Question about drips and shaft packing...

[RobH2]

Yet another "shaft packing" thread but I need to pick some or your expert brains. My A4 has been running so well the past few years I've been pretty absent from the forum.

Last week I noticed my bilge pump running every 10 minutes and thought, "oh no, leak, sinking, distaster," etc. Turns out, my packing nut had a small stream coming out instead of drips. So, I replaced the packing.

I tried to get a 2-3 drips per second. But, by turning the nut only 1-degree or so either way, I got like 20-drips or zero drips. After a few tries, I got about 10 drips per second so I locked it down and ran the engine for a few minutes in the slip. When I stopped the engine, I had no drips. So I repeated the process. Again, when I stopped the engine, no drips. I could not physically crawl upside down under the fuel tank inside the lazarette one more time. It's not something a 65-year old is really capable of...lol... So, I left it, 1-degree from dripping, but, not dripping.

Questions: knowing that I'm merely 1-degree of a turn away from drips, but have none now, will I damage my shaft by running? Should I leave it and expect that the packing will likely loosen and I'll get a drip?

I measured the temp and it only got up to 114° on a 90° surrounding temp measurement running at full RPM for about 5-minutes.

[Dave Neptune]

Rob, did you use synthetic or flax packing? If you used synthetic you are probably OK, however keep an eye on the packing temp on the next few trips.

If you used a flax packing I'd definitely want to see a drip both running and all cooled off when sitting in the slip. Flax style packing will require some adjusting after installation for many trips. The synthetics will also require some minor tweaking but should settle in rapidly by comparison.

I installed synthetic and did not touch it for many many years once it settled after a couple of trips, really good stuff. It handles higher temps much better. The flax style sealer will run out as it thins at higher temps.

Dave Neptune

[RobH2]

Hi Dave,

I used WESTERN PACIFIC TRADING PTFE Flax Shaft Packing from WM. I guess that's considered synthetic. I didn't use the GTU Gore Packing (I think by Western Pacific Trading as well) as it was out of stock and I had a sort of emergency.

I also saw a post on the web where a guy suggested "feeding" it he called it. He put Syntef Shaft Packing Lubricant on each strand to help it and to transfer heat, as he put it.

Edit: I'm reading more and I think what I used is not synthetic and is the standard flax, it just has PTFE in it. Is that correct?

[Al Schober]

How many rings of packing did you install? I went to 2 rings with the cuts spaced 180 deg.

[RobH2]

That's a great question Al. I used 4. That's what searching on Google does for you. I watched a very good video and the guy said his normally took 1/4" packing and 3 of them. He suggested using 3/16 and using 4, so that's what I did. I could go back it off and pull 1 or 2 out though.

So 2 really does it? What's the advantage of fewer, that it allows a little leak better?

[Dave Neptune]

Various packing glands use different sizes of packing. That is why there are various sizes. Check to be sure what size you need and then do it over and I suggest the Gore or another synthetic. The cuts in the rings of the packing should be staggered and cut at an angle to alleviate leaks in the gaps.

Dave Neptune

[RobH2]

Sure, of course that's why it comes different sizes. From what I read, the right size should be able to be pushed in witout too much force but should not be sloppy. Once the packing is around the full circumference and consuming the space between the shaft and the inside of the gland it should be firm but not oversize. The 3/16 I used fit nicely, had some friction top and bottom but did not need brute force to push it in.

I must have really hammered in the original 1/4. And I don't think that's proper. From what I read as well, you want some room for the squishing of the gland to force the packing up and down to fill in.

I think I have a good size flax. But, I have ordered some Gortex and I will replace it. It's just so hard to get to and I'm not a spring chicken anymore. I was wiped out the rest of the day from having done that one task...lol... But, I think I'd feel better if I did see a drip.

[joe_db]

If you have a FLIR camera or IR thermometer, you may want to run some at high RPMs and see how hot it gets.
I have had a carbon face seal (PSS) for ages, so this is not an issue for me anymore. We used to just grab it back in the day to see if it was heating up.

[capnward]

I seem to have one of the few boats with the stuffing box on the outside. This of course makes it difficult to tighten it or replace packing while in the water, but apparently it was standard practice in 1948.
I assume the advantage to this is if you overtighten the stuffing, the heat that is generated is dissipated in the water.

[RobH2]

If you have a FLIR camera or IR thermometer, you may want to run some at high RPMs and see how hot it gets.
I have had a carbon face seal (PSS) for ages, so this is not an issue for me anymore. We used to just grab it back in the day to see if it was heating up.

Hi Joe, yes, I have an IR thermometer and I ran hard in the slip for about 10-mins and it got up to 114° with an ambient of 90°, so about a 24° differiential. I've read that about 20° difference is expected and normal. So I'm not far off of that even without a drip.

[RobH2]

I seem to have one of the few boats with the stuffing box on the outside. This of course makes it difficult to tighten it or replace packing while in the water, but apparently it was standard practice in 1948.
I assume the advantage to this is if you overtighten the stuffing, the heat that is generated is dissipated in the water.

That's really interesting. I wonder if that practice is still in use on any modern boats? Seems like a good way to go but there must be some downside if it's not common anymore. Maybe is was as simple as it was just difficult to maintain in the water. You had to go for a dive to mess with it.