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Old 24-06-2014, 23:23   #1
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Leaking Prop Shaft

I ran the engine today and after I noticed a dripping sound. Tracked it down to the prop shaft. Its a v drive and the dripping is coming from a connection just below where the shaft emerges from the transmission.

Can anyone give me an idea about what might be causing the leal and what I should do to fix it?

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Old 24-06-2014, 23:43   #2
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Re: Leaking Prop Shaft

That's what is known as the shaft coupling.

There is a seal in there that needs servicing or replacing.

Looks like a crappy place to work for access.

If you don't know what it is you need a boatyard and boat mechanic.
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Old 24-06-2014, 23:51   #3
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Re: Leaking Prop Shaft

I'm going to have to haul the boat to fix it?

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Old 25-06-2014, 00:46   #4
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Re: Leaking Prop Shaft

At least on the Cal 34 Mark 1 I know it can be worked on without disassembling any engine/tranny parts. No you don't have to haul the boat. It's hard to get to, I think the owner of the Cal 34 I sailed on made a tool to access the nut IIRC.

The stuffing box might only need to be tightened. How tight:
Soo, how tight should the stuffing box be.?

How to replace stuffing box packing:
Re-Packing A Traditional Stuffing Box Photo Gallery by Compass Marine How To at pbase.com
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Old 25-06-2014, 08:05   #5
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Re: Leaking Prop Shaft

If it only needs adjusting and can be accessed it can be done in the water.

If it needs replacing you will need to haul out.

Based on how difficult it looks to access I am guess it hasn't been adjusted in a while.
To understand a bit - The prop shaft spins, it goes through a tube to get outside the boat.

To seal the tube there is a seal that "rubs" against the shaft and so it wears. Rubbing also creates heat. There are a few types of seals. They are also called stuffing boxes because ancient ones were like a box "stuffed" with material. The heat needs to be cooled as well so some are designed to weep water for cooling.

There are modern fancy ones that don't need servicing that have cooling circuits and such. "Recent" ones use a material but are adjustable so as they wear they can be tightened a few times until they need to be replaced.
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Old 01-07-2014, 13:21   #6
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Re: Leaking Prop Shaft

Looks like just an older-style packing gland leak, it is in a lovely spot to access. Two wrenches are required, loosen the locking nut(the thin one closest to the hull fitting)a turn or more clock-wise,while holding the packing nut (the wider "nut") from turning. Then tighten the packing nut ,also clock-wise, a quarter turn at a time until the drip stops dripping. Hold it stationary and bring the lock-nut back up to it snuggly. Now run your shaft slowly and carefully observe the gland, you should get one drip every five to ten seconds while the shaft is rotating, just enough to keep your packing material lubricated and cooled. If you find the packing nut will not tighten any more or doesn't stop the leak,or you have no more threads to back off the locknut,you probably need to re-pack the gland(a job requiring hauling), pick all the old packing out of the inside of that packing nut,(may require a special tool), you may have the traditional waxed jute packing or the newer woven teflon material but both have to be the right thickness to fit inside the nut, cut into rings(usually three or four) that just fit round the shaft. You alternate the cut ends 180 degrees as you push them into the nut. Tighten the nut back onto the hull fitting snuggly, then back it off once you are back in the water, until you get a fast drip.then retighten it as explained above. Most packing glands will run for years with nothing more than the very occassional tightening, if you find you have to tighten it often then you have alignment problems or wear on some other component, ie: v-drive bearings, shaft cutlass bearing(outside the hull)worn out, or a worn shaft in the area of the packing gland from over-tightening the gland or abrasive(sand) having been pulled into the shaft fittings.
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