stern gland Stern gland issues

[kalees]

Afternoon all,

 

I have 2 issues that I am trying to deal with. Firstly, a noise coming from the stern gland which can only be described as a chirping or squealing, not harmonic. As I was concerned with this, the first suggestion was to repack the stuffing box, so I had this done and this was with packed with 1/4 packing even though the original appeared to be 5/16, I was to that this was used as this style of stern tube was difficult to pack with 5/16, I believe this to be a Roy Willerby stern tube etc. When this work was carried out, the boat was in the water and not one drop of water came into the bilge.

 

As this made no difference, I had the boat slipped and checked over, there was no play in anything, the prop is perfect and when turning the shaft slowly, no sign of any noise or grinding etc. There was not time to draw the shaft as the slip was required and this was just squeezed in for a check.

 

As a suggestion, the stuffing box was repacked with 5/16 but had to be hammered flat to get in.

 

2nd issue, the stuffing box appears to be running hot, when I say not, I can hold my hand on it after a good run, but only just. I have tried to back off the nut but this does not seem to make any difference.

 

Questions:

 

Has anyone had any experience with this stern gear and had any unusual noises to deal with?

 

Is it possible that the nut has been too tight and despite backing the nut off, the packing is already compressed too much?

 

Appreciate that I am trying to deal with 2 issues at once here but any advice / suggestions would be truly greatfull

 

Keith

[Tony Brooks]

You should measure the gap the packing fits into. Use drills as gauges.

 

The packing is too tight, it should not run any  more than warm. When correctly adjusted the gland should drip up to twice a minute until you use the greaser. You should be able to turn the coupling by hand.

[kalees]

Hi Tony,

 

Regardless fo the adjustment, the shaft spins freely and I do not see any drips which is why I am wondering if it has been too tight and is stuck there. Good point about using drills as a measure, would this still apply on this system given that the packing has to pass the thread in the tube?

[kalees]

Forgot to mention that I also have grease coming in past the nut, I am guessing that this is due to the grease getting hot and thinning down.

[Tony Brooks]

1 hour ago, kalees said:

Forgot to mention that I also have grease coming in past the nut, I am guessing that this is due to the grease getting hot and thinning down.

 

A stern gland will run hot if the engine has dropped on its mounts. It typically pushes the shaft down onto the base of the gland nut and front bearing, so check the shaft alignment. Often grease leaks from the front of the gland when the packing is getting worn/loose.

 

The female thread in the tube is almost certainly cut into the tube bore, so the drill trick should work. Otherwise, use calipers to measure (a) the od of the shaft and (b) the id of the packing aperture. Take A from B and halve it. That is the packing size.

[kalees]

Thanks Tony,

 

I am now wondering if this could also be the cause of the noise. 

 

I will look into checking the alignment 

[Tony Brooks]

Check the engine mounts. The big nuts if they are that sort. Tighten bottom nuts up to the top ones. Also check the bolts holding the mounts onto the beds

[Steve56]

What sort of noise are you getting. Could it possibly be a singing prop.

[kalees]

Hi Steve,

 

It is not harmonic so I am fairly sure that it is not a singing prop. It is more like a squealing bearing.

[Tony Brooks]

45 minutes ago, kalees said:

Hi Steve,

 

It is not harmonic so I am fairly sure that it is not a singing prop. It is more like a squealing bearing.

 

Just an off the wall thought. Although with  a greased front bearing it should not be, but is there any chance you have a Cutless rubber back bearing or maybe a nylon/paxalon one. With no  water feed from the front either might squeal or chirp.

[kalees]

Hi Tony,

 

No cutlass bearing although I could not comment on the others. The noise that we hear, we have heard on other boats coming by so maybe it is just an anoying feature of this set up! 

 

Have you had much to do with this make of stern gear, if so, is it possible that it is just an anoying feature?

 

Re the stuffing box, I have just spent the morning replacing the packing myself this time. I used the drill trick to measure and 5/16 is correct so this has been used. I cleaned out all of the old black grease as much as possible and re-packed with 3 wraps of 5/16.

 

I have just run in gear on the ropes for about 20 mins and (in the image) green tube is warm or a liitle more than but the brass nuts I would say are hot.

 

I checked the engine mountings as sugested, bottom nut to top and they seem fine. I have not had a chance to check for further allignment as the engine is now hot and I did not want to change 2 things at once to enable a correct diagnosis.

 

When cleaning out the box there was still no water coming through and I have not seen any while running. When adding the 3rd wrap, I have only taken the brass nut in about 3 threads and the shaft spins freely. 

 

Putting my hand down the weed hatch, I do have grease coming out at the prop end of the shaft.

 

Keith.

[kalees]

Just a further thought on this, is it possible that the 3rd wrap is too tight because it will still be in the threaded area of the tube where the first 2 are past that point. Dont really want to tighten it right up to push it further in without further advise just in case this damages the packing that I have just fitted and I have no more with me at the moment?

[Tony Brooks]

The ID of the threaded section will almost certainly be the ID of the packing tube and a fraction larger than the OD of the pusher so I don't think the thread has anything to do with it.

 

The hot brass nuts suggests the engine mounts have collapsed and the shaft is being pushed down onto the bore in the nut. Time to take the coupling off and check the radial alignment.

[kalees]

So... after a frustrating afternoon undoing the wrong bolts on the Centa flex coupling, I undid the 8 that hold the coupling together and not the 4 from the gearbox, who knows what I was thinking!!!!

 

Alignment appears to be spot on but the Stuffing box and nut still appear to be getting hot, not quite sure what else it could be?

 

Regarding the Centa flex coupling, it has taken a lot of bolting back together as there appeared to be surpless rubber around some of the edge so have had to keep going around the blots tightening them up. Will this be an issue in the future, do I need to replace the coupling?

[Tacet]

My dad had a Hurth on his boat; rather unreliable even after being exchanged.  Being the mend-anything (and spend nothing)  sort, he took it apart and found that wear in several parts meant lost motion in the engagement.  Spent ages on his lathe creating a complicated eccentric to make up for the lost motion - and was feeling quite pleased with himself when it all worked nicely on the bench.

 

Final stage was to harden the camshaft - for which he used an ancient tin of case hardening powder and his solid fuel fire.  Not so happy when he found the hardening process had shrunk his gadget such that it no longer engaged the gears.

 

Like Tony - I would be looking to see if it can be changed for a PRM

Edited May 30, 2022 by Tacet

[Tracy D'arth]

1 hour ago, Tacet said:

My dad had a Hurth on his boat; rather unreliable even after being exchanged.  Being the mend-anything (and spend nothing)  sort, he took it apart and found that wear in several parts meant lost motion in the engagement.  Spent ages on his lathe creating a complicated eccentric to make up for the lost motion - and was feeling quite pleased with himself when it all worked nicely on the bench.

 

Final stage was to harden the camshaft - for which he used an ancient tin of case hardening powder and his solid fuel fire.  Not so happy when he found the hardening process had shrunk his gadget such that it no longer engaged the gears.

 

Like Tony - I would be looking to see if it can be changed for a PRM

I think you may have replied to the wrong thread?  Interesting though, thanks.

[Tacet]

3 hours ago, Tracy D'arth said:

I think you may have replied to the wrong thread?  Interesting though, thanks.

Yes - sorry.  Not sure how I did that.

[Marko J]

Hello to everyone. I read all this about strange sound from stuffing box or stern gland and found it's similar like mine problem this days. When engine is powered in gear, and forward, strange harmonized squeak is coming from stuffing box. When going backwards - nothing. When idle, even high revs - nothing. That problem comes with no drips. I didn't inspected heating. 

Some ideas of what could it be are welcome. Thanks

 

 

Here is the video I've made. (Don't ask me about bilge, its BMC 1.5 :D) 

 

 

[Tony Brooks]

Does it have a greaser, the photo is too indistinct for me.

 

What is the gap between the front of the prop and the back of the rear shaft bearing housing?  Is there enough movement in the rubber engine mounts to allow the prop to contact the bearing housing in ahead - look down the weed hatch.

 

Is the shaft going into the gland through the centre of a perfectly round hole or is the shaft slightly offset or is the hole in the gland egg shaped or oval?

 

Can you turn the shaft by hand with the engine off and in neutral, if not the gland might be too tight. Try twisting the coupling.

 

At the end of a day's cruise does the gland drip a very small amount until the greaser is used to seal it? If not, the gland might be too tight.

[Marko J]

4 minutes ago, Tony Brooks said:

Does it have a greaser, the photo is too indistinct for me.

 

What is the gap between the front of the prop and the back of the rear shaft bearing housing?  Is there enough movement in the rubber engine mounts to allow the prop to contact the bearing housing in ahead - look down the weed hatch.

 

Is the shaft going into the gland through the centre of a perfectly round hole or is the shaft slightly offset or is the hole in the gland egg shaped or oval?

 

Can you turn the shaft by hand with the engine off and in neutral, if not the gland might be too tight. Try twisting the coupling.

 

At the end of a day's cruise does the gland drip a very small amount until the greaser is used to seal it? If not, the gland might be too tight.

Thanks for fast reply.
1 - It's greased properly, but I think I mistakenly greased air breather too last time. 
2 - I will check for engine mounts. In may 2022 I did total engine rebuild. Maybe mount got loose.
3 -  Since I didn't had problems with shaft before I must check for gland egg shape too. 
4 - Shaft can be turned by hand when engine is off. 
5 - I will check for gland drip too. 

[Tony Brooks]

8 hours ago, Marko J said:

1 - It's greased properly, but I think I mistakenly greased air breather too last time. 

 

For the gland shown, as far as one can see in the photo, that makes no sense. So we need a clear photo of the gland and whatever is behind the brass section. Also what type of boat is this. It looks as if the shaft might be in a bit of a keel.

 

I am sure that it is a packed gland, so that means it needs greasing BUT if this is a steel/GRP/wooden cruiser AND the gland fits into a large rubber hose at the back then it is possible the shaft bearings are fluted rubber Cutless bearings. If so they need a supply of water to lubricate them. If you greased the breather, then you may have sealed it, so no water can get at the front bearing. On our cruisers with that sort of gland where there is a breather on the Vetus style glands, there was a small water pipe fed from the raw water pump on the engine. When the raw water supply was restricted, sometimes we would get a squeak similar to yours from the bearing that was in the stern tube just behind the large hose. Depending upon shaft length there may be on, two or more Cutless bearings in the assembly.

[Marko J]

Its a Dutch steel motorcruiser boat 7.8x2.6 meters. After I greased closest greasing points and degreased air breather, I did some other checks: 

- Engine mountings are ok

- I can turn shaft by hand relatively easy

- No leaks 

- After one hour of boating on 1500 rpms and more, stuffing box, shaft and other parts stays cold  - no signs of heating

 

 

Here are the photos of the system.

Stil I wonder what is the purpose of the third greasing point, the one far away from the transmission (its on the top of 1st photo)? 

 

 

[Tony Brooks]

I suspect you may well have cutless rubber shaft bearings, so without a vent or positive water supply to them that may be the squeak. Especially if it seems to go away at higher speeds

[Marko J]

I don't know, this is rear section

[Tony Brooks]

Hard to say. If you can push the prop and shaft from side to side and/or and the shaft moves a little, but without any knock, then it may well have rubber bearings. If it knocks as the shaft hits the bearing, then it is unlikely to be a rubber bearing. What I can say is they the fitting that seems to screw onto the back of the stern tube does not look like the type that typically contains a Cutless bearing, but we don't know what is in the back of the tube.

 

More thoughts, it looks as if there is a grease nipple close to the back of the stern tube. That and the two at the front do suggest that it has plain metal bearings. If that is the case, there is every chance the whole of the tube needs filling with grease, so it gets forced to the back bearing. The trouble is that doing that with rubber bearings will not be a good idea. I think that you may have to find a yard that specialises in Dutch cruisers to find out what is common practice shaft & bearing wise.

 

If this were a wooden boat, then that third greaser would most likely (see how I can not be definite) would be to fill the gap in the shaft log between the stern tube and the sides of the hole in the log with something to prevent water leaking into the boat between the log and tube, but I don't see how this can be the case with a steel boat because there is no log as such. The only logical thing is that it somehow greases the back bearing, but there are no signs of grease exiting the aft bearing in your photo.

 

Sorry, I don't have enough experience of such boats to say any more.