Stuffing box too hot

[whistlerxc]

I know this subject is quite well covered in previous threads and I have looked through them but cannot find a situation that is exactly like mine. I have the traditional stuffing box with locking nut and packing housing. I just recently replaced the packing (the new packing is traditional waxed packing) and screwed on the packing nut. I was pleased to see that I did indeed get some drips of water from the stuffing box (after some adjustment when testing the system while in gear at the dock).

However, once out on the water and after 15 minutes or so the temperature of the box is much too hot even though I am getting a decent amount of drips that ordinarily would be enough to cool the shaft.

The old packing was of what I think was the more modern, but now discouraged to use, material that would be susceptible to galvanic corrosion, so I switched to the old fashioned waxed material. Because the new packing was not the same thickness, I added one more ring which completely filled the space available. Could I have packed the packing nut so full that water will get through but not throughout the space and thus the water is not completely 'circulating' throughout the packing nut and thus causing it to over heat? Or could the packing be so tight that the shaft is overheating despite the water?

I was out of the water when I replaced the packing but now that I am in the water I think I will take a chance and open up the packing nut, remove a ring and quickly replace the nut. Hopefully not too much water will come in!

Any thoughts?

 

[mvweebles]

Your shaft may be scored creating friction. I do not know your situation so can only say what I would do on my boat and you'll have to decide if it works for you in your situation.

I have always done stuffing while im the water. I was surprised how little water came in even with the nut totally backed off and all packing removed. Bilge pump easily kept up. First time I did it I was expecting Ole Faithful and had strips of tee shirt ready to stuff in

I like to "dress" the shaft where stuffing contacts by using some 320 wet/dry sandpaper saddled over the shaft while the engine is in gear and turning the shaft. Yes, this means backing off the compression nut completely to give space to "saddle" the shaft with the sandpaper.

There are better packing materials than traditional flax. Teflon is readily available. GFO is the best. Sounds like you're getting adequate water flow which is a good thing.

Good luck. Please update when you get it solved. Pictures are always a good thing.

Peter

 

[whistlerxc]

Thanks Peter. You have given me an idea as well as some confidence to do some work with the box while in the water. When I first removed the packing nut, I did notice a small bit of scoring on the shaft, but it seemed to me at least, to not be all that bad. I will try your sanding idea.

I do not like the idea of replacing the shaft although I have been told that it might be possible to remove the shaft and turn it end to end. Now that would have to be out of the water and a trip to the yard, so I would like to not have to do even that.

 

[OldDan1943]

Do not use sand paper. Use a wet/dry cloth.
Sand paper will leave grit behind.

 

[whistlerxc]

Got it. Thanks.

 

[Juliet 15]

I just went thru this exact scenario. I thot if 3 rings of packing were good then 4 or 5 was better. Wrong. The friction is too much. I had 140 degrees in 15 min. I pulled out the extra rings so I only had 3. Temps immediately dropped back to 70 degrees. I suggest you remove all and reinsert only 3 rings, with the cuts evenly spaced, then very gently tighten over a couple of operating hours as needed to get the right drip rate. I think your temps will be right on.

 

[Comodave]

We used Duramax in our last boat. Adjusted properly it doesn’t leak in or out of gear. No galvanic damage to the shaft when I rebuild the stuffing boxes, just very shiney shaft.

 

[kapnd]

I’ve seen a lot of stuffing boxes, never seen one damaged by graphite in packing, but have seen plenty of damage from sitting in salt water with any type of packing.
Fresh water flushing before layup helps this, even better if the packing is flushed after every use.
That said, traditional flax packing does go through a break in period, where it runs a bit hotter than normal before it settles down.
If the shaft is damaged, hopefully you have room to use a longer flex tube to move the packing to a smooth spot up the shaft.

 

[Insequent]

Folks sometimes use the wrong size packing, and anyone who ends up with 5 rings is likely in that situation. Too many rings of packing often end up over-tightened to stop drips, and then it runs too hot.

With the old packing removed, use a drill bit to measure the gap for th correct sized packing. Then buy enough for 3 rings of that size. You might only need to use 2. You will probably also have to use a hammer to flatten it a bit so it can be fitted, but trust the label on the packing, and if it matches the drill bit size, just flatten it to the extent you need for it to go in.

I suspect where people go wrong is that they think "this packing is too large a size to fit, I'll use the next size down". But as I indicated above, if you do that you will most likely end up with too many rings, and too much compression on the collar etc

The number of rings used will be determined by the length of the studs in relation to the amount of thread the nut and locking nut need to compress the collar. Not enough rings and the collar bottoms out (two-blocked) before compressing the packing enough.

I'm using the old flax stuff and am happy with a few drips. But there is a type (maybe GFO ?) which is designed to be dripless. In that case its more difficult to get the collar compression just right I think. Over tighten and you risk shaft damage and/or high temps.

I have slow drips and collar temps of 90-100°F. My yard did one rudder and one shaft after going back into the water after last haul-out as they thought they were dripping too fast. Easy to do in the water as Peter noted above. They put some grease on the packing when fitting. You could also do that but should verify the grease you are using is compatible with the "wax in the flax" so to speak.

 

[whistlerxc]

Thanks to all. I will be going down to the boat in the next few days and will use all this new knowledge to make some changes, including doing the changes while the boat is in the water. I will let everyone know of the results. Cheers

 

[Comodave]

Have a few rags ready in case you need to stuff them temporarily while you work on it. The water flow should not be too bad though.

 

[OldDan1943]

Assuming you have a draft of about 3 ft, your bilge pump should have NO problem keeping up.
I suggest and encourage you to use a packing of the PROPER size with Teflon in it.

 

[greatpapabear]

I just went thru this exact scenario. I thot if 3 rings of packing were good then 4 or 5 was better. Wrong. The friction is too much. I had 140 degrees in 15 min. I pulled out the extra rings so I only had 3. Temps immediately dropped back to 70 degrees. I suggest you remove all and reinsert only 3 rings, with the cuts evenly spaced, then very gently tighten over a couple of operating hours as needed to get the right drip rate. I think your temps will be right on.

That's a really good point. Thank you.

 

[rslifkin]

Too many rings of packing or wrong size packing can definitely cause issues. Personally, I've been using a synthetic fiber PTFE packing, but not the graphite stuff (due to the concern about galvanic corrosion). It's been working quite well and is pretty dry (if I actually get and keep the adjustment perfect, it's basically just damp but almost never drips while sitting and just drips a little bit while moving with the stuffing boxes just slightly warm up on plane).



The stuff I'm using is Palmetto 1347AF (cheaply available from Amazon). I also keep a roll of packing and a packing extractor on the boat, so if a stuffing box ever acts up and I can't seem to adjust it happily, I can just repack it on the fly in a few minutes (haven't actually had to do that).

 

[N4061]

A bad experience

Our only bad experience with a stuffing box was with our N35 which we purchased as a used boat (900 hours on the engine). While our story may not be related to your situation its worth mentioning for the one in a million chance. Our issue was not noted as major during the sea trial and I thought a warm stuffing box was something I would adjust it. Weeks later and half a dozen runs, the stuffing box kept getting hot. Took the boat to the yard twice to inspect and repack the shaft only to still have heat issues. Got to the point I was convinced we had a larger problem but unable to figure it out. Decided it was time for a new boat and sold the N35. A few months later the new owner whom I explained the issue prior to the sale called and said he found the problem. The shaft was oversized. How and when this occurred how knows but he reported everything was working fine after replacing the shaft.

Just goes to show the problem can be the last place you look. Best of luck with the repacking in water.

John T

 

[greatpapabear]

We had endless issues with our Fleming 55's stuffing boxes. They'd forever be spitting grease and becoming too warm, regardless of adjustment. Can't remember how many times we had her lifted and the boxes re-packed.

Eventually, after 18 years (!) we found the problem.

The shafts and boxes are imperial and require 3/8" packing material, but in the UK, imperial size isn't available. So, when the yard was ordering replacement material, they were being supplied with closest fit 10mm - very slightly oversize.

When I found this out, I ordered 3/8" GFO Gortex from the States.

Problem solved.

 

[C lectric]

I am another using the Gortex GFO packing. Yes it has the graphite. Installed about 15 yrs ago and the same packing is in play. I tweak once or twice a year as all packings wear but I do mean Tweak.

The shaft was pulled last spring for some work, straightening, and a new coupler and there was NO sign of any degradation of the shaft in contact with the GFO.

Before I tried the GFO I was constantly fiddling, repacking and so on.

I will say though that it took some time to adjust the GFO properly to not overpack it yet control the drips. Long term, to me, it is a far superior product to the older packings.

I'm sure the Duramax is the same, just never used it.

 

[Nepidae]

Packing gland

Here (https://www.defender.com/product3.jsp?path=-1|311|2349117|2349129&id=685625) is a tool to remove all of the packing, the old included. You may need a different size so check that.

Here (https://www.defender.com/product.jsp?path=-1|311|2349117|2349129&id=6719218) is the packing you should use. Stay away from any with graphite as you could experience some dissimilar metal reaction. The size of the packing should be the thickness of the distance from the shaft to the edge of the tube. Offset the cuts by 90 degrees. Try and get the ends to overlap but butt tightly in the minimum.

3 rings may be enough but that would depend on the depth of the gland. Usually if you have too much, your nuts on the gland won't have enough thread for them to bite.

There should not be any drips at rest. Limited 1 a min or so while operating. Use an IR gun to test for temps, can also use the gun for getting other temps in the ER while operating. 70 degrees would depend on outside water temp.

You could also go to Dripless seals. In the long run that may be the best approach. I went with Lasdrop Gen 2 (https://lasdrop.com/) due to the bellows construction. I wanted a solid wall not a billow looking wall. Put ours in in '11 and redid the seals in '16. No leaks.

Any questions, let me know.

 

[ronobrien]

Your shaft may be scored creating friction. I do not know your situation so can only say what I would do on my boat and you'll have to decide if it works for you in your situation.

I have always done stuffing while im the water. I was surprised how little water came in even with the nut totally backed off and all packing removed. Bilge pump easily kept up. First time I did it I was expecting Ole Faithful and had strips of tee shirt ready to stuff in

I like to "dress" the shaft where stuffing contacts by using some 320 wet/dry sandpaper saddled over the shaft while the engine is in gear and turning the shaft. Yes, this means backing off the compression nut completely to give space to "saddle" the shaft with the sandpaper.

There are better packing materials than traditional flax. Teflon is readily available. GFO is the best. Sounds like you're getting adequate water flow which is a good thing.

Good luck. Please update when you get it solved. Pictures are always a good thing.

Peter

Years ago I ran the maintenance dept for an oil tank farm. We had many pumps that had similar packing. We switched from the old cotton/wax packing to a Gortex material. The stuff was fantastic. The difference from the PTFE was that the PTFE was impregnated into a carrying material, whereas the Gortex was just the material itself. I've not dealt with the material in many years though. Here is the CO that we dealt with.
https://ripacking.com/

 

[Bmarler]

Years ago I ran the maintenance dept for an oil tank farm. We had many pumps that had similar packing. We switched from the old cotton/wax packing to a Gortex material. The stuff was fantastic. The difference from the PTFE was that the PTFE was impregnated into a carrying material, whereas the Gortex was just the material itself. I've not dealt with the material in many years though. Here is the CO that we dealt with.
https://ripacking.com/

gortex packing (gfo) has been around for a while. good stuff, and will be what i install when it's time to re-pack.

 

[Dwk]

stuffing box temp

Question folks: What temperature range is acceptable when measuring temperature of shaft and stuffing box while running wirh a IR gun?

 

[mvweebles]

Question folks: What temperature range is acceptable when measuring temperature of shaft and stuffing box while running wirh a IR gun?

I can't give you a temperature, just to say it should not be hot. You should be able to touch it without any discomfort. Depends on sea temperature too.

Peter

 

[Comodave]

Question folks: What temperature range is acceptable when measuring temperature of shaft and stuffing box while running wirh a IR gun?

There is a standard, if I remember correctly, it is about 30 degrees above the water temperature that the boat is in.