Overheating packing gland - what should I do ?

[ribbony]

Finally we have some mobility after two years of restoration. However we ran into a problem. The packing gland / stuffing box gets really hot while motoring about 1 km down the bay from mooring to jetty. The first time it happened it seized up and only turned after it cooled. I loosened it off quite a lot, the shaft turns easily by hand when it is cold. Then the next time we did the run (today) it happened again, not as fast but still it seized. What ended up turning, was the brass stuffing box turning in the rubber hose connecting to the stern tube.

When I assembled the shaft I used a lot of lanotec grease, as a result of that we have not seen any water drip from the shaft to date.

Any ideas on what is happening and just how hot do the stuffing boxes get ?

[never monday]

stuffing boxes shouldn't get hot. Let alone seize. I'd repack it without the grease and set the drip rate to 4-6 gtts a min with the shaft rotating and dry when stagnant.

[pmeyer]

I used GFO fiber dripless packing (Virtually Dripless Packing by Gore GFO) when we repacked the stuffing box the year before last on our 73 Cat 27. It works great - virtually no drips and it runs cool.

Some thoughts based on that experience:

The biggest challenge was getting all the old packing out of the box. This requires persistance and experimenting with a number of tools. I finally used a short piece of wire coat hanger, custom bent and ground to a point.

Measure the actual size of packing you require. The web site says I probably need 1/4 packing for my 1 inch shaft. 3/16 was the correct size.

Expect the adjustment process to take some trial and error on the water. I started quite loose with a few drips and slowly tightened. Also it seems to take a while to seat. It took several (5-8) adjustments over two hours to get it perfectly adjusted.

I consider perfectly adjusted (with this packing material) to be as close to no drips as possible with the stuffing box cold to the touch after 15 minutes of full throttle motoring. Depending on the condition of your shaft you'll need to tolarate an occasional drip. Its VIRTUALLY dripless.

My limited experience is that with conventional packing a cool stuffing box would require 3 - 4 drips a minute.

Also check out the best explaination of this process that I have ever seen:
Re-Packing A Traditional Stuffing Box Photo Gallery by Maine Sailing at pbase.com

Paul Meyer
Fredericton New Brunswick Canada

[Zach]

The only time I've seen that, is when the packing was just spiraled on, instead of rings that butt up at 45's around the shaft. Tried to tighten up like a boa constrictor, then once the nut was tightened it may have well been a solid wad of packing.

On boxes of a decent size, a real thin pair of needle nose are helpful. That and a thin knife to reach in and slice up what you can, thread in the puller and yank out a sliver at a time. Hook picks of various shapes and sizes are real nice to have around too.

[GordMay]

Packing Hook and Packing Iron:

[Alan Wheeler]

lanotec grease,
That will be your problem. It is not a lubricating grease. It will bind.

[ribbony]

Packing is individual rings, and it is new.

How to remove the lanotec grease is the question. The only way to remove the packing nut is to remove the engine or slip the vessel and pull the shaft out backwards. there is 12mm clearance between the packing nut and the rear of the shaft coupling (so the nut can not be removed to add packing). It is far from ideal, but before our modifications there was 4mm clearance.

Should the packing still be OK, so it is a case of removing the grease.

I remember seeing stuffing boxes with grease nipples attached (not on ours though), so what is going on with those arrangements.

[Zach]

Wow thats tight! Way to much work...

I'm pondering... pull the set screw on the shaft, tie a rope to the prop and slip the shaft back enough to pull the coupler. Would have to align it, sounds like you gotta do that no matter what, but doing the socket between the halves and tightening up the bolts is a lot easier than pulling the engine.

(I'd be tempted to knock in a plug and hop back onto the dock shaft in hand screaming "It just fell out" )

How long is the hose coming off the shaft tube/shaft log, or is it all one casting?

If you can get the shalt half of the coupling off, I'd drop it off at a machine shop and have them take a little off the shaft side to gain some space (given the prop doesn't slide forward and hit anything.) 1/8th inch off the shaft side of the coupler would be 3.175mm.

(I wouldn't take off the transmission side of the coupling. Had the nut that holds that one on, fall off. Not going anywhere when that happens!)

While your at it laying the flat side of the nut on a belt sander until it looks a little thicker than to thin...

[island trader]

can you not trim the rubber hose? after the stuffing box spun the rubber, I would be for trimming it, get some new rubber on the stuffing box. most rubber tubes I have seen have room to trim. sharp knife and wire cutters. then drive the box deeper, giving you room to work.

[Chief Engineer]

Only had one problem...but that was on a large shaft.....W.L. Gore suggested putting in a water cooling fitting for the stuffing box.....voila'

Originally Posted by pmeyer

I used GFO fiber dripless packing (Virtually Dripless Packing by Gore GFO) when we repacked the stuffing box the year before last on our 73 Cat 27. It works great - virtually no drips and it runs cool.

Some thoughts based on that experience:

The biggest challenge was getting all the old packing out of the box. This requires persistance and experimenting with a number of tools. I finally used a short piece of wire coat hanger, custom bent and ground to a point.

Measure the actual size of packing you require. The web site says I probably need 1/4 packing for my 1 inch shaft. 3/16 was the correct size.

Expect the adjustment process to take some trial and error on the water. I started quite loose with a few drips and slowly tightened. Also it seems to take a while to seat. It took several (5-8) adjustments over two hours to get it perfectly adjusted.

I consider perfectly adjusted (with this packing material) to be as close to no drips as possible with the stuffing box cold to the touch after 15 minutes of full throttle motoring. Depending on the condition of your shaft you'll need to tolarate an occasional drip. Its VIRTUALLY dripless.

My limited experience is that with conventional packing a cool stuffing box would require 3 - 4 drips a minute.

Also check out the best explaination of this process that I have ever seen:
Re-Packing A Traditional Stuffing Box Photo Gallery by Maine Sailing at pbase.com

Paul Meyer
Fredericton New Brunswick Canada

[Chief Engineer]

Correct me if I am wrong....but there shouldn't be any "wire" in a stuffing box hose.

All the stuffing box hose that I install is specially designed for that purpose.

[ribbony]

There is wire in the hose !

The shaft half of the coupling is held on with a nut on a tapered shaft. The coupling was made too long but that is another story and it can not be shortened due to the taper. To remove the coupling we also have to pull the engine (it is a real pain). In retrospect we should have bought a cheap off the shelf coupling and had a new prop shaft made with a straight end instead of the taper.

The hose has a gap of ~3/4" between the two components, also to replace the hose the engine must be pulled, etc.

Gee, one of those contencious PPS or deep sea seals would be a blessing in this situation.

I will try to put a photo on as that is worth a thousand words.

[DeepFrz]

I don't want to hijack this thread but I saw a picture (preliminary computer model) of Steve Dashew's new FPB 64 engine installation. Here SetSail.com - the serious cruising sailor's website

I was wondering how one would change that dripless shaft seal. Looks to me like the V drive or engine would have to be pulled. I would sure hate to develop a leak in the seal at sea.

[ribbony]

Picture did not work. Here is a link to the photo: Project Yacht

[cooper]

Hi Ribbony...can you undo the shaft flange to vibration damper bolts, remove the damper and slide the shaft flange up until it is hard against the output flange ? This would give yo and extra 30 mm or so ......