Packing Size--A Question for the Experts

1984 Ski Nautique 2001
Engine Model PRD WR R10
Pleasurecraft Marine
Right-Hand Rotation from Rear
351 CID -- 255 h.p.
Warner Velvet Drive Model 10-17-003
Direct Drive (1:1)



I've read the million and a half threads about packing boxes and packing size. :) I still think I need to ask you guys about mine.

Today I packed the driveshaft packing box on our new (to us) SN2001. This is the first time I've packed a packing box.

The previous "packing" was a mess. I counted 11 full turns of the gland nut before it came off, and found some super-thin white plastic type stuff spiral wrapped (5 spiral turns). This stuff was thin as teflon tape in most areas. No wonder the box was leaking like a sieve.

I made sure I had all old packing out. I tried to measure the packing size I needed. The nut was loose on the shaft, and I was able to insert a 1/4" drill bit (chuck end) on one side and a 15/64" drill bit (chuck end) on the other side, almost 180 degrees apart. So I concluded that the gap was about 15/64", and so 1/4" packing would be appropriate.

I also measured the nut movement allowing for 4 threads engagment--there was 3/4" left, so I figured that meant 3 rings of 1/4" GFO.

I had plenty of Gore Tex GFO on hand, both 3/16" and 1/4". Using a 1" wooden dowel as a pattern for my 1" driveshaft, I cut a ring of 1/4", following the method described in the tutorial linked from some other threads on this forum. The ring was impossible to push into the nut gap. I believe I cut the ring too long, so I cut another ring, allowing for some squeezing down of the ring--still would not push into the gap (even pushing very hard). I then worked with a shorter ring of 1/4" GFO, using my thumbs to squeeze it down onto the dowel, getting a perfectly closed ring, which was now about 3/16" thick (driveshaft radially) and about 5/16" wide (driveshaft axially). This would push into the nut, somewhat, but it took a *lot* of force and because the rings were widened, only two rings would fit into the nut. And I could not get them well inserted and seated against each other--too much friction. I felt like there were big gaps inside because the rings were still very hard to pack in. So I pulled them out and switched to 3/16" packing.

I cut the 3/16" GFO to perfect size on the dowel without squeezing each ring down onto the dowel. These rings packed into the gland nut easily--almost too easily. In fact, the nut still wanted to slide itself down the inclined shaft with the first ring inserted. I figured 4 rings would be right (4 x 3/16" = 3/4", which should leave me 4 threads engagement). Once I got the 4 rings pushed into the nut, it wasn't so floppy on the shaft.

I started the nut on the threads and counted revolutions--I lightly contacted the packing at 2 revs. But, (i) I should have had 4 revs if the rings were pushed just snug to one another, and (ii) if I wiggled the nut and threaded cylinder up and down it (very) easily would go "tap tap tap", with the hole edge of the gland nut touching the driveshaft. That last item, the "tap tap" struck me as wrong--I don't want the shaft (even though I've seen no whirling) getting grooved on the gland nut.

So... I tightened the gland nut further. It turned *very* easily, and it felt like it was lightly "seating" the GFO rings. At a total of 4.25 turns (from initial thread engagement), the nut became noticeably stiffer, feeling like the rings were now seated against one another, and light pulling on the nut would not give the "tap tap tap". If I pulled harder on it, I could make contact, but given the hose mount, I suspect that would be normal.


My apologies for getting longwinded on this... given the story above:

(1) Do you think my packing box should use 1/4" or 3/16" GFO?

(2) Was it appropriate to continue tightening the nut until the rings seated against one another?


I'm still not sure why the rings weren't seated when I pushed them in.

I'll know more once on the lake. Either the 3/16" will leak like a river, or they will smoke out in the first hundred yards due to my tightening.

If no great problems, I plan to run at this setting for about 2 hours of shaft-turning time, then adjust for drip rate and temp (15-20 degF above lake temp), then run more and do it again. After a few days of adjustment, when I'm sure it's dialed in, I'll safety wire it.

btw, I also added a nice access hatch to the removeable floor section. My '84 would require pulling the doghouse, the rear seat and the floor to observe the packing box while in motion. I'm much happier with the access hatch. Mine is rectangular while the later years came with a round hatch, but I like it because I may be able to get in there with wrenches through the hatch.

Thanks in advance for your thoughts about this.

Steve

Wow, great point. I actually hadn't thought of checking it before launching off the trailer. Will do! (Actually, the son is much better at climbing on trailers and boats like a chimp than the old man these days, so I'll have him do it.)

Thanks, Chris.

Steve

Well, we were on the water for a week and the verdict is... I'm not sure.

I had plenty of other issues with the boat I dealt with to keep it running (about 3/4 of the time) for the kids. The previous owner(s) left me with a lot of problems. That's ok; we'll work through them and end up with a reliable boat.

When the boat went in the water after the packing described above, the gland nut was leaking a strong steady stream. Now, I know the best thing to do was to run the boat for 2 hours of shaft turning time and then check the box... but it was a windy, wavy day and the boat made the short trip to the dock only. (Thankfully all the other vacation days were fantastic.) I didn't want the bilge pump running often and running down the battery, so I ended up turning down the gland nut by hand a bit at a time... ended up adding about 1-1/8 more turns before the dripping slowed to maybe 4 to 8 drips per minute.

I was sure I would smoke the packing, but when we ran it, some days it didn't drip much at all, some days it dripped 4 to 8 drips a minute, and the packing box never got very warm to the touch, I doubt more than 15 to 20 degF above lake water.

Bottom line: I need more water time with this packing to decide if I need to re-do it.

Sounds like it is fixed as is.

From what I read about the reunions, they enjoy this (troubleshooting and repairs) just as much as being out on the water. I would definitely try to get there for some expert tech support.