Hot stuffing box, leaky stuffing box. Is there an in-between?

[Ryban]

I re-packed my stuffing box while out of the water recently. I used 3 rings of 1/4" packing, which is the same size and quantity as what came out. Perhaps one of the rings was cut just slightly over-sized, but the other two were cut so they were just touching when wrapped around the shaft.

If I tighten the stuffing box just to the point where the drips stop (without the shaft turning), and tighten down the lock nut in this position, the stuffing box gets very hot after several minutes in forward (190F on the IR gun). But if I loosen things by even just a little bit, I start getting drips without anything turning.

From what I've read online, this is absolutely unacceptable. So that makes me wonder if that one slightly oversized ring is causing problems, or if the new packing just needs some time to wear in?

If I am faced with re-packing, it won't be that much fun now that we're in the water, but it also won't be the end of the world. If I do have to re-pack, should I err on the side of rings being slightly too small?

[JimsCAL]

I would give it some time. The packing may not be properly seated. How much does it drip when backed off a bit and the shaft is stopped?

[Ryban]

Originally Posted by JimsCAL

I would give it some time. The packing may not be properly seated. How much does it drip when backed off a bit and the shaft is stopped?

A good amount, but perhaps with some fine tuning I can get it down to less than 10 a minute. Still too much, but might help get things cooled down until the packing can properly seat?

[JimsCAL]

That is a good amount.

I would try tightening it fairly hard with the shaft stopped and then back off. See if that helps seat the packing.

[Stu Jackson]

In all the stuffing box information I have read, from those I trust (like Maine Sail) the idea is to slowly tighten the box until you get to the desired point. None of the references I trust suggest backing off, ever, if you can avoid it.


You should have seated the packing properly inside the box when you installed it. Tightening the box may not work, and may make things worse.

[Ryban]

I'll keep a close eye on it for now, and re-assess the situation in a few days.

When I seated the rings, I did them one at time, tightening down the box each time to "seat" them snugly, then opened up the whole thing, added the next ring, and repeated. I don't know if this is standard procedure, but it seemed like a reasonable thing to do.

[Stu Jackson]

Ryban, good luck.


Don't know if you've ever seen this:


https://marinehowto.com/re-packing-a...-stuffing-box/

[wedivebc]

I would never tighten a stuffing box so much so that no water came out but would allow it to drip while running then slowly snug up on it until you had a slight drip while running. You can use a handheld temp gauge to find the sweet spot just before the temperature rises.

[Ryban]

Originally Posted by Stu Jackson

Don't know if you've ever seen this:

https://marinehowto.com/re-packing-a...-stuffing-box/

That's a good article, and I've skimmed through it in prep. for packing the box. Re-reading it in more detail this time, though, makes me wonder if I did indeed use the right packing material size.

I used 1/4", it seemed to be the same size as of what was in there, and though it was a bit of a tight fit, I suspected it was supposed to be. The next size down is 3/16", which I can attempt to use.

I also just came back from attempting to get the drip rate right, which has me at a bit of a dumb question. The dripping should be coming from where the shaft exits the box, right? Right now, the only dripping I'm getting is through the bronze threads on the box. Adjusting for drips in this location either leaves me with lots of drips, or no drips at all.

This leads me to believe that no water is getting through the packing material at all, and the box is certainly not tightened down too much. In fact, it's probably far too loose.

[Ryban]

Fearing I might have to re-stuff the box in the water, I decided to take off the packing nut completely just to see how much of a deluge I'd be experiencing, but only a trickle comes out -- about the same rate as when you think you turned off a faucet, but it's still running. Is this normal?

Here's a video:
https://photos.app.goo.gl/YVYBX8TSzQ4F9Eqe6

[CarlF]

Did you get all of the old rings out? And push the new packing in well with some sort of pusher? If not, it might have been so loose that when the shaft first turned the packing became twisted or misaligned. I think I'd pull it out and repack. 190 is way too hot.

In your video, the corrosion makes it looks like the nut was screwed in much farther before. If you compare the thickness of the packing you took out to what you put in would it account for this much of a difference? If not, it's another clue that you might not have seated the new stuffing and it's misaligned.

I don't think a slightly oversize ring is your problem. Don't leave a gap. Cut as closely as you can.

It takes new packing an hour or two to settle in. During this time, have it drip a lot to keep it cool. After an hour tighten it most of the way but still let it drip more than 4 drips a minute. It's more important to keep the shaft cool than get the drips to a minimum. It's also not unusual for stuffing to drip for a while after the engine has been stopped until things cool down. Even if it drips all night it will only be a few gallons of water.

Are you using flax or one of the teflon packings?

[Ryban]

I took the shaft out entirely, because I also wanted to replace the hose connecting the stuffing box to the stern tube. Thus, I had full and easy access to the inside of the stuffing box, and cleaned it out very well. Nothing was left inside.

I'm using PTFE Flax with Teflon, but now that I look closely at the fine print on the package, it does say I should be using a "Syntef"shaft packing lubricant when installing new packing -- which I did not do.

Again regarding the drips: I get no drips from where the shaft enters the packing nut. The only drips I get are between the threads of the male and female portions of the packing box -- which I can make go away with a few easy turns.

In any case, I'll be making a trip to the marine store this morning and will pick up some more packing, and I guess lubricant, and give this another go. I'll record the whole thing, too, so you lot can point out all my mistakes .

[Sailmonkey]

Originally Posted by Ryban

That's a good article, and I've skimmed through it in prep. for packing the box. Re-reading it in more detail this time, though, makes me wonder if I did indeed use the right packing material size.



I used 1/4", it seemed to be the same size as of what was in there, and though it was a bit of a tight fit, I suspected it was supposed to be. The next size down is 3/16", which I can attempt to use.



I also just came back from attempting to get the drip rate right, which has me at a bit of a dumb question. The dripping should be coming from where the shaft exits the box, right? Right now, the only dripping I'm getting is through the bronze threads on the box. Adjusting for drips in this location either leaves me with lots of drips, or no drips at all.



This leads me to believe that no water is getting through the packing material at all, and the box is certainly not tightened down too much. In fact, it's probably far too loose.

You’re correct, the dripping should be going through the nut, not the threads.

It seems to me that your packing may be too large. What is your shaft size?

[Ryban]

Just making sure, thanks!

The shaft is 25mm.

[RaymondR]

Maybe it's the packing type which is causing the problem. My recollection is that the usual packing used in boat prop shaft packing glands was graphite impregnated cotton.