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[TugCowboy]

After my first run with the new boat I got all this gunk coming out of the Port propshaft, just on the last run of 10 mins after the prop got fouled. Is it a case of too little oil in the shaft, perhaps too much play in it, or something else?


All help appreciated.

Alex

[BarryM]

Alex,

Fouled Prop > overheated shaft > lubricant viscosity drops > thinned and expanding lubricant expelled from shaft tube = "gunk" thrown out into boat innards?

Barry M

[Colin Bishop]

If you have oiled or greased the tube, as you should, then it's normal for some of it to find its way out of the top end as your photo shows. It may be being partially displaced by water getting in that the outboard end.

If you can, draw the shaft and relubricate it.

Colin

[DickyD]

Perfectly normal, most of mine do that.

[Colin Bishop]

Just as a further point, the threads on the ends of the shaft can act as miniature pumps depending upon which direction the shaft is rotating.

Colin

[andyn]

Mine do that too

[malcolmfrary]

When it STOPS doing that, re-lube as soon as possible.  Fitting a cover can help stop the stuff going everywhere.  I find that a couple of brass washers with a neoprene "o" ring between them at the prop end to act as a thrust washer/seal helps along with adjusting the collar at the inner end for minimum play.

[CGAux26]

Lubricant plus brass shaft log and SS shaft equals black wear particles.  As others have said some will make its way out the forward end and scatter around the boat.  Mine does.  But as to the threads acting as pumps, there should be no threads in the tube, particularly not in the bearing areas.  Threads will shred the soft brass bearing in no time.

[Circlip]

LH thread at the coupling end will keep it in the tube.

  Regards  Ian.

[derekwarner]

Well technically yes ........ a LH thread would remigrate the lubricant back into the tube.....BUT however we have discussed that 'generally' ...thread forms should not rotate in bearing elements

Another issue we would encounter is the diametrical clearance between stern tube bush ID & the rotating element OD is sufficient event at 1Bar....[atmospheric pressure] & the relative height differential between to two components to create the pressurised ingress of the lubricant 'up hilll'   & back into the hull...simple really.........Derek

[Circlip]

But you need to reverse that,-- wer'e in the Northern hemisphere 

  Regards  Ian.

[CGAux26]

But my boats have left hand props!!  And if the shaft threads are outside the bearing area, as they should be, this will have no effect. 

[MichaelK]

Mine does that as well, even without fouling the props.
Get a piece of kitchen paper towel and fold it into a flat strip, cut to the correct length, wrap it around the prop shaft where all the gunk is comming from, secure with tape or a clothes peg or something, and all the gunk stays in one place.
I regrease my shafts after every sail, it's no biggie.
Mick