Adjusting the stuffing gland

[nb maggie]

Hi all,

 

I need to tighten the stuffing gland on Maggie as it has started driping a little. I assume I tighten the two screws marked with arrows in the photo below.

 

 

How much do I tighten them?

[Big COL]

Hi all,

 

I need to tighten the stuffing gland on Maggie as it has started driping a little. I assume I tighten the two screws marked with arrows in the photo below.

 

 

How much do I tighten them?

<{POST_SNAPBACK}>

 

 

NB Maggi

 

With the gearbox in neutral, you should be able to turn the shaft, tighten both nuts equally until the shaft becomes tight and is quite hard to turn. Then back off the nuts a flat at a time until the shaft becomes eaiser to turn, there should be a little resistance when turning the shaft, You should be able to judge the difference in the shaft from how it was before you started to how it is now, the adjustment will have added some resistance when turning. The principle is the same as if you were adjusting a taper bearing. If you run out of thread and cannot adjust the gland any more and the shaft still turns freely, and the gland still drips, then you will need to repack the gland with some new packing.

Edited May 3, 2005 by Big COL

[Yamanx]

How do you do that?

[DHutch]

How do you do that?

How do you do what?

- tighten the nuts

- put the box in neutral

- turn the propshaft

[bottle]

Daniel

 

I think he wants to know how to stuff it, sorry re-pack it.

[DHutch]

I think he wants to know how to stuff it, sorry re-pack it.

Ah, that would make sence Doh!

 

- Urmm well, from what ive heard, you get a big bilge pump, screw down a load of grease, undo the bolts, take off the plate, whip out the old packing, and stuf in the new. (there a usally three sets of packing)

 

- Also, if you're just trying to get another season out of it you can add one more ring of packing on to the old.

 

 

Daniel

[Big COL]

How do you do that?

<{POST_SNAPBACK}>

 

Hi Yamanx

 

Never actually changed the packing on a boat, have done lots on pumps including pumps with flooded suction. The gland box is the same on a pump as on a boat . To change the packing live ( boat in water) you can expect water to come into the boat how much will depend on the amount of wear there is on the shaft etc sometimes there is no water ingress but it's advisable to have a good pump to hand just in case.

To change the packing you need to cut the new packing to length lay the packing around the shaft and mark and cut where they meet, or if you know the shaft size then buy pre cut packing. Undo the gland nuts and pull the slide out of the stuffing box. To remove the old packing I use a long thin screwdriver that has the end ground to a point and bent at 90 degrees force the point into the old packing and hook it out then repeat to remove all the old packing. This is the point when the water will start to flow wrap the new packing around the shaft and push it into the stuffing box note the position of the joint, the second packing do the same as the first but rotate the join through 90 degrees, continue to do the same with the rest of the packings rotating the join each time. It's important to have the joins off set as if they were in line it leaves a open path for water to pass through. When the last packing piece is in push the slide home and just start the nuts, then wind the greaser down two or three turns and spin the shaft repeat with the greaser. Then adjust the gland as previously described, when adjusted wind the greaser down and run the engine in gear while its running turn the greaser down if required. Keep an eye on the gland as you will find it may need adjusting again as the new packing settles down.

Edited May 3, 2005 by Big COL

[David Schweizer]

Hi Yamanx

 

  Never actually changed the packing on a boat, have done lots on pumps including pumps with flooded suction. The gland box is the same on a pump as on a boat . To change the packing live ( boat in water) you can expect water to come into the boat how much will depend on the amount of wear there is on the shaft etc  sometimes there is no water ingress but it's advisable to have a good pump to hand just in case.

      To change the packing you need to cut the new packing to length lay the packing around the shaft and mark and cut where they meet, or if you know the shaft size then buy pre cut packing. Undo the gland nuts and pull the slide out of the stuffing box. To remove the old packing I use a long thin screwdriver that has the end ground to a point and bent at 90 degrees force the point into the old packing and hook it out then repeat to remove all the old packing. This is the point when the water will start to flow wrap the new packing around the shaft and push it into the stuffing box note the position of the joint, the second packing do the same as the first but rotate the join through 90 degrees, continue to do the same with the rest of the packings rotating the join each time. It's important to have the joins off set  as if they were in line it leaves a open path for water to pass through. When the last packing piece is in push the slide home and just start the  nuts, then wind the greaser down two or three turns and spin the shaft repeat with the greaser. Then adjust the gland as previously described, when adjusted wind the greaser down and run the engine in gear while its running turn the greaser down if required. Keep an eye on the gland as you will find it may need adjusting again as the new packing settles down.

<{POST_SNAPBACK}>

Yes, that's exactly how the chap I payed to do it, did it. I was a bit concerned when he did it with the boat in the water, especially as it had been in dry dock all week, but there was virtually no ingress of water at all. I still wouldn't try to do it myself though, just in case.

[Yamanx]

Thank you for that information. I'll give it a try later in the summer. I seem to have run out of adjustment, at least it feels too tight and still drips.

[ChrisPy]

I suggest you sit the stern on a mudbank as a damage limitation measure before you start ....

[DHutch]

I suggest you sit the stern on a mudbank as a damage limitation measure before you start ....

 

LOL, i like you confidence!!

 

- Serously tho, pump plenty of grease in there and it should leak much at all (dont then turn the prop untill the job is done.

- Ive if the bearing is badly worn, there wont be more than a good bilge pump can keep up with.

 

 

Daniel

[Alan Saunders]

Have I understood correctly? You cut the packing into individual rings? I thought you just wound the whole thing in in a coil. I seem to remember something about making sure the coi tended to eject water in forward gear.

 

How do I determine what size/length of packing to buy?

 

Confused - Alan - (about to do this job)

[John Orentas]

Alan.

 

The conventional way, wind a full turn of the packing around the shaft then cut through both thicknesses with a sharp knife at an angle of about 30 deg to the line of the shaft. You will then have a ring a little larger than the shaft diameter, the idea is that the two ends will squeeze together with a sort of scarf joint. Cut 3 or 4 of these and fit into the recess of the gland alternating the joint by 90 deg.

 

Very little water will come through even a well worn stern tube. To find the size measure the shaft dia. then the inside dia. of the gland orifice, subtract one from the other and divide by 2. The most common is 8 mm. the section is always 'square'.

[Noah]

When I first repacked a gland I extracted a small piece of the old stuff with a small hook made from an old screwdriver. I then took the piece to a chandlery to find a match. To prevent water pouring in (as I imagined would happen) I reached down the weedhatch and wrapped a few turns of plumber's Denso tape around the shaft where it exits the stern tube near the prop. No water came in during the couple of hours it took me to pick out all the old packing and repack with new. I did have an auto bilge pump standing by though. I think any waterproof sticky stuff would make a temporary seal on the shaft from outside and prevents panic if you're doing the job for the first time like I was. It was a bit messy remove afterwards but I have had worse stuff down the weedhatch!

 

Noah

[Alan Saunders]

Thanks for that John and Noah. Was it necessary to remove the tape? Why not just leave it in place?

 

I reckon this could be a good topic to put in the 'articles' section.

 

Alan

[Noah]

Hi Alan

 

If I hadn't removed the Denso tape it would have probably unwound itself and got flung off the shaft when underway. However, I would'nt have known until then if my first repacking was successful and watertight!

 

I got a roll of this tape many years ago from a plumbers merchant when it was used for waterproofing gas pipe joints. It's foul stuff to handle but I've used it to make successfull temporary underwater repairs to canoes. It's possible that a handfull of jointing paste could be moulded around the outside of the stern tube with similar success. It only take a few minutes and gives more time to do a good job of the repacking.

 

Noah