep the packing from crushing down onto the shaft as you tighten it to form a seal?
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Old 05-27-2014, 12:48 PM   #20
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If the space between the shaft and the box is say 1/4" and you are using 1/4" packing, how do you cut the 1/4" packing so it doesn't fully fill the 1/4" space?

And even if you can keep a small space open between the shaft and packing for water flow, how would you keep the packing from crushing down onto the shaft as you tighten it to form a seal?

This is for people who cut to length as they are cutting a square profile and then bending it into a circle.

Mandrel cutting is the best method because of this. If you cut you packing on the shaft (as I do) and then lay it flat you'll see that the ends are not square.

Tightening the gland nut exerts axial force on to the packing which is transmitted into radial compression. The ring closest to the gland nut receives most of the force. The ring at the bottom of the box receives the least. The first ring is over compressed, and the last ring is under compressed.

75% of the sealing is done by the first ring or two nearest the gland. Often times when packing is fit wrong a gap is present at the packing ring in the bottom of the stuffing box. Excessive leaking takes place, the gland gets over compressed and the first ring of packing is now dragging on the shaft, creating heat, robbing horsepower, and depending on the packing material, wearing away the shaft or packing.

Furthermore, braided packing, particularly lattice braid, will shrink in length when compressed.
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