stern tube seals..... if it aint broke...

[smeaks]

How old is too old for a stern tube seal? If it is not leaking what other signs should I look for? My seal has an oil dash pot and so will proably be mechanical rather than using packing - I am unsure of manufacturer or type. My concern is that with such an item sudden failure could be catastrophic, but I have no idea on how to asess condition without removal and strip down which might as well be a replacement. So how often should it be replaced, if they do fail is the consequence sudden flooding or less dramatic, what emergancy procedure/fixes are applicable or recomended in such a situation.

I look forward to the advice.

 

[Channel Ribs]

Crickey, a good question indeed.

From my own recent experience, you do not want a catastrophic failure - thats for sure. /forums/images/graemlins/frown.gif

While I was replacing the shaft in my own boat I noticed that the rubber hose between gland and tube had a split, if I had not taken the thing apart to make getting the new shaft in easier I would have never known. I have put it back in place and am now looking for a replacement, but knowing it is there certainly weighs heavy.

That given, my advice would be to strip down and inspect everything if only to put it all back the same. If there are any cheap components which you can measure up before hand then it would be silly not to get them to swap out, but as for an entire overhaul.... I will leave that for better minds than I to judge. /forums/images/graemlins/smile.gif

 

[cliff]

[ QUOTE ]
How old is too old for a stern tube seal? If it is not leaking what other signs should I look for? My seal has an oil dash pot and so will proably be mechanical rather than using packing - I am unsure of manufacturer or type.

[/ QUOTE ]O.K. - not sure what type of seal you have - a photo posted on here might help. If it is similar to the seal on RB which has an oil reservoir the actual sealing is achieved by rubber lip seals which are easily obtained from the likes of Fenners - just make sure you order "Niton" seals - these have stainless steel springs. There are three seals in the setup I have, front seal (nearest the g'box) the spring faces rearwards. In the aft end of the unit the inner seal has the spring side facing forwards and finally the rear outer seal is fitted with the spring side facing aft. The oil if fed between the front and middle seals and lubricates the bearing between the shaft and the unit.

The seals are easy to change and from experience can last more than 5 years depending on motoring hours etc. The type described does not fail suddenly, rather it will develop a leak and allow the oil to leak out - watch the level of oil in the reservoir - should not use more than a couple table spoonfuls a season.
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