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

[Tillerjockey]

I've had different boats with stuffing boxes. On past boats if the dripping was more than 10 drips per min not running, I'd tighten it until the drip rate was 3-4. All ran warm to the touch. One I replaced with the old style packing with no problems. My current stuffing box doesn't drip and runs warm to the touch. I'm surmising that each installation is different, maybe mostly due to shaft alignment. If you can't fix the problem, give it to a mechanic at the marina. They've seen a lot of these.

[Bear15]

Last year had the yard repack it, they used teflon, 3 rings. I could not get the box to stop over heating, I got some traditional flax packing and changed in the water, the teflon ones were cut to short and there was only 3, we were able to get 4 in no problem, they are idiots and I will never get them to do a job again unless I absolutely can't do myself, anyway ran perfect last year, ran perfect this year until about the last month of the season, it started dripping too much while not running, had it not dripping at all while not running and running cool and dripping while turning, just couldn't find the sweet spot again so was forced to leave it dripping to the point where it wouldn't get hot while running, I have a little tray made up that fits underneath and catches the water, usually it was able to catch everything from the day and I would suck out with a shop vac at the end of the day, the last month or so it was even over flowing the tray a little everyday, I'll be tinkering again when it goes back in, in the spring.

[eyschulman]

There are variables that have to be accounted for. Is the packing the right size? What kind of packing was used. How was it installed? Is there a break-in procedure needed after installation? For those who think you can't have dripless packing think again. There are at least two types of dripless packing on the market the soft stuff and the harder graphite type. Both work fine when properly installed.

[Squanderbucks]

I'll bet the 1/4 inch stuf is the right size - it is the most universal. Dis you stagger the cut ends so none of the are aligned? Some people advocate placing a zirc fitting in the gland nut and greasing it occasionally.
If you do have to re-do it in the water - here is a trick that worked for me - it involves going overboard and pushing two soft plastic fishing baits ( the 6 inch or so Slugo or similar type) onto the hole around the shaft with a blunt object oriented head to tail.
When I did mine on a trip to the Abacos a couple of years ago I was able to work just like on dry land with no drip at all. Then when I cranked it up and put it in gear they just blew out and that was that. Used a fish hook to get the old packing out.

[Ryban]

PTFE is the only type of packing I can find in the chandleries here. I can't find their "Syntef" name-brand lube, but I believe it's just PTFE lubricant, which I have onboard.

Today I picked up a pack of 3/16" and 1/4". It took a long time, but eventually I got all 3 rings of the old packing out.

I measured the inside diameter of the packing nut to be ~37mm, and the shaft is 25mm. That means my gap is 12/2 = 6mm... roughly. 1/4" = 6.35mm, 3/16" = 4.76mm.

Thus, 3/16" is probably too small to properly pack the nut, but I cut a new ring of 3/16", inserted it, and tightened down the nut to seat it, just to see how it would fit. I only tested one ring, but the result was a large quantity of water coming out from the shaft opening.

I then removed this 3/16" ring, and cut a new one from 1/4" and repeated the same procedure, except for that I also lubricated it with the PTFE lube I have. This time, absolutely no water comes from the shaft opening, even when the packing nut is backed off considerably (water comes from the threads at this point).

I also ran the engine in gear with the single 1/4" lubed ring, and the packing nut got very hot again.

I'm a bit stuck on how to proceed. I'm very tempted to try to pack in tightly 3 of the 3/16" rings, and hope this results in an only slightly dripping shaft seal, which I think is preferable to a dripless one that overheats... I did buy extra 3/16", so it won't hurt too much to try.

[Ryban]

Originally Posted by Squanderbucks

I'll bet the 1/4 inch stuf is the right size - it is the most universal. Dis you stagger the cut ends so none of the are aligned? Some people advocate placing a zirc fitting in the gland nut and greasing it occasionally.
If you do have to re-do it in the water - here is a trick that worked for me - it involves going overboard and pushing two soft plastic fishing baits ( the 6 inch or so Slugo or similar type) onto the hole around the shaft with a blunt object oriented head to tail.

The 3 cuts were offset, but again, no water was coming from where the shaft enters the packing nut, regardless of how tight or loose the packing nut was, so I don't think this was an issue.

The amount of water entering the boat is very low with the packing nut off. Maybe 1L/min. So this isn't an issue in terms of servicing in the water.

[Dooglas]

Originally Posted by 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.

I'm not so sure about your recollection. Graphite impregnated cotton packing is certainly used in some pumps, valves, and the like; but PTFE flax packing is the standard for propeller shaft stuffing boxes in the marine industry.

[River Cruiser]

I had a marina repack my shaftlogs a few years back. I had problems from the get go on the SB shaft. It ran to hot I loosened it and it leaked way to much but ran cool. I ran it like this for awhile and then decided to repack it myself. The marina used 1/4” and using drill bits to check the size I came up with 3/16”. I repacked with 3/16” and haven’t had anymore problems, runs cool and leaks while running and doesn’t while setting.

[Ryban]

Originally Posted by River Cruiser

I had a marina repack my shaftlogs a few years back. I had problems from the get go on the SB shaft. It ran to hot I loosened it and it leaked way to much but ran cool. I ran it like this for awhile and then decided to repack it myself. The marina used 1/4” and using drill bits to check the size I came up with 3/16”. I repacked with 3/16” and haven’t had anymore problems, runs cool and leaks while running and doesn’t while setting.

That's a clever way to measure the gap. So clever, in fact, that I just went over and tried this, but it only confirms that it's a lot closer to 1/4" than it is 3/16".

I can only assume that I just need to be patient at this point and let the new packing wear in a bit.

The only other thing I can think of is an alignment issue. But I just had the whole shaft out, and the packing box is on a flexible rubber hose (see photo).

[CHRISBENJES]

Try 4 rings if they fit. I had different mechanics pack my 2 shafts. One used 3 rings because he said that was enough. The other used 4 rings. Guess which one I had to have redone? 3 rings was not enough!

[Moxie 38]

Hi Ryban, I have read your thread here from beginning to end and, though it may be a minor point, no one else seems to have mentioned that when cutting the three rings of packing, it's a good idea to cut each ring at an angle when over-wrapping on the shaft to get the proper length so that they close more reliably at the seams. Also, I seem to recall when I did mine earlier this year that it was strongly advised to set each layer with the cut approximately 120 degrees from the last one so as to not have all yhe seams close to each other. Lastly, a few articles that I read before attempting this all stated that it should not be over-tightened but deliberately set snug by hand for a period of a day or so and allowed to drip then tightened to 2-3 drops per minute with the shaft turning. Hope this is useful.

[Ryban]

Thanks, and yup, both times the rings were cut at 45-degree angles and offset on the shaft at 120-degree angles on the shaft.

I still don't like this situation. Tomorrow we need to get off the dock and go back on anchor. It's going to be a lot more difficult to test at that point, as I can't easily put the boat in gear for any period of time with the hook down and a bunch of neighbors around.

One person has said "Maybe you should flatten the 1/4-inch flax down to 6mm" and another person has said "maybe you should use the 3/16-inch ones, use a few extra rings, and make them really flat by tightening down the nut."

Neither solution sounds really great, but nor does an overheating stuffing box.

[skipperpete]

It might be time to check the alignment of the shaft/ coupling/ gearbox flange. It's a good idea to check whether the propeller shaft is centered in the sterntube at the time of reassembly. An ancient rubber hose connecting the stern gland to the shaft tube has had a long time to " relax" into a comfy spot with a badly aligned shaft but a new connector hose will try to centralize the shaft and the seal will behave as you describe.
"Badly aligned "does not always mean an observable problem at the coupling, it can often simply be a shaft running off center in the shaft tube.

[Mike Banks]

Stuffing boxes are SUPPOSED to have a slight drip--because water is the lubrication for those plastic bearings, or the earlier lignum vitae bearings.

I simply fit a spout underneath it to catch the drips, which diresct them into a small square plastic box fastened down with rubber straps for easy removal. One then can empty it once in a while, or if the drips are more continuous, put a float switch and small bilge pump such as a Johnson in the sump--in my case it was just a plastic storage box, with the hose led to a discharge overboard through-hull fitting just below the deck shelf and well above the water-line.

OR--you could fit one of those drip-less seals.

[Ryban]

Yeah, alignment could be an issue, but I'm nowhere near qualified enough to know for sure. Everything seems pretty well aligned, and the cutlass bearing isn't showing any wear.

Originally Posted by Mike Banks

Stuffing boxes are SUPPOSED to have a slight drip--because water is the lubrication for those plastic bearings, or the earlier lignum vitae bearings.

This is understood, but the issue is that there is no dripping coming from where the shaft enters the packing nut. Dripping only comes from between the threads that join the packing nut, to the male retainer if the packing nut is backed off. But in such an arrangement, the packing is not doing the job it's designed to do.