What to do about stern bearing unit (stuffing box)

S

sjfcanada

.
Jun 11, 2012
9
I had some reply from my other post that were good, but I read somewhere that some people always had problems with their stern bearing unit (stuffing box) on their combi set up with variable prop and Volvo md6a.

I pulled the Vega from the water for a few reasons, one being the stern bearing unit (stuffing box) the forward seal ring 840252 leaks bad every time I run the motor, have to grease the stern bearing unit after every run, or I better have a good bilge pump with unlimited electric.

Motor seems good still, and I just want not to worry about getting my batteries flooded or worst case Sink, so what would you do or have done other than replacing the motor set up!

Should I take out the shaft and just install new stern bearing bushing and seal rings and then repack with special grease and this will most likely fix having to grease after every motor run,

Should I install New prop and new shaft and new transmission, and modern stuffing box, if I can do this what type of set up do you know about, and do you know some dealer with experience with this who could sell me the parts?

Or is there a modern stuffing box that will work with my set up, if so what type size make model?

Lost on what to do.

Stephan
 
J

johnadenney

.
Oct 30, 2011
221
Hi Stefan, you have my sympathy! I am no expert on the Combi system but I have taken mine apart and totally refurbished it - all new seals and bearings.

Firstly - I did not enjoy the task!

I have a very simple arrangement at the stern - the prop shaft and the combi control tube exit the boat via a (bronze?) bearing housing (is this the suffing box?)which is attached to short piece of rubber tube which is attached to the tube which is glassed into the back of the yacht. The bearing housing (stuffing box?) has a couple of plain white metal bearings inside it to support the control tube for the prop blades and a couple of rubber seals at either end to keep the oil in (I guess?). The whole thing has a gravity feed oil supply - just a tube from a plastic container of oil to a nipple on top of the housing. When the engine is running this gets quite warm on mine! The arrangement of the rubber seals at either end was confusing - I cannot remember which way they faced but I remember thinking it was strange!

The rubber tube at the back I guess gets full of sea water? I presume the jubilee clips keep the water out of the boat? Does yours leak here?

I had a new stern bearing made from bronze and fitted with a nylon bearing with holes drilled in it to allow water in for cooling. It sat in a big rubber bush to give it some flexibility. I assume that water will find its way into the rubber tube at the rear via the "cooling water" holes and inevitable gaps? Before I did this job the prop could be moved up and down a few mil - now it is secure with very little play.

So - I guess the prop shaft will have to be removed to fix the stern bearing / stuffing box and I guess while it is out it would be wise to sort out the combi unit as well?

The combi unit is a clever bit of engineering and I managed to replace all the bits that can be replaced and it seems to run fine now. I had a major oil leak from the rear oil seal on the combi unit but it is fine also.... a bit strange because the combi is full of grease! I think the large oil seal at the rear of the engine was leaking as well - needless to say I replaced that.

If you take it apart take a photo of the way the clamp rings are fitted... easy to get them wrong! In fact take lots of photos!

I think I made every mistake possible when doing mine so I would not like to have to do it again - but having said that I quite like the way it works! How long it will stay oil and water tight is another matter! Maybe others with more experience can advise you but my view is that if it has worked ok for 30 years it must be a reasonable design and just fix it and keep it! (assuming engine runs ok!)

Good luck with it

John
 
J

johnadenney

.
Oct 30, 2011
221
Oh and just a note - there are TWO clamp rings at the front - so I had to take it all apart again.... if you know a mechanic who will do it for a fixed price - bite his arm off!
 
S

sjfcanada

.
Jun 11, 2012
9
Hi John,

No water does not leak at the rubber tube with the jubilee clips (C clamps) holding it to the back tube which is glassed into the back of the yacht and to the bearing housing (stuffing box).

My water leak is from where the forward seal, the one rubber seal that is exposed and where the grease is put into the bearing housing) at the bearing housing (stuffing box) that rubber seal also comes out when I put grease in bearing housing with grease gun if I put too much pressure, hope that let's you know what I am talking about.

Did you use any special grease like a water pump grease?

Does your bearing housing (stuffing box) rubber seal leak any more?

Thanks for the tips,
 
J

johnadenney

.
Oct 30, 2011
221
Hi, Now I see the problem! I guess the only proper solution is to fit
new seals and bearings - yuk! This means removing the prop shaft so I
would be tempted to change all of the seals and bearings (combi etc)
while you can. I would recommend buying extra seals and fitting them
over the control tube so that if they go again you can cut off the old
one and press in the new "spare" which is already over the shaft.... I
meant to do that myself but in the turmoil of the task I forgot...
....also I found that the shaft on mine was quite badly worn and
needed to be replaced. Fitting new seals onto a worn shaft may be a
bad idea. I believe Steve Birch has all the bits you may need.

I used marine grease in the combi - very sticky stuff! - but my
"stuffing box" thing is lubricated by gravity with thick oil -
(chainsaw oil)

All seals are now working as they should but bear in mind I replaced
just about every part that is likely to wear...

Good luck with it... it is a horrible job and hard on the back!

John
 
V

Vega1447

.
Oct 19, 2019
921
Albin Vega 27 Limerick
Hi John,
fitting extra lip seals over the control tube is an ingenious idea - I
wish I'd thought of it.

(I had my stuffing box etc rebuilt over the winter.)

Do the experts (Steve B?) have any comment on this idea?

John V1447 Breakaway
 
M

mnhdl

.
Oct 31, 2019
83
Hi! I'm not an expert...but I've done it and already used the second seal, it was very efficient and above all, it was sooooooooooo nice to be able to replace the seal without having to take the whole thing apart! Marie V3199 Elvire
To: AlbinVega@yahoogroups.com
From: John.Kinsella@...
Date: Mon, 18 Jun 2012 16:03:32 +0100
Subject: Re: [AlbinVega] Re: What to do about stern bearing unit (stuffing box)





Hi John,

fitting extra lip seals over the control tube is an ingenious idea - I

wish I'd thought of it.
(I had my stuffing box etc rebuilt over the winter.)
Do the experts (Steve B?) have any comment on this idea?
John V1447 Breakaway
 
V

Vega1447

.
Oct 19, 2019
921
Albin Vega 27 Limerick
Hi Marie/John.
Maybe a stupid question but I suppose that the "spare" lip seals are
inside the stuffing box (the bronze housing)?

Thanks

John V1447 Breakaway
 
M

mnhdl

.
Oct 31, 2019
83
no, mine was just there free on the tube, just in front the one in the housing
To: AlbinVega@yahoogroups.com
From: John.Kinsella@...
Date: Mon, 18 Jun 2012 16:14:51 +0100
Subject: Re: [AlbinVega] Re: What to do about stern bearing unit (stuffing box)





Hi Marie/John.

Maybe a stupid question but I suppose that the "spare" lip seals are

inside the stuffing box (the bronze housing)?
Thanks
John V1447 Breakaway
 
J

johnadenney

.
Oct 30, 2011
221
Just tape it up to stop it moving about and wearing away. I should
have put one at either end - the combi box seal as well... hindsight
is a wonderful thing! Anyway I hope the new seals last for a while if
not I shall try some sealant held in place by self amalgamating tape
to stem the flow of oil!
 
S

stevebirch2002

.
Nov 8, 2001
1,818
Hi John

I always add an extra seal to the kit so this can be done. Much easier to cut the worn one away and just push the new one in! Will have to add that to the instuctions but it does mention it in the Technical Notes.

Cheers

Steve BFrom: John Kinsella
Sent: Monday, June 18, 2012 4:03 PM
To: AlbinVega@yahoogroups.com
Subject: Re: [AlbinVega] Re: What to do about stern bearing unit (stuffing box)
Hi John,
fitting extra lip seals over the control tube is an ingenious idea - I
wish I'd thought of it.

(I had my stuffing box etc rebuilt over the winter.)

Do the experts (Steve B?) have any comment on this idea?

John V1447 Breakaway
 
V

Vega1447

.
Oct 19, 2019
921
Albin Vega 27 Limerick
Thanks Steve.
I shall speak unkindly to the mechanic that rebuilt the stuffing box.

He must have kept the spare lip seal as a souvenir.... He sure didn't leave it on the control tube.

Hey ho.

John V1447 Breakaway

John Kinsella
Mathematics and Statistics Dept
University of Limerick

Phone 0035361202148
Web jkcray.maths.ul.ie
 
You must log in or register to reply here.

Top Bottom