stern tube packing

M

monkey_trousers

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bf494.co.uk
currently 2 to 3 drips a second, so toying with idea of either drilling and tapping the stern tube to fit a grease nipple then giving it large with the grease gun or (takes deep breath) loosening the thinging off and shoving some more packing in - whilst its sat in the water!

good bad or just plain stupid an idea(s)
 
going to brave it this weekend, should of done it when she was last out the water, bit will have a go and hope I don't get too wet in the process.

any recomendations for packing material?? PTFE versus Graphite?
 
Can you lean anywhere and do it while the tides out ? Dunno how much flow if you try it afloat; I'd be imagining trying to keep the packing in place and screw nut back on while leak floats it off. I'll be replacing mine with the ptfe when the time comes.
 
I know logic says... do it dry, but......

the cutlass bearing on the outer end is in good shape, so hopefully not to much water...

we've been attacking the engine room in a big way, and it would be nice to get it to a position where we can keep it as dry as possible to finish off
 
The packing really needs to be proper Gland Packing. This comes in various sizes [ie, thicknesses] depending on the difference between the diameter of the shaft and the inner diameter of the tube. The only gland packing that I have seen is impregnated with either graphite or lanolin, but it wouldn't surprise me if it is available impregnated with PTFE. Once you have everything re-assembled, I'd give it some welly with a grease gun to make sure that all the little mysterious spaces that the packing doesn't fill are filled with grease.
Peter.
 
mysteriously, there is no grease nipple to be seen on the stern tube at all. Only done this once before on a narrow boat years ago, used graphite impregnated packing rope back then but have heard that ptfe is now available
 
I reckon three rings of new packing, cut to size, space the gaps in the rings at equal points around, christ, that was a crap descriptoin, I mean place the joins at 12, 4 and 8 o'clock, still not much better!

I'd do it wet, but have a back up plan!
 
when yopu cut the packing, cut it at 45 degrees, so it doesnt have a direct path for water and stagger the joins at 60 degrees around the stern tube. grease well when fitting and tighten nut up. You dont need a greaser. (but handy if you have) put one in next time she comes out of the water, not just a grease nipple, a proper brass screwdown grease reservoir, much easier.
I do mine afloat and have had no problems.
 
Hi,
[ QUOTE ]

the cutlass bearing on the outer end is in good shape, so hopefully not to much water...


[/ QUOTE ]
So you have cutlass at the back end, a packed gland on the inside, is there any thing in between? If not, then a grease nipple and grease is probably not a good idea, all you will do is fill your cruising ground with oily pollution as the grease squeezes out through the cutlass bearing.
If you are going to do it afloat, move her up the beach, and rehearse everything before pulling the old packing out of the gland.
 
Graphite is the most noble on the galvanic scale so corrodes everything it comes into contact with. Use anything but graphite! And as already said, use the correct size packing otherwise it won't work. Additional grease is not needed. Many boats have no greaser.
 
[ QUOTE ]
going to brave it this weekend, should of done it when she was last out the water, bit will have a go and hope I don't get too wet in the process.

any recomendations for packing material?? PTFE versus Graphite?

[/ QUOTE ]

7 yrs ago i changed the engine gate valve /forums/images/graemlins/ooo.gif
AFLOAT /forums/images/graemlins/cool.gif
 
ok, so what happened!

the pusher was not even hand tight! (D'oh!) but I stripped it, peeped down the shaft at the packing, thought thats nice, shove the pushed back in and did the bolts back up just a fraction over hand tight..

no drips!

least the excercise let me know wht size packing to buy in anticipation. The acid test will be this weekend when we're taking her out for a run, (attention all shipping sea area Tyne!) see whether the leak re-appears

then I'll proper do it

if its remains ok, it can stay as is, and I'll do it in february when she's coming out, for a few repairs and a recaulk
 
As a bearing supplier who works with a stern gear supplier who has been in the business for years in Western Australia, their advice from experience is.

Grease is not needed, water is not only a good lubricant but also a good conductor of heat. The packing is what seals not the grease.

Dangers of using grease are temperature increase and if used to excess blocking of water channels in the cutless bearing aft of the gland. This can cause the bearing to fail.

They are very surprised that we see so many stern glands with grease over here, it's almost unheard of over there, with plenty of boats and stern tubes.

However you will hear lots of people in this part of the world who swear by a squirt of grease evertime they stop, my father included!
 
Traditional greasers even say it on them "One turn per hour".
Does it depend on the type of grease? Are ordinary multi-purpose greases unsuitable because they don't emulsify with water?
I have a pre-war tin of Castrol Water Pump grease, a kind of waxy orange colour, which presumably was designed for a somewhat similar situation.
 
Its just what I have learnt since working with the australians and bearings. Grease would seem to be completely unnecessary. Stern glands work perfectly with water as a lubricant/coolant that should allow the packing to last longer as the shaft runs on a thin film of water, dripping slightly whilst turning and not dripping when stopped.

I suspect the fine tuning of this is what made someone start using grease in the past. But the Australian factory has hardly ever seen grease in use in the past 10 years for stern glands.
 
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