Stuffing box questions

[AZ-Oldguy]

Hi oh Great Source of collective wisdom, I need to change out the engine mounts on my Yanmar, 3QM30, in my Endurance 35 Cutter.

There is a flexible coupling plate that joins the Stainless shaft to the back of the transmission, with four large studs fore and aft, that I will need to remove in order to disconnect the engine from the shaft so I can lift up the engine a bit.

I am assuming that the next step will be to slide (pound/drive ) the shaft back a bit so that I can free the engine from the shaft.

The Stuffing box looks old and green, but seems to be working well. The manual for the engine (1980 model) observes that the stuffing box has lignum vitae in it. It is connected to the stern tube with a short length of heavy hose and hose clamps. A small water line from the heat exchanger and water pump">raw water pump connects to this short length of heavy hose.

My question is, should I loosen the nut (a lot or a little)
before I try to slide the shaft aft? Will it leak a lot or a little? (not a big issues as I have a big bilge).
I am planning to polish up the shaft a bit in front of the stuffing box, before I try and slide it, with some emery cloth.

When I get out to the boat this morning I will try to get a couple of pictures.

Any recommendations?

Glenn

[Pete7]

Glen,

I would start here, the website is written by a CF member.

Pete

Re-Packing A Traditional Stuffing Box Photo Gallery by Compass Marine How To at pbase.com

[AZ-Oldguy]

Thanks Pete, very helpful.

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[Sun and Moon]

Shaft should slide back very easily. it is loose enough to turn easily and should slide just as easily. Prop may hit rudder when you slide it back - I need to turn my rudder and tie it off to move it out of the way. Do make sure shaft is clean when you slide it back, or else you will move crud back into the stuffing. It may be time to repack your stuffing box anyway.

[a64pilot]

He's changing engine mounts, not replacing his stuffing box.
I changed my mounts leaving shaft connected, and only disconnected for the alignment, which means moving it back about
.010"
No need to mess with the box, excessive shaft movement etc.
I should ask how long is the shaft?


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[AZ-Oldguy]

I would guess there is more than 3 possibly four feet of shaft between stuffing box and flexible coupling. A64PILOT, how much were you able to lift the engine with the shaft still connected?

Sun And Moon, thanks for reassurance, there is lots of room behind the prop.

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[AZ-Oldguy]

Just an update, we got the shaft cleaned up, the stuffing box lock nut loosened, packing seems in good shape. We can hand dial the rate of drip by turning the box left or right. We un-bolted the shaft from the flexible coupling, and with some patient pounding and prying got them separated and as Sun and Moon said it slid back very easily. So, tomorrow we jack up the motor and swap out the old mounts for the new. Thanks for the good advice.

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