Alanpat
regular
Reged: 10/08/2007
Posts: 73
Loc: River Crouch, Essex
|
|
I have replaced my 3 bladed fixed prop with a 2 Bladed Bruntons Varifold Folding Prop. And my old grease filled stuffing box stern gland with a PSS Shaft Seal..
When the engine is in neutral (I guess because the PSS Shaft Seal is not as rigid as the old grease filled stuffing box) the prop shaft sounds like a bucket full if spanners as the prop shaft knocks on to the inside of the stern tube .. It stops at around 1000 revs the gets increasingly worse as you open the throttle.
I dont know if the problem lies with the Shaft Seal or the Prop, or a combination of the two.
We have a new cutlass bearing and checked the engine alignment and all the other obvious causes.
Has anyone else experiences similar problems.
Look forward to your comments 
|
sailorman
regular
Reged: 21/05/2003
Posts: 11464
Loc: East Coast
|
|
@ a guess you have a Yanmar 1GM 
--------------------
http://photobox.tiscali.co.uk/album/1040810g
If your dog is barking at the back door and your wife is yelling at the front door, who do you let in first?
> The dog, of course. He'll shut up once you let him in.
My Son Has a "Cinder 22" for Sale new Yanmar 1GM fitted with about 10 hrs use
|
Alanpat
regular
Reged: 10/08/2007
Posts: 73
Loc: River Crouch, Essex
|
|
No.. VP 2002 18 HP
|
sailorman
regular
Reged: 21/05/2003
Posts: 11464
Loc: East Coast
|
|
--------------------
http://photobox.tiscali.co.uk/album/1040810g
If your dog is barking at the back door and your wife is yelling at the front door, who do you let in first?
> The dog, of course. He'll shut up once you let him in.
My Son Has a "Cinder 22" for Sale new Yanmar 1GM fitted with about 10 hrs use
|
webcraft
regular
Reged: 08/07/2001
Posts: 4402
Loc: al shop for local people
|
|
Quote:
We have a new cutlass bearing and checked the engine alignment
How did you check the engine alignment? Are you sure the shaft is central in the stern tube? There is no way there should be enough movement to cause the shaft to hit the stern tube provided:
~ the shaft is central in the stern tube
~ the engine alignment is good
~ the engine mountings are good
It is not the job of the stuffing box or stern seal to align the shaft in the tube - there should not be any lateral force on it. With a PSS seal or Volvo type you risl leakage and damage if the shaft is not central in the stern tube when spinning.
- W
--------------------
Comprehensive UK sail cruising website
BlueMoment - blown away into the blue . . .
|
Tranona
regular
Reged: 10/11/2007
Posts: 1519
|
|
The problem with this type of seal is that it does not provide any support radially for the inboard end of the shaft unlike your original stuffing box. Shaft movement to the extent that the shaft knocks against the tube is not uncommon. You do not say what your stern tube design is - did it have a bearing as well as the stuffing box? Also whether you have a flexible coupling on the gearbox end which reduces some of the engine movement to the shaft.
As many posts on this forum suggest, the Volvo seal is the preferred replacement for a conventional stuffing box because it is drip free, provides bearing support for the inboard end of the shaft and is less than half the price of other designs. In some installations, for example with a Stuart Turner type stern tube a short piece of cutless bearing on the inboard end ensures the shaft is located centrally in the tube. Engine movement can then be isolated from the shaft by the use of a flexible coupling such as R&D or more sophisticated designs such as Bullflex or Centrica.
Hope this helps
|
Tranona
regular
Reged: 10/11/2007
Posts: 1519
|
|
Sorry, should have said Centraflex - too much time looking at share prices!
|
oilyrag
regular
Reged: 03/07/2002
Posts: 300
Loc: E Coast UK
|
|
Had exactly this same problem and evetually solved it (mostly) by swapping to a larger diameter stern tube - original 1" shaft and 1.25" ID stern tube, changed to 1.5" ID stern tube. There was not sufficient clearance to fit an inboard cutless to the original tube but that was my preferred solution.
As others have said the important thing is to ensure that the shaft is aligned centrally in the stern tube - it isn't doing any harm by knocking if everything is aligned properly.
|
john_morris_uk
regular
Reged: 03/07/2002
Posts: 3717
Loc: Plymouth UK
|
|
Quote:
As many posts on this forum suggest, the Volvo seal is the preferred replacement for a conventional stuffing box because it is drip free, provides bearing support for the inboard end of the shaft and is less than half the price of other designs.
I don't think that 'Volvo seal is the preferred replacement for a conventional stuffing box' can be sustained.
Lots of people (including ourselves) have fitted the PSS seal and it's excellent. The Volvo seal isn't designed to give support to the shaft as far as I can remember. When we bought our boat, I had to remove the Volvo seal, because it had worn into an oval and leaked like a tap.
On our previous boat we had a problem with the shaft hitting the inside of the stern tube, but that was an alignement problem and not caused by fitting the PSS shaft seal.
We have only paid in the region of £100 for our PSS seals. Are Volvo shaft seals really £50?
--------------------
“When you discover that you are riding a dead horse,
the best strategy is to dismount.”
|
Alanpat
regular
Reged: 10/08/2007
Posts: 73
Loc: River Crouch, Essex
|
|
________________________________
Quote
I had to remove the Volvo seal, because it had worn into an oval and leaked like a tap.
______________________________________
Was this caused by a 2 bladed prop being out of balance ?
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
