Stern gland packing

[castaway]

Having replaced the packing material in the stern gland on my Halberdier I am just looking for reassurance that I've not over tightened the 2 bolts.

After running the engine for an hour or so the the shaft in the area of the gland is just warm.... Any experts out there? Does that sound OK or should it be cold?

Anyway it doesnt leak any more!

Thanks Nick

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[ccscott49]

When you tighten up the nuts, the shaft should still be free enough to just turn by hand on the flange. The shaft seal, should drip a little when under way with engine and shaft turning. A drip now and again at rest is also acceptable, the seal area should be cold. IMHO.

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[longjohnsilver]

First time I changed my packing a few years back I overtightened the nuts so that the shaft became red hot!

Wot a plonker /forums/images/icons/frown.gif

I would have thought that just warm should be ok, but as you say cold is best!

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[johnsomerhausen]

The correct procedure is to tighten the nut (if it's a stern gland with a nut and "counternut") or the bolts by hand and then start the engine; if too much water comes through, stop the engine, tighten up half a turn, start the engine again and see if the dripping has diminished to the recommended 1-2 drops a minute. If not, tighten up one quarter turn again and so on until the desired result is achieved. This is of course for the traditional flax packing; there are now better ones available, such as the Goretex marine packing I use or the graphite impreganted packings.
john

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[trojan]

Be carefull using Graphited Packing. I was given some many years ago and after a season the gland leaks got worse and would not stop below a regular dripping - one drip a second. When hauled out and the shaft removed it was found to be pitted just where the packing was. A good indication of eloctrolosis on a stainless steel shaft. Graphite is very 'nobel' while stainless steel is still steel.

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[davidhand]

Funny you should say that but I used to design spillway gates etc. for hydro-electric projects, and graphite lubricated bearings caused pitting problems with stainless steel shafts. Bearing manufacturers changed their lube material, wouldn't say what to but I suspect it was teflon.

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[DMGibson]

What's all this talk about water dripping from stern glands? Don't you keep the stern tube filled with GREASE? A little of that shouuld then weep past the packing material to keep it lubricated, and minimise wear on the shaft and the packing.

Even if the outboard bearing is water lubricated, the shaft should be full of grease pumped in through the greaser fitted to the bearing. The grease may well get mixed with water, which is why it should be of the correct type - often called "Underwater grease".

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[rich]

Castrol underwater grease,states on tub, not to be used on sterntube, castrol heavy grease ok.

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[vyv_cox]

Under-water grease...

strangely enough, doesn't seem to work well too well in underwater bearings. It's only the soap that's insoluble, used to be a calcium based type but there are all sorts of strange chemistries now and I can't be sure. Under-water greases are intended more for static or very slightly moving components. There has been considerable research into this subject and the normal lithium-based soaps seem to work better in most wet bearing environments.

Personally, I use a bog-standard lithium-based Esso grease that I inherited with the boat. I've never changed the packing, more than 8 years now, and it never drips. I turn the greaser cap after every 2 hours of motoring. I adjusted the bolts once, after removing the shaft two seasons ago. The gland runs cold, not even the slightest bit warm.

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[Martin_e]

So does anyone really know what grease one uses. I live in Norway and looks as though I have got the Castrol grease that is not recomended though it does not say that on the scandanavian tube. I am running a rugular stern tube with an Volvo MD2 on one end. Maybe spannerman could come up with what is used over here.

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