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Stuffing box


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I'm sure this has been covered before. .. I want to repack the shaft Stuffing box with the boat in the water. I think I can do this because firstly I have a little packet of pre cut to my shaft size with tapered ends of Vetus gland packing and secondly because just behind the stuffing box towards the prop there is a permanently installed huge grease gun type thing for lubricating the bearings. The plan is to load up the shaft tube with grease which hopefully will prevent water ingress whilst I replace the packing.

However I like to own a motorboat and not a submarine so any advice appreciated.

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Hi Chris, yep, try this 

if you need time, you can block/tape the shaft to stop/slow the water ingress. You will get a bit of water in, but if you are reasonably prompt, it should not be too much....

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Well, what a disaster.

It would seem that the stern gland packing is too big. Firstly, it was very difficult to push in the packing, the only way was to compress the packing first with a pair of pliers and then force it in with a screwdriver. Running the engine for just a few moments in gear resulted in the stern gland being too hot to touch even with the end cap thing backed right off.

So, the packing is too big? Should the packing be a slack fit between the shaft and the stuffing box when you install it? The shaft is 35mm, the stuffing box is 45mm, so does this mean 5mm packing is required? The stuff I have on board is 6mm.

Got the feeling I should know all this stuff, but I don't.

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remove old packing with a hook,can be done in the water,looks a lot of water but its not,3 x packing is preferred and joins 90 degrees to each other,nip up till stops dripping when stationary,should drip when under way 1 of 2 drips per minute and should not be hot to touch.

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Yes,but since you can buy packing in 1mm increments, is there some formula that determines the right sized packing? What the previous owner gave me and what I tried to install was way too tight.

I measured the gap between shaft and stuffing box by using the back end of a twist bit. A 5mm twist bit will slide in, a 6mm bit won't. So 5mm is the packing required? Or quarter inch, 4.75mm packing, also available. .. Do you have to make any allowance for compression when you nip up the end cap thing?

I'm not trying to over think this, just get it right. Especially since I'm laid up in Verdun France and have to order the stuff from Holland.

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Hmm if the previous owner had 6mm packing onboard then I would think it is the correct size,why would you carry the wrong size??Is there anyone nearby who could have a look or advise??

 

Side track here but why would a japanese car have 10mm nuts and then put a 3/8th on number 7?

 

without trying to be silly here but have you looked at replacing with a dripless gland? If you intend on keeping/cruising for a number of years, There is serious on tv (sky)about various canals around Europe,looks like could be a bit of me in retirement yrs 

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There is a reason why the owner had the wrong sized packing - Vetus sell packing in little blister packs cut to length to suit the shaft diameter but with no consideration as to the gauge. By default their 35mm packing is 6mm square which is why they say here Vetus acronym - Very Expensive, Totally Useless.

All I want is to order some gland packing so I can get the he'll out of Verdun. So to recap, is 5mm packing what you put into a 5mm gap.

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Get a hammer and flatten one side of the packing until it slides in,, stagger the joins, as the packing should be "loose" water will run/drip in, nip up the gland until it "just" stops dripping. Rotate the shaft by hand to ensure it doesn't bind, Run motor at idle it should drip several times a minute. stop engine, dripping should stop. do not over tighten as this will glaze the packing and it will run hot, which hardens the packing, which is the last thing you want. There are several types of packing but the installation principle is pretty much the same.

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Thank you all.

With the 6mm forced into the gap the shaft was too stiff to turn by hand, even without the backing nut on so obviously the wrong size. Will order 5mm packing which by measurement is the right size to slide in.

There is not a single ship Chandler in France. Unbelievable!

So will have to order from Holland and try and find an address to which it can be posted for me to collect. Difficult since the old 'Post Restante' is no longer an offered service by postal agencies. Just as well Verdun is an interesting city to idle away a couple of days..

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Yep, used to sail once with a chief engineer whose favorite expression was 'don't force it! .. Use a bigger hammer.'

Always amazed me that he kept the engine running.

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This job is starting to get on my nerves.

5 days delivery time for the gland packing so I though I'd try the hammering it flat idea.

So a bit of careful whacking with a hammer reduced the packing to 5mm and it nicely slipped into the slot. Withe the engine running got 10 drops/minute with the compression thing backed right off,and with a little tensioning of the two bolts got it down to 3-4 drops/minute. After a few minutes the flow of water stopped and the stuffing box started to heat up, even with The compression thing backed off again. The only thing I can think of is that the gland packing doesn't like being whacked and gradually reverted to its original dimensions

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packing has no feelings,  ;-)  it is pressed into the square shape in the first place, you only altered the shape from 6 x 6 to 5 x 7 + - , How many rings have you inserted? are all the old rings removed? If there are 4 or 5, remove 1 ring and don't apply any "pressure" oh the compression plate, run the motor and monitor it,  allow more dripping, It will settle down. how hot, can you keep your hand on the gland?

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All the old packing was removed and the shaft and stuffing box cleaned up with a cloth. Three hammered rings of packing installed with staggered joints - all slipped into the space easily. The compression thing is in place but the two bolts have not been tightened.

On the stuffing box behind the where the rings would be there is a grub screw. If removed water will bubble out but not one drop will come through the packing. Checked with a paper towel placed beneath.

Gearbox is I think 2.8:1. At 1400 engine rpm in gear I can keep my hand on the shaft and stuffing box comfortably after 10 minutes running. Normally cruise at 2200 rpm.

Would like to see a drop or two of water though.

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Would like to run the engine at 2200 rpm in gear alongside so I could shut down if the stuffing box overheats, but the jetty we are fast to is not the best...

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All good now, got hold of some 5mm packing which I have just now installed and is delivering the desired 3 drops/minute, adjustable by the tension on the two bolts holding on the compression thing.

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