stern tube tightness

[micky1010]

Hello all,

 

I had my driveplate replaced a few months ago and the engineer loosened the stern tube in order to slide the propshaft back to remove the gearbox and then forgot to tighten it again afterwards.

I have tightened it myself upto when I met slight resistance, ever since I have a grease emulsion leaking from the front of the stern tube around the propshaft where it now drops into the bilge and gets splattered around the bay as the propshaft spins.

 

Does this mean I have over tightened it or not done it tight enough?

[RLWP]

Not tight enough, have another go

 

Richard

[micky1010]

Great thanks, I'll tighten it some more. Should it be tight tight or just tight?

[Phil.]

My understanding is that it should tightened enough that you can just turn the shaft manually.

Edited July 7, 2016 by Phil.

[RLWP]

My understanding is that it should tightened enough that you can just turn the shaft manually.

 

That's what I go for. Not tight tight, tight enough. We are talking the shaft here, not the nut(s) on the gland

 

Richar

[Horace42]

Assuming the packing cord - 'string' - was not removed during the operation - water is likely pour in if it was - then as already said - just tighten the gland nuts gradually.

Mine always leaked slightly. So I cut up a plastic bucked to make a circular guard to go around the shaft and seal.to catch the grease. I later fitted a 'deep sea' seal - no leaks at all - but left the guard in place.

[micky1010]

Yes it is the nuts on the front of the stern tube where the propshaft from the gearbox goes in . I will tighten it up and see if this stops the grease leak thanks.

[Iain_S]

Might have to do it a couple of times. If the gland has been slackened off, I tighten until I can JUST feel resistance when turning the prop shaft by hand, then do it again a couple of days later. Usually, that's all that's needed for a good few months after that.

[OldGoat]

If it's dripping grease and water, then you're using the wrong type of grease.

Calcium stearate grease is what's needed - as in K99 made by Morriss

[ditchcrawler]

Make sure you tighten the nuts evenly so the packer is straight, a little on each at a time.

[Greylady2]

As been said, we did ours it was free wheeling and dripping every second.

 

Half a turn each side and notch up the locking nut until it just about has some resistance.

[Sea Dog]

Hello all,

 

I had my driveplate replaced a few months ago and the engineer loosened the stern tube in order to slide the propshaft back to remove the gearbox and then forgot to tighten it again afterwards.

 

To add to the excellent advice above, I'd advise you not to use said "engineer" (grr!) to do any gas work.

[FadeToScarlet]

If it's dripping grease and water, then you're using the wrong type of grease.

Calcium stearate grease is what's needed - as in K99 made by Morriss

^^^this. Not all grease is waterproof, even the cheaper kinds of "marine waterproof grease".

[OldGoat]

FadeToScarlet, on 08 Jul 2016 - 11:31 AM, said:

^^^this. Not all grease is waterproof, even the cheaper kinds of "marine waterproof grease".

(from me:- If it's dripping grease and water, then you're using the wrong type of grease.

Calcium stearate grease is what's needed - as in K99 made by Morris)

 

I should have expanded the OP's entry that he had 'a grease emulsion dripping...' from which I infer he was using "any old grease" rather than a waterproof variety. To my mind the grease not only lubricates the inboard bearing but also blocks the passage of water to some extent. In his case the grease mixes with the water and washes the grease away - increasing the amount of fluid that finds its way into the bilge.

That's why the use of a lyophobic / calcium based grease is sensible (rather than the mantra of 'that's what we've always used' ). It doesn't have to be Morris's brand, even though at £3 odd it's not expensive. I have a large tin of Castrol grease that is of the correct specification and that works as well. IIRC it was sold as waterproof wheel bearing grease that I use in my dinghy trailer bearings. A decent motor factor should stock it....