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Tightening the Stuffing Box


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Hi All

 

The stern gland is leaking a fair amount (milky white water) despite tightening the greaser so I'm thinking its time the Stuffing Box needs tightening (it was fitted new before purchase). I'm assuming it needs regular tightening but I just wanted to check if there is a magic formula to use such as 1/4 turn on each etc.... any pitfalls?  Assume the worse thing is to overtighten so looking to do this right first time if I can!

 

thanks in anticipation

rob

 

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Ensure you tighten both sides equally 1 flat at a time each side. Ensure that you cans till turn the shaft by hand on the shaft coupling when done (not applicable to a Lister lLH150 gearbox).

 

Don't grease first and when done it should still drip  once or twice a minute and then stop when you use the greaser. However I normally tighten a tad more so the drip stops but when you use the greaser a bead or water or grease appears at the front of the gland.

 

 

 

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6 minutes ago, robtheplod said:

It was packed when the new bits were fitted before sale last month?  

 

Perhaps somebody has been telling porkies? Mine was done years ago and there is still loads of room for adjustment before it needs doing again (more than yours seems to have).

 

 

Edited by Machpoint005
for clarity
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Looking at the quality of workmanship of the job as a whole, you will probably need to add at least one extra piece of packing inside the gland and check the existing is thick enough.. A bare minimum of time and effort has been carried out on the installation.

Not even bothering to put primer over fresh joints(rust appearing already) , ground surfaces or removed metal, sikaflex oozing out of the external gland, and smeared elsewhere,....

 

You probably need to check what is in your greasing cylinder as well, and maybe replace if it's too thin.

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We have had Nightwatch for 14 years. We tightened, repacked the gland more times than I'd like to remember. Always grease it on a regular basis. Always had issues with it. Don't think there's owt wrong wiv it. More summat wrong wiv me.

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36 minutes ago, Tony Brooks said:

Ensure you tighten both sides equally 1 flat at a time each side. Ensure that you cans till turn the shaft by hand on the shaft coupling when done (not applicable to a Lister lLH150 gearbox).

 

Don't grease first and when done it should still drip  once or twice a minute and then stop when you use the greaser. However I normally tighten a tad more so the drip stops but when you use the greaser a bead or water or grease appears at the front of the gland.

 

Many thanks, I guess this is one of those things that you adjust/check until you 'feel' its right? Will do as you recommend.

 

36 minutes ago, Tony Brooks said:

 

 

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34 minutes ago, robtheplod said:

It was packed when the new bits were fitted before sale last month?  

Mines got half that space left and it’s still holding strong. 

 

I give each side a quarter turn until they’re both firm. I just use thumb pressure on the end of the spanner so I don’t over tighten. Seems to work for me. 

 

Sometimes it can be leak free for ages, then something hits the prop and it takes a little while to settle again. 

 

 

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1 hour ago, bizzard said:

Id you wish to get the packing pusher dead square on to the gland use the inner diameter prongs of a hernia gauge between and on each side of the two flanges inner faces.

Can you truss  the accuracy of your hernia gauge???

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1 hour ago, Goliath said:

Sometimes it can be leak free for ages, then something hits the prop and it takes a little while to settle again. 

Ahah!  That happened to me.  But what exactly has happened in this circumstance??

Edited by system 4-50
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4 minutes ago, system 4-50 said:

Ahah!  That happened to me.  But what exactly has happened in this circumstance??

The impact makes the prop shaft wobble and this compresses the packing in the gland  leaving a slightly larger gap and the water gets in.  After the prop has cleared the shaft wobble stops and the packing recovers its original shape (nearly).  At the same time the grease flows slowly in to start filling the bigger gap.  Together these effects stop or nearly stop the water entering.

N

5 minutes ago, ditchcrawler said:

I would expect the nuts to be at the very end of the threads after only a couple of months use. 

The outer end, not the inner end.  I think whoever fitted the OP's gland has not used enough packing, or the packing is too small.

N

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So your boat builder didn't even put primer over the bare steel?

If they didn't bother in the bits you can see, can we assume they certainly didn't bother in the bits you can't see?

I'd not be happy with this on a newly delivered boat!

 

As to the packing, whilst there appears to be "enough" to allow adjustment for years to come, I do agree with those who say it would be better with an extra ring added to it.  Better in my view to have the area contacting the rotating shaft as large as it can be, as there is always a tendency for the shaft to wear, and I think that tendency is reduced the greater the area you have in contact.

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1 hour ago, alan_fincher said:

So your boat builder didn't even put primer over the bare steel?

If they didn't bother in the bits you can see, can we assume they certainly didn't bother in the bits you can't see?

I'd not be happy with this on a newly delivered boat!

 

As to the packing, whilst there appears to be "enough" to allow adjustment for years to come, I do agree with those who say it would be better with an extra ring added to it.  Better in my view to have the area contacting the rotating shaft as large as it can be, as there is always a tendency for the shaft to wear, and I think that tendency is reduced the greater the area you have in contact.

I believe we did warn Rob about the workshop and sales place near lock 13 of the GU

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Thanks for all your replies, much appreciated. Re boat appreciate the feed back re engineering/dodgy work etc. As a way of explanation when looking around we came across all sorts of horrors and would not have got any boat if looking for everything...… so bit the bullet and are going on the basis we got the boat knowing the reputation of the broker and will look to improve over the years on the bits we find. We like the boat generally and its condition. These bits can be changed/updated over time plus it gives me more opportunities to learn new skills!

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1 hour ago, robtheplod said:

Thanks for all your replies, much appreciated. Re boat appreciate the feed back re engineering/dodgy work etc. As a way of explanation when looking around we came across all sorts of horrors and would not have got any boat if looking for everything...… so bit the bullet and are going on the basis we got the boat knowing the reputation of the broker and will look to improve over the years on the bits we find. We like the boat generally and its condition. These bits can be changed/updated over time plus it gives me more opportunities to learn new skills!

If you do repack it I would suggest PTF packing, mine has been in 20 years now

 

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21 minutes ago, ditchcrawler said:

If you do repack it I would suggest PTF packing, mine has been in 20 years now

 

Do you have an Aquadrive or similar or a rigidly mounted engine. If so I think that will have a lot to do with long packing life. Mine with an Aquadrive has probably lasted longer possibly about 29 years. I think it is because the shaft cant slide in and out as the engien mounts deform under prop thrust and the engine can't bang the shaft about in the gland.

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Just now, Tony Brooks said:

Do you have an Aquadrive or similar or a rigidly mounted engine. If so I think that will have a lot to do with long packing life. Mine with an Aquadrive has probably lasted longer possibly about 29 years. I think it is because the shaft cant slide in and out as the engien mounts deform under prop thrust and the engine can't bang the shaft about in the gland.

Spot on

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4 hours ago, alan_fincher said:

 

As to the packing, whilst there appears to be "enough" to allow adjustment for years to come, I do agree with those who say it would be better with an extra ring added to it.  Better in my view to have the area contacting the rotating shaft as large as it can be, as there is always a tendency for the shaft to wear, and I think that tendency is reduced the greater the area you have in contact.

I looked at a discarded prop shaft in a boat yard the other day, and it had a very smooth rounded groove worn into it by packing. I was surprised, the groove must have been 1/4” deep, and maybe 1/2” wide. 

 

 

 

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