Q2 - Stern Gland.. green corrosion, nuts seized, brass??

Richard10002

Richard10002

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What started as replacing a wire from the stern gland to the anode has become a bigger job!

The stern gland housing seems to be brass, and it is one of those where you tighten 2 bolts which force a kind of tube, (gland follower), onto the packing... just like fig. 5 here:

http://www.diybob.com/diyPackingGland.htm

QUESTION - The whole thing is covered in a green type of corrosion, which I guess I could brush of with a Dremel and a brass wire brush??? Also is there something I could soak the nuts and bolts in to free them up, or id brushing and greasing the way to go?


QUESTION - If I remove the gland follower, will water come in.... if I remove the packing to replace it, will water come in. i.e. does repacking the stern gland need to be done whilst out of the water?

QUESTION - How can I tell what type and size of packing I need?

many Thanks

Richard
 
As DIYBob says --"It is preferable to replace the packing material when your vessel is out of the water, but if you can no longer control the leakage and don't want to haul your boat out, you can stop the water from entering by putting Play-Doh or putty into some kitchen plastic wrap and rolling it into a cigar shape. Dive under the boat and jam the plastic plug around the shaft, forcing it up the shaft tube. This will slow the leakage while you replace the packing. Don't forget to remove the plastic plug, without water for lubrication the new packing material will burn up".

Personally I would go for the boat out of the water, I think Bob must sail in Florida!

Corrosion will brush off.

Get some Plusgas or similar on the nuts if necessary.

Size of packing - best measured when the gland is apart, or ask another M44 owner? There are various kinds, but the standard stuff from chandlers works.
 
The green stuff is probably no more than a surface patina, it will usually clean off fine with a rub and some grease.

The PC answer to the packing question is that you need to replace it out of the water. However, there are further points.

Firstly, why are you replacing it? If you are certain that you need to, because tightening the nuts does not prevent leakage, then fair enough. If you are doing it because it seems like a good idea, then don't. Packed glands are very reliable and long lasting. Mine has never been changed in at least 14 years, maybe more, although I have had the shaft out several times. When tightening the gland nuts don't overdo it, make sure the shaft still turns freely and check it when it's running in case there is overheating.

Then, it is possible to replace the packing in the water if you can stand a bit of leakage into the boat and don't panic. The hardest part may be getting the old stuff out, you will have to hook it with a wire. Bear in mind that wrapping a rag around the whole thing will stop almost all water from coming in while you have a rest or take stock. Make up thenew packing rings before you start, cut accurately with a chamfer on the ends. Stagger them around the circumference when refitting. If the inflow seems to be excessive leave the final ring in and just replace the others, then do it again when you are hauled out.
 
Very Kind... Others would have suggested that I RTFM, (or web page in this case).

Glad I'm not a Yachtmaster <g> (Sailorman and Sticky will know what I mean)
 
You can't tell me one I haven't heard! /forums/images/graemlins/blush.gif
 
[ QUOTE ]
Dont undo the nut the wrong way

[/ QUOTE ] In this case it is a gland follower tightened by two bolts (or are they nuts on studs) so not at all likely to be left handed.

If this job has to be done as an emergency while afloat it may be sufficient to just replace one turn of packing but do a proper job when it can be done ashore or at least dried out.

Remember that when tightening the gland you must allow just a very, very slight leakage. If you tighten it to completely stop all leakage the loss of lubrication and cooling will result in the gland overheating!
 
Gland follower with nuts on studs... clockwise to tighten.

I wasnt originally considering replacing the packing, just thought it might be an opportune time to do it... obviously not!

Got the studs out and the nuts off. Cleaned one up and put it back on... waiting for the drill to charge to clean everything else up and get the second stud back in.

Any ideas what will be causing the corrosion... electrical or just sea air?

Cheers for the help

Richard
 
I've got something like that on my boat. It should be bronze and the colour doesn't matter as long as it's working. I found that removing the screws, pulling the front end up the shaft and fingering in lots of grease before re-assembling was fine. Trick is to tighten the nuts very gently with the shaft turning so that you get mimimal drips with no overheating. If you overtighten, you'll need a new shaft soon. There should be castellations or wire-holes in the nuts so they remain in place once "tuned". (warm to the touch at cruising revs should be OK) All this really has to be done afloat, water ingress is negligable, if your bilge pump doesn't sense or can't cope now's the time to find out!!
 
Sorted! (I think). Got the nuts and bolts freed up, cleaned of a lot of the corrosion....

I think the follower was corroded to the body of the gland.

When I got it off, a slow drip of water began, which increased as I tightened up the follower, then stopped.

So it's tightened to a distance of 6 threads each side, and I'll see whether it drips every 30 seconds or so with the engine ticking over tomorrow.

From what people have said, I can adjust it while the engine is running to get it right.

Thanks for all the help.
 
OK, propshaft turning at 1000 revs, initially a kind of thick brown liquid form around the shaft where it enters the follower - no drips!

Unscrewed follower about a quarter turn, no drips - tapped the follower with a hammer, in and out, drips every 3 seconds +/-.

Bit of trial and error, I've got it to a drip every 10 seconds +/-, gland housing hot to the touch, but just bearable.... any tighter and no drips, just the thick brown stuff collecting around the shaft .

360 drips an hour.... hopefully that's OK?

Any comments welcomed.

Thanks to all for the help

Richard
 
Richard
She won't sink!

But expect to get some water in the boat.

As for cutting the new packing just wrap the whole lot round the shaft between the stern tube housing and the gear box coupling and then cut it on an angle - you should get between 3 to 5 nice little rings just the right size.

You could consider removing only say 3 pieces of the old packing then insert the new, this will mean you don't get any water in the boat - then wait until you can dry the boat out to fit the remaining coils.

Peter.
 
Thanks for that... I'm not going to worry about the packing for a while, it looks OK.

When I got the follower off, the packing is only about 3mm +/- inside the gland, so seems OK.

I think it's sorted for the time being.

Cheers

Richard
 
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