Crevice corrosion and shaft seals ( again)

[pcatterall]

[FONT=Times New Roman, serif]Hopefully my 2 pics will appear. These relate to my previous thread about my dripping shaft seal.[/FONT]

[FONT=Times New Roman, serif]Special thanks to vyv for his valued comments on this and for his great site.[/FONT]
[FONT=Times New Roman, serif]One pic shows the general arrangement of my Tides Marine seal and the other where the seal had been in ‘static contact’ with the shaft while overwintering afloat.[/FONT]
[FONT=Times New Roman, serif]I think it is a good example of ‘crevice corrosion’ ( though I suppose we could call it ‘contact corrosion’ ?) [/FONT]
[FONT=Times New Roman, serif]You can probably also see two patches of 'corrosion’ on the shaft but the cause of that is uncertain as the shaft was new and there were no 'splattering s’ of paint or other stuff on it.[/FONT]
[FONT=Times New Roman, serif]I guess that if I had used the engine with the seal running in the rough corrosion of the groove then the seal would not have lasted very long?[/FONT]
[FONT=Times New Roman, serif]As indicated in the early thread I was able to 'reposition’ the seal along the shaft and it is working fine however I need to find a solution otherwise I will be buying a new shaft every year or so!![/FONT]
[FONT=Times New Roman, serif]Is it the case that any lip seal unit like mine which is laid up in ‘Mediterranean’ water for the winter will be susceptible to this kind of corrosion?[/FONT]
[FONT=Times New Roman, serif]How frequently will the engine have to be run to keep the water oxygenated?[/FONT]
[FONT=Times New Roman, serif]Would another kind of seal be better ( like a PSS type) ?[/FONT]
[FONT=Times New Roman, serif]I note that the TM1 seal is only guaranteed for one year. Unlike the TM sureseal the whole unit has to replaced meaning lift out 'splitting the shaft’ and fitting another (£150) unit....potentially every year... sounds ridiculous to me. To be fair this seal has lasted 3 years to date but it is a worry that it only has the 12 month guarantee.[/FONT]
[FONT=Times New Roman, serif]I am going to get a replacement unit to have on board, should I just get another TM1, get a TM ‘sureseal’ with a spare seal to have ready on the shaft or get something completely different[/FONT]

 

[pvb]

Can you fit a simple Volvo rubber seal or, better still, a Radice seal?

 

[pcatterall]

Can you fit a simple Volvo rubber seal or, better still, a Radice seal?

Yes (I guess) if they have the size for my shaft and housing. I hear good reports on the Volvo ....price, longevity, simplicity but with a lip seal on the shaft surely the same corrosion issues? Don't know anything about the Radice seal

 

[smithy]

Its not what you are asking but as for shaft repair you can get very thin sleeves to cover shaft damage, Google" speedie sleeves" I had to use one on my gearbox shaft when it suffered similar corrrosion. Much cheaper than a new shaft!

 

[pcatterall]

Its not what you are asking but as for shaft repair you can get very thin sleeves to cover shaft damage, Google" speedie sleeves" I had to use one on my gearbox shaft when it suffered similar corrrosion. Much cheaper than a new shaft!

Those sleeves look very useful but a bit narrow for a rubber lip seal where the shaft could move for and aft a bit? also it would increase shaft diameter beyond the seals tolerance? but not to the next size up.

 

[smithy]

I know what you mean about the shaft movement, I dont know if you can get longer versions. This is the standard repair for lip seal shaft damage, the sleeve is only a few thou thick and makes no difference to the seal.

 

[Tranona]

Yes (I guess) if they have the size for my shaft and housing. I hear good reports on the Volvo ....price, longevity, simplicity but with a lip seal on the shaft surely the same corrosion issues? Don't know anything about the Radice seal

The Radice seal is essentially the same as the Volvo seal except that it has a vent so that it does not need burping to expel air when you launch and the seals can be greased through a little nozzle rather than the fiddly way of getting grease between the seal and the shaft. Keeping the seals greased may reduce the chances of crevice corrosion when the boat is unused. Sillette are the distributor of Radice and the details of sizes available are on their site. Less than half the price of a Tides, so you can afford to treat yourself to a couple of beers when you have done the job!

 

[MoodySabre]

I had wear on the shaft where the TM lip seal was. No corrosion. There's plenty of silt in the water round here so I have opted for a PSS and no further wear on the shaft.

 

[HenryEDM]

I'd suggest a pss seal since it is the face seal type rather than lip seal

 

[pcatterall]

Thanks guys, plenty to think about there. I had thought about PSS as then any crevice type corrosion would occur on a renewable component??

 

[vyv_cox]

Thanks guys, plenty to think about there. I had thought about PSS as then any crevice type corrosion would occur on a renewable component??

I found pitting on the stainless steel rotating face a few years ago at launch time. I assumed that this might be crevice corrosion due mainly to seawater, so since then I always flush with fresh water before leaving the boat, which has kept the other side of the seal (reversed) free of pitting ever since. I have heard from one other user who had the same problem but no others.