overheating sterngland

[james]

Hi im new to this and this is my first post.  sorry for lots of detail ,  i hope someone could help me with this problem, i have a 27ft cruiser with a 1.8 bmc on shaft with conventional stuffing gland.  recently i have had an engineer replace the flexi hose because it was showing signs of breaking down. he repacked the gland,  checked for wear to gland, shaft and cutlass all ok.  we refloated the boat.  whilst running the engine in gear for 20mins i noticed the gland was very hot too touch and no matter how i slackened the packing gland i was not getting a drip at all. convinced it had been packed to tight , he came back repacked it checked  shaft alignment.  it was still getting hot so we rang a well known manufacturing company of these stuffing boxes  and he said if i could hold onto it comfortably for 5 seconds it was ok and explained about a hot cup of tea and how you proberbly wouldnt be able to hold that at all , he did however tell me to keep an eye on it.  I used the boat for 1.5hours today at about 1200 revs  adjusted so i was getting a steady drip (bit more than id like but im obviously trying keep it cool)  i stopped added some grease nearly stopped the drip, good i thought!.  When i check the temp it was even hotter!!, say two seconds and then i had to let go . there is no smell or  steam and i dont know if this was getting hot before because i never checked it.  Now my question is....... am i worrying  over nothing , does any one know what sort of temp it needs to reach before stainless steel  and bronze starts to suffer !!!   i am the sort of person that likes things just so and it just  dosent seem right !!!  any thoughts or suggestions would be greatly appreciated.  fantastic forum  by the way i have solved many problems and learnt so much just by reading other posts.  (Its the bronze type with two studs with nuts on them)

 

thanks in advance james 

[bizzard]

52 minutes ago, james said:

Hi im new to this and this is my first post.  sorry for lots of detail ,  i hope someone could help me with this problem, i have a 27ft cruiser with a 1.8 bmc on shaft with conventional stuffing gland.  recently i have had an engineer replace the flexi hose because it was showing signs of breaking down. he repacked the gland,  checked for wear to gland, shaft and cutlass all ok.  we refloated the boat.  whilst running the engine in gear for 20mins i noticed the gland was very hot too touch and no matter how i slackened the packing gland i was not getting a drip at all. convinced it had been packed to tight , he came back repacked it checked  shaft alignment.  it was still getting hot so we rang a well known manufacturing company of these stuffing boxes  and he said if i could hold onto it comfortably for 5 seconds it was ok and explained about a hot cup of tea and how you proberbly wouldnt be able to hold that at all , he did however tell me to keep an eye on it.  I used the boat for 1.5hours today at about 1200 revs  adjusted so i was getting a steady drip (bit more than id like but im obviously trying keep it cool)  i stopped added some grease nearly stopped the drip, good i thought!.  When i check the temp it was even hotter!!, say two seconds and then i had to let go . there is no smell or  steam and i dont know if this was getting hot before because i never checked it.  Now my question is....... am i worrying  over nothing , does any one know what sort of temp it needs to reach before stainless steel  and bronze starts to suffer !!!   i am the sort of person that likes things just so and it just  dosent seem right !!!  any thoughts or suggestions would be greatly appreciated.  fantastic forum  by the way i have solved many problems and learnt so much just by reading other posts.  (Its the bronze type with two studs with nuts on them)

 

thanks in advance james 

Try whilst stationary turning the prop shaft by hand with the gearbox in neutral. It should turn without too much strength. If it won't then maybe some strands of old packing have been forced down between the shaft and bearing. You say Cutless bearing. A cruiser ? which might mean the Cutless bearing is perhaps on a separate A or P bracket under the stern carrying the tail end of the shaft and prop,  if so is this correctly inline with the inboard gland.

[james]

Thanks for your reply, the shaft is easy to turn by hand.  Yes your right the it is underneath the boat , the engineer first checked the cutlass when on the hard a month ago.  so i wouldnt know about it being in line now its back in the water.

 

 

[rgreg]

I recently re-packed mine and, although the shaft could be turned easily by hand, it quickly got hotter than I was happy with. I removed one ring of packing and adjusted the pusher until I found the sweet spot of very little dripping and cool running.

[bizzard]

1 minute ago, james said:

Thanks for your reply, the shaft is easy to turn by hand.  Yes your right the it is underneath the boat , the engineer first checked the cutlass when on the hard a month ago.  so i wouldnt know about it being in line now its back in the water.

 

 

 Is the hose you mentioned that was replaced connecting the packing gland top bearing with the out going tube held on with Jubilee clips? If so the new bit of tubing might be stiffer than the old one and not aligning itself properly. You could try slackening off the clips at one end and running in gear for a bit to align, settle it and then retightening the clips.

[james]

ok that sounds interesting i will give it ago, if i slacken it ...will it leak quite a lot?  i would be afraid it could pop off then i would panic big time lol.

 

I might try removing one of rings if all else fails.  thanks for the info

 

 

[Bee]

Unlikely to suddenly let in a lot of water, I've actually withdrawn a shaft while in the water - lots of water but a rag stuffed in the hole stopped it till I replaced the shaft. Why did I withdraw the shaft? Can't remember, must have been important though.

[MtB]

29 minutes ago, james said:

ok that sounds interesting i will give it ago, if i slacken it ...will it leak quite a lot?  i would be afraid it could pop off then i would panic big time lol.

 

I might try removing one of rings if all else fails.  thanks for the info

 

 

 

Mitigate this risk by checking your bilge pump works before dismantling the stern gland. 

[james]

Hi , I tried adjusting the flexi hose as suggested but it hasn’t made a difference.  Does anyone know if damage only occurs when things get scolding hot , if so I’m gonna stop worrying about it because I think I might be chasing a red herring at the moment I can hold my hand on it and count to 2 and there is no smell or steam and there is 5 drips a min underway  I don’t feel. Confident removing a ring of packing although I’m glad it worked for you mate !

[Boater Sam]

There is not a lot of gap to the pusher for a gland that has just been repacked, the nuts are well screwed down.

[rgreg]

1 minute ago, Boater Sam said:

There is not a lot of gap to the pusher for a gland that has just been repacked, the nuts are well screwed down.

No, it looks very tight for a newly packed gland; on mine the locking nuts are almost at the end of the bolts.

[David Mack]

Perhaps there is too little packing in there, so the gland has to be tighter to seal over the shorter packed length.

[alan_fincher]

38 minutes ago, Boater Sam said:

There is not a lot of gap to the pusher for a gland that has just been repacked, the nuts are well screwed down.

 

34 minutes ago, rgreg said:

No, it looks very tight for a newly packed gland; on mine the locking nuts are almost at the end of the bolts.

 

Agree entirely.

 

I can't see there can be much packing in there.

 

And IMO they should never be anything like hot enough that you can't hold them continually with no risk of burns.

 

Something sounds very wrong to me.

[ditchcrawler]

On my screen the packer doesn't look parallel with the end of the tube, could be camera angle of course

 

[cereal tiller]

8 minutes ago, ditchcrawler said:

On my screen the packer doesn't look parallel with the end of the tube, could be camera angle of course

 

Yep ,left hand gap appears smaller .

[james]

The engineer packed it with 3 rings of    Packing and they are reputable engineering firm.  I checked the pusher and it’s not tight at all only just touching the packing to be honest.  The whole thing is a mystery ?

I measured gap exactly 17mm each side 

[cereal tiller]

18 minutes ago, james said:

The engineer packed it with 3 rings of    Packing and they are reputable engineering firm.  I checked the pusher and it’s not tight at all only just touching the packing to be honest.  The whole thing is a mystery ?

I measured gap exactly 17mm each side 

Was the Packing Lubricated with Light Oil (3 in one or similar) during Assembly?  

[system 4-50]

The pusher just doesn't look at 90 deg to the shaft.

[alan_fincher]

51 minutes ago, james said:

The engineer packed it with 3 rings of    Packing and they are reputable engineering firm.  I checked the pusher and it’s not tight at all only just touching the packing to be honest.  The whole thing is a mystery ?

I measured gap exactly 17mm each side 

 

Try measuring the distance between the end of each stud, and the nearest part of the shaft.

It ought to be near as damn it the same both sides.

It may be a trick of the photograph, but the far end of the left hand stud looks to be significantly further from the shaft than the far end of the right hand stud.

 

If it really is, then (assuming it is all correctly engineered), the shaft isn't straight through the gland.

 

It may be nothing to do with the overheating, but it doesn't look symmetrical, and should be.

[james]

No oil used , honestly it’s just the camera angle.  Phoned another leading sterngland manufacturer they  agreed if everything has been checked and there’s no smell or steam, it’s well greased and it’s drip rate is 3 or 4 times a min for it to be hot is not unusual ! .  The problems arise when it’s tight and people try to make it run dry or of corse it badly misaligned.  As far a temp goes (which was my original question) bronze can withstand a massive temp and be turning blue before my eyes so I have nothing to worry about .  That all being said relies on everything else being ok .  The shaft could be bent but even then wouldn’t I have other tell tale signs.  For now I think I will enjoy the boating season , and have it all apart when it’s on the hard ?

[MtB]

49 minutes ago, james said:

No oil used ,

 

There's the problem then, I suspect. The packing is running dry of lubrication.  Along with simply not enough packing in there. 

 

Good reputation or not, I think it has not been packed competently or properly by this firm. Try loosening it then pumping grease in through the greaser until it emerges around the packer, then tighten the packer again. This might make it run cool. 

 

And although the bronze can withstand high temperatures that bit of rubber pipe can't!

[Bee]

Well the only thing that can cause the heat is friction so there must be something tight, maybe carefully remove the pusher thingy then bung a load of oil in and put it back together, see how it goes, nothing bad ought to happen, I would try that just to avoid wearing the shaft - suprising how it can, my shaft is a second hand one running on unworn sections, its about 2m long, would have cost someone a lot of money to replace.

[Tony Brooks]

On all the stern glands of that design I have dealt with the grease cap is on the gland, not behind the rubber hose. The part of the stern gear where the OP's has the greaser had a hole much larger than the shaft so the shaft was supported by the aft Cutless bearing and inboard by the engine. The give in the rubber Cutless bearing and the rubber hose allows the engine to "shake" the shaft about while minimising vibrations.  Te greaser greased the packing assembly.

 

The greaser position on the OP's photo suggests it has a plain metal bearing below the greaser so unless the whole hose gets filled with grease no grease can get to the packing - even then I suspect the grease would exit the bearing to the back.

 

It looks to me as if the rubber hose may be slightly distorted that suggest the shaft may not be running true. This may be an optical illusion though, like the pusher.

[MtB]

10 minutes ago, Tony Brooks said:

The greaser position on the OP's photo suggests it has a plain metal bearing below the greaser so unless the whole hose gets filled with grease no grease can get to the packing - even then I suspect the grease would exit the bearing to the back.

 

 

Not being familiar with glass fibre hulls this stern gland arrangement looks to me like a right lash-up, from a pure engineering point of view. And yes the greaser cup position (and size) seems all wrong and I can't imagine how this would ever work, only connecting to the packing gland via a dodgy-looking bit of cooling hose.

 

Are they always like this on glass fibre hulls or is this one a 'one off' bodge up?

 

Did the gland ever work correctly? Why did it need re-packing in the first place?

[Tony Brooks]

I do not like these "flexible" stern glands but yes, all those on the hire fleet worked OK but as I described they were rather different to the OPs. Very common on any boat that has a Cutless outboard bearing and rubber engine mounts because the ones I ma familiar with allowed the engine to dance about without transmitting so many vibrations to the hull.

 

The designs varied a little but in all case (apart from one where a clown ad taken a hacksaw to it) the back of the gland and the front of the bit were the OP has a greaser had a par of dogs cast in. These should be all but fully engaged so if the gland gets a bit tight any torsion on the gland case is transmitted via the dogs ad to the rubber hose.  The OP's hose looks a bit long to me so if his setup has the dogs they may not be properly engaged but  i have not ad that  gland apart so don't really know..