Re: Changing prop shaft gland packing
You can have to much packing in the cap. If I remember correct they were only designed for 2 wraps. If you notice when you have the cap off the male end of the shaft log has a ( V ) taper,tapering in. So when you tighten the cap,which is flat inside, it forces the packing into the (V)around the shaft sealing the shaft. If you have to much packing. You must use a lot more force to tighten the cap to get it to seal. Also it could just bunch up in the cap and may not seal proper. Which could cause the shaft log to run off center. This is the case where more is not better.You should almost be able to tighten the nut by hand. Just make sure you have the correct size packing. Make sure you cut the packing on a 45 Deg. and put the cuts 180 Degs.from each other. Just because you can get more packing in the cap does not make it correct. The added threades and space in the cap are required to withstand the compression force on the seal and keep the threads from stripping. Bill
Re: Changing prop shaft gland packing
Quote:
Originally Posted by Trojan
You can have to much packing in the cap. If I remember correct they were only designed for 2 wraps. If you notice when you have the cap off the male end of the shaft log has a ( V ) taper,tapering in. So when you tighten the cap,which is flat inside, it forces the packing into the (V)around the shaft sealing the shaft. If you have to much packing. You must use a lot more force to tighten the cap to get it to seal. Also it could just bunch up in the cap and may not seal proper. Which could cause the shaft log to run off center. This is the case where more is not better.You should almost be able to tighten the nut by hand. Just make sure you have the correct size packing. Make sure you cut the packing on a 45 Deg. and put the cuts 180 Degs.from each other. Just because you can get more packing in the cap does not make it correct. The added threades and space in the cap are required to withstand the compression force on the seal and keep the threads from stripping. Bill
Trojan,
53MYs do not have a threaded cap. The cap is a collar with two threaded studs which have nuts to do the squeezing. GFO recommends 90 degree difference in cut placement. Your logic still applies though: more is not necessarily better. I'll use 3 rings like Genesis did.
Also, I think you're right that the whole packing is spinning, which is the cause of the wobbling gland when running.
Thanks,
Doug
Re: Changing prop shaft gland packing
a few comments/questions-
Back in the early 80's, one could buy the traditional flax/beeswax type packing or teflon impregnated. I thought the teflon sounded slick (yeah, pun intended) and specified it on a 4" shaft for a seiner. My thought was it should reduce temperature at a given squeeze force. Is the teflon still around? I had not heard of GFO- it must be slick as well...
On spinning the packing- This sounds odd to me. The shaft is smaller dia and probably smoother than the gland. Why on earth would the packing spin in the gland vs the shaft?
On wobble- If I had this, I think I would do shaft alignment at next haulout and strive to center the shaft in the log. I mean, alignment does not last forever, things settle and shift. My old sailboat auxilliary was out of line at some point in the boat's life and the shaft log was ovaled on the inside. The wall thickness was getting thin! Fix would have been a bitch as the log was a complicated casting that had the rudder hole integral.
Gary
Re: Changing prop shaft gland packing
In a previous post he said the log wobbled and the shaft was in line.That would seam to be the only logical answer. More like bunching of the packing caused by a loose nut or old packing left in it. I agree it would be odd. But there are stranger things. Bill
Re: Changing prop shaft gland packing
Found 4 packing rings in the shaft log. Also found the raw water intake seacock valves to be trashed. It's a real bear to remove the 2 1/2" seal nut, 5200 is tough stuff, it required a 4' pipe extension on a breaker bar to get enough leverage. I can report that the hull in the intake area is a full 1" thick.......and luckly found no delamination. mike
Re: Changing prop shaft gland packing
Mike,
Were you able to correct the alignment of the packing gland versus shaft and log? I don't know whether to try it on the rear (shaft log) side of the hose or the gland end of the hose. It seems like the shaft log side would adjust it better, but is that end pre-determined by the shaft log geometry instead of how the hose is attached? And do they put the shaft log hose on with some kind of sealer, making it almost impssible to move by just loosening the hose clamps?
Thanks,
Doug
Re: Changing prop shaft gland packing
Doug,
I have not got that far along, still working on fixing the raw water intake. But at first glance it appears that both hose ends will have to be adjusted on my setup. When I removed all the packing the log sat down on the shaft. There is a tremendous amount of down pressure from the log hose. It is very apperent that the hose connection and alignment is critical. I don't believe a sealer is used between the hose, log and gland. But if one is concerened you could use Merc-cruser bellows glue, I have used it with great success on my old TRS drives in my offshore sport boat. The only problem is you have to be high and dry to use it. By the way, 3" long sheet rock scews driven into the packing makes for a good removal tool. Drive one in and pry it out with vise grips,...works great, just make sure you bias the screw away from the shaft and toward the log body. Mike
Re: Changing prop shaft gland packing
So thanks to this group, I repacked both of my prop shaft glands today (wet) with GFO. It took 3 hours because "nothing is ever simple". They're practically drip-free after 2 hours of running and a little adjusting. I'll watch them closely for another few running hours in May. Here's some "Lessons Learned":
1. The water coming in is not bad. Maybe a gallon in 2 minutes. The bilge pumps keep up with it easily (Rule 2000 pumps).
2. Mike absolutely saved my arse from a much longer ordeal digging out the old packing by recommending 3" long drywall screws as extractors. It's REALLY HARD to get the old flax stuff out and I had made a few sharp bent pick things to try, but with the drywall screws you just screw them into the flax and grab them with a vise grip and pull. THANKS MIKE !!!! I tried my pick things and a dental pick but that stuff is WAY stronger and wedged in way tighter than picks can get out. Only problem was I wanted 4" drywall screws to get at that last layer at the far end of the gland.
3. GFO works great. I knew to cut it at a 45 degree angle, but I didn't know which way the angle was supposed to be (overlapping front to rear or overlapping outside to inside. So I alternated them in the layers.
4. The fit of the 2 collars keeps any misaligned gland angle from misforming the GFO too much. Mine is too close on the top and too far on the bottom, but the collar minimizes that.
5. You use the collar to push in each successive layer of new GFO. The studs are long so the nuts tighten the layers in just fine.
6. I found 4 layers of flax and the wobbling port gland had a 5th partial layer that was a wad. I think it was incompletely removed from the previous time it was packed and was spinning like a wad at the bottom layer. I put 3 layers of GFO back in.
7. Both glands still have an almost imperceptible wobble when running, like maybe a 32nd or 64th inch. I'm going to let it go and watch it. The hoses were clamped stongly and had not moved on the shaft log any (thanks Jim). I'll watch that too. If Mike is successful in realigning glands by adjusting his shaft log hoses, I'll try that too whenever I have it hauled but it's $500 to haul at my marina that I don't want to spend.
Thanks again,
Doug Shuman
Re: Changing prop shaft gland packing
They never run true true. That is why they use packing and a rubber boot instead of a seal or O ring with a solid mount. Glad you got it done. Another one under your belt. With stories like this. We will all start doing our own work. Sears have a regular packing remover kit. Bill
Re: Changing prop shaft gland packing
West has a corkscrew pick on a flexible shaft with a T-handle on the end that works well.
Screw in and PULL.
Just don't get a defective one. I had one that wasn't swaged together properly and the pick part came out of the barrel when I yanked on it. That really pissed me off, because I then had to go get another one, and had a piece of pick in there which meant I had to get that other one RIGHT NOW and take care of it.