Help my TM seal is leaking

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pcatterall

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Just back on board in Sardinia where the boat has wintered afloat. No water in bilges but after running engine there was adrip from the seal. On investigation pushing back the seal there is a groove around the prop and forward of that a sort of pit in the new as shaft about half a mm deep. Very concerning to me going ahead there is. Slight drip going astern much faster. When stopped I can push the seal back and on release the dripstops.
Is safe to use the boat or could the whole seal go and loads of water rush in?
While afloat would it be possible to shorten the flexible hose so that the seal is on a better part of the sha ft?
Is the groove due to deposits on the seal wearing the shaft?
Seal has only done 200 hours.

I have photos which I will try to send later
Any advice please?
 
We had similar trouble with a Tides seal making a groove in the shaft .We moved the bellows along the stern tube and re positioned the seal, which stopped the leak for a while .The advice was to run the engine more frequently ,2 week intervals over the winter months .
Running in gear later in the season ,we discovered the 2 blade Max prop was worn in the gearing causing shaft occilation,at various revs .Changed the prop and the seal to a conventional one cured it .:)
 
Your description sounds like crevice corrosion. I have not come across it on a seal but there are photos on my website of examples of it under cutless bearings and under blobs of either antifouling or marine growth. It's a consequence of using stainless steel for shafts, although some manufacturers are saving costs by specifying inappropriate grades for this duty. Moving the seal along the shaft will overcome the problem temporarily but no doubt it will return.
 
Thanks guys.
Managed to shorten the articulated hose by 5mm which moved the seal from the groove and cured the leak.
Two questions arise.
Can I order the other (tm2?) Seal as an alternative then at least I can have a spare seal ready on the shaft.
I will investigate what is causing the corrosion ,presumably an annode issue, can I use a cable with an annode thrown overboard and direct to the shaft when we leave the boat for any time?
Thanks again.
 
pcatterall said:
Thanks guys.
Managed to shorten the articulated hose by 5mm which moved the seal from the groove and cured the leak.
Two questions arise.
Can I order the other (tm2?) Seal as an alternative then at least I can have a spare seal ready on the shaft.
I will investigate what is causing the corrosion ,presumably an annode issue, can I use a cable with an annode thrown overboard and direct to the shaft when we leave the boat for any time?
Thanks again.
Click to expand...

If it is indeed crevice corrosion as Vyv suggested then an anode will not do anything. Description of crevice corrosion and its causes on Vyv's site or google the term.
 
Tranona said:
If it is indeed crevice corrosion as Vyv suggested then an anode will not do anything. Description of crevice corrosion and its causes on Vyv's site or google the term.
Click to expand...
Thanks I will goggle and get more info. With thousands of as shafts and potentially similar problems why do I not see more mention of it and is there any solution?
 
pcatterall said:
Thanks I will goggle and get more info. With thousands of as shafts and potentially similar problems why do I not see more mention of it and is there any solution?
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I suspect it is a combination of a number of factors. Firstly, it probably needs several stationary months immersed in seawater for the problem to occur. Secondly, it is doubtful whether many people would recognise it for what it is. Thirdly, a very specific geometry is needed in seals and bearings for it to be a problem. The page on my website is here http://coxengineering.sharepoint.com/Pages/Crevice.aspx
 
vyv_cox said:
I suspect it is a combination of a number of factors. Firstly, it probably needs several stationary months immersed in seawater for the problem to occur. Secondly, it is doubtful whether many people would recognise it for what it is. Thirdly, a very specific geometry is needed in seals and bearings for it to be a problem. The page on my website is here http://coxengineering.sharepoint.com/Pages/Crevice.aspx
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Thanks vyv you site was very interesting. I will check my shaft with a magnet !! I guess also that the engine should be run in gear a bit to get some oxygenated water flowing . This also a gods reason to lift out over winter but ensure the seal is drained.
Thanks all again.
 
I think I remember reading somewhere that the tides marine seal can fail catastrophically and is no longer marketed by some suppliers. Maybe consider changing for a PSS as lifeboats are rare in Sardinia.
 
ghostlymoron said:
I think I remember reading somewhere that the tides marine seal can fail catastrophically and is no longer marketed by some suppliers. Maybe consider changing for a PSS as lifeboats are rare in Sardinia.
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Think you might have that the wrong way round. Seals that rely on double seals running on the shaft fail progressively - that is one of their characteristics, just like the Volvo seal.
 
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