Stuck on stuffing box

[bawlmer]

OK. So I decide to replace the packing material in my stuffing box as it has not been done yet since I bought Mystic in 2013. I read all the posts and studied the process to death. I bought the 3/16 flax and today I dove in to get it done. I am having an unexpected problem as I am having a seriously difficult time getting the big nut loose that holds everything in the packing box. All of the threaded surfaces are moving fine. The friction appears to be between the packing nut and the prop shaft. I polished the shaft as much as I dared to reduce friction but I have to really use muscle to move the nut. The threads are fine and nothing is stripped as I moved the nut back up the shaft just to check. I would like to ask the group for wisdom or to see if there is something I need to look out for. I don't want to force this and cause a nasty expensive repair by doing something stupid. As always all wisdom welcome.

 

[JohnVTX]

There is a very thin locking nut on the tranny side. In your picture it looks green.

 

[bawlmer]

There is a very thin locking nut on the tranny side. In your picture it looks green.

John. There is a locking nut but that is already loose and is on the left hand side (aft) of the packing nut. I think the green you are referring to is the front of the packing nut toward the transmission. But I could be wrong.

 

[JohnVTX]

Sorry, you are correct. many people have taken a hard whack with a hammer to loosen.

 

[Charles Erwin]

No hammer yet - please. The packing nut - furthest to the photo right - contains the packing material. Once unthreaded that nut should slide right up the shaft all the way to the shaft/transmission coupler. Are you saying it will not slide toward the transmission?

If it will not move forward perhaps the shaft has worn and the old packing was set into the worn area. You need to slide the nut forward to pick out the old packing and inspect the shaft surface.

In short, there is nothing in the way once the nut is loose from the threads.

Charles.

 

[bawlmer]

That is what I am thinking. I am going to try it again today. I can't believe there is so little clearance between the shaft and the nut. I will report back on my progress.

 

[LakeOntario270]

What size wrenches are you using? I bought a monster 1 7/8" open end wrench on Amazon and a 18" adjustable wrench from Harbor Freight and the packing nut cam off with no effort on my part.

 

[bawlmer]

Yup. I have the same ones you have. I got them from Harbor Freight and the are HUGE. My marina is in an urban waterfront and I got some serious looks as I was walking to the gate with them. I already have everything loose. The problem I am having is that it is taking a lot of effort to continue to unscrew the packing nut. I want to make sure I am not doing something wrong that would strip any threads or damage the shaft. Is this normal? Maybe this is just paranoia but better safe than sorry.

 

[RoyS]

I would separate the coupling before continuing. From the photo it looks as if the shaft log assembly is deflected downward. This could result in significant friction against the packing nut when it reaches the end of the shaft threads. The coupling is easy enough to separate.

 

[Ralph Johnstone]

I would separate the coupling before continuing. From the photo it looks as if the shaft log assembly is deflected downward. This could result in significant friction against the packing nut when it reaches the end of the shaft threads. The coupling is easy enough to separate.

As Roy says to ensure everything is as free as possible.

If that doesn't get things moving, I would still have to suspect that the friction is between the nut threads and the log is the culprit. Try rapidly applying a quick blast of heat to the nut with a torch and then try moving while the nut is still hot. Probably a two man job. Use extreme caution so as to not overheat the hose.

 

[JohnVTX]

This is common with boats in salt Water, Again... hit it on flat part of nut with a hammer. This is from a post on Monday for a Catalina 30, after numerous folks told him to hit it with a hammer. "Saturday I got to the boat in howling wind and rain went below and go to work. A couple of shots of BP Blaster and a few taps with a hammer and the lock nut began to turn. I worked it until it would turn easily over enough threads to adjust. I worked the next 3 hours trying to get the correct drip ratio. but finally got 6 drips per minute, locked it down and ran the engine in both forward and reverse. everything seems to be good but I can see this is an item that needs to be checked often. Again thanks for all the great advise...Brad"

 

[weinie]

Put a monkey wrench on it and wack it gently a couple of times with a METAL hammer. A couple of good CLANGS will cause it to loosen.

 

[Ralph Johnstone]

This is common with boats in salt Water,

As a final note, once you've finished re-packing the gland, lube up the internal threads with waterproof grease (Syntef, SuperLube, etc.) which might make it a little easier next time you take it apart.

 

[Johnb]

Can you clarify whether the packing nut (the big one on the right that has the packing inside) is turning freely on the threads. If not it should be remembered that any torque you put on it has to be counter acted by the rubber tubing.

 

[bawlmer]

Update. I was at the boat all day. I greased the prop shaft with silicone grease and hit the threads with some more PB blaster. The nut finally became loose and I was able to slide it toward the engine. I spent most of the remaining part of the day digging out the old packed in flax. It took 3 solid hours and I went through 4 dental picks. I cut the new flax and started to install it. I now have a new problem. Catalina specifies 3/16" flax in its shaft diagram. When I installed it there is daylight between the flax and the shaft. It looks like the flax should be 1/4" instead of 3/16". This would qualify as a dumb question except the Catalina doc says 3/16". Lowell from Catalina is on Vacation. Shouldn't the flax fill 100% of the void between the inside of the nut and the shaft? All wisdom greatly appreciated.

 

[Charles Erwin]

This will save you time - next time. Use a 2" (or longer) sheet rock screw along the drive shaft axis. Thread the sharp end into each packing ring first - then pry out.

I have the same box as you. I removed 3 rings. When I cut the new 3/16 material I found the same generous clearance. So I decided to use 1/4 PTFE (teflon) impregnated flax. The 1/4 was very tight, thus difficult to press into the packing nut. So I compressed it gently into a thinner section with a hammer. Then set 2 rings of 1/4 instead of the three that came out.

Snap a 1" long piece of 1" diameter plastic pipe (cut down the middle) on the shaft and use that to press against the rings so they get pressed into the packing nut. Pay attention to over tightening - just hand tight plus a tiny bit to start with.

Review this for reference. http://www.pbase.com/mainecruising/stuffing_box&page=1.

Would be very interested in what Catalina says about packing size but Johnstone will know the answer for sure.

Charles

 

[shemandr]

We would be remiss not to tell you that Mainsail has a very good tutorial available on his website, I think, via a link on this site that can be searched for. The horse may be out of the barn and running down the road but it is very informative and would have been a great place to start this project. Go to Musings with Mainsail.

 

[Charles Erwin]

No need to search anywhere further my friend - the review note reference above is the Maine Sail lesson.

 

[Ralph Johnstone]

The 1/4 was very tight, thus difficult to press into the packing nut. So I compressed it gently into a thinner section with a hammer. Then set 2 rings of 1/4 instead of the three that came out.

You definitely want the flax to fit snuggly within the gland while packing. If not, you will be pre-compressing the packing and it will be already hard when it contacts the shaft. Makes for poor sealing so, you will have to tighten a little further, which leads to overheating, which makes you back off a little bit, which leads to more leaking, ................................................. You get the picture.

 

[bawlmer]

Thanks to everyone who responded on this thread. I read Maine's article (again) on replacing packing flax and ordered his recommended stuff from Hamilton Marine. It won't be here until next week so I have a while to stew over this. The good news is that I get the hard part (hopefully) done. I will be out of town next week so I will not be back to finish the job until next weekend. I will follow up with Catalina just to see why they specified 3/16" material. This was a real PITA but so far a great learning experience and after buying flax twice still zillions less than what the yard would charge. I will update again when I finally get this job completed.