Stuffing box threads

S

shawnpb

Active member
Joined
Sep 16, 2020
Messages
38
Fluid Motion Model
C-248 C
Hull Identification Number
FMLT2544G708
Vessel Name
MOKUHONU
I'm hoping someone can confirm the direction I need to turn the stuffing box locking nut to loosen it. I need an adjustment due to excessive dripping. Are they standard threads or are they reversed. I've been told both by folks on my dock. Fighting some corrosion so it's tight & I need to confirm. Thanks in advance!!
 
You have a Marine hardware stuffing box with standard threads. Facing aft you will turn the locking nut clockwise. Use a good penetrating lubricate and saturate a rag with it. Spray the gland And wrap the rag around the gland to help saturate the threads.Use a small ball pean hammer to shock the nuts to help loosen them. Once the locking nut is loose back it off as far as the threads allow. Clean the threads and then work the locking nut all the way back to the packing nut. You are chasing the threads cleaning them. Back the locking nut off the packing nut 1 turn. To tighten the packing turn the packing nut 1/8 turn at a time clockwise facing aft. Check the packing drips with the engine running in gear. Adjust in 1/8 turn increments until achieving 1 to 3 drips a minute in gear engine running.
 
Thank you soo much for your insight. Very helpful. I'm struggling with breaking the locking nut free. I'm soaking it with PB Blaster and begun tapping the nut with a small ball peen, but no luck so far.
 
I'm struggling with breaking the locking nut free. I'm soaking it with PB Blaster and begun tapping the nut with a small ball peen, but no luck so far.
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.

Been there, done that... still doing that. Hoping persistence eventually pays off. Gary
 
I adjusted mine for the first time and found that a pvc pipe installed over the wrench handles gave me just enough leverage to break the nut free.
 
Thanks!! In process of building some leverage with a pipe over my wrench handle. Back at it!
 
I adjusted mine for the first time and found that a pvc pipe installed over the wrench handles gave me just enough leverage to break the nut free.
Click to expand...
I did the same using a 5 foot steel floor jack handle... nuthin. Still banking on persistence...
 
I do not recommend this approach unless you are careful and understand the safety requirements. This is a last resort but works with Bronze. Use heat, Bronze expands at a fairly low temperature. The heat needs to be a quick heat so the nut expands more than the gland. As the nut is heated it opens the thread contact points which have corrosion build up. This helps to get some the penetrant into the threads. You do not want to get it to hot because the heat will sync into the Log and packing. Try to keep the packing and log from heating up over 200 F. I have been successful with this. When I worked on boats in Massachusetts I was an outboard / sterndrive Mechanic. The aluminum alloy components with stainless steel or carbon steel fasteners would be a bear to loosen. The Cutlass bearings in the struts would be stuck and even with a great deal of force would not push out. I quickly found that keeping a small torch strapped to my tool box was a needed tool. I learned quickly after snapping off a few fasteners or having to remove a strut to put it in a 20 ton press to remove the bearing that heat was my friend.


I highly recommend if you use this approach to make sure you have a clean bilge, a welders fire blanket to place under the gland and shaft and place a small piece of the blanket over the packing log hose to protect it. Use a temperature gun to continue to monitor the temperature of the packing nut and the gland. The locking nut needs to be the heat point and the other components should only see heat from the heat syncing. Do not do this if you do not understand the safety aspect of this or do not know how to use a torch.

This is a last resort attempt. It has worked for me. Two weeks ago I replaced the cutlass bearings on my my boat. I removed both shafts and made a puller to press the bearings out. After several attempts I quit. I did not have my torch set with me. The next day I brought the torch and evenly heated the strut keeping my hand on the upper section of the strut. When I felt the upper section of the strut getting warm I checked the temperature at the area where I was heating ( Bearing location) was just over 200 F the upper section temperature was creeping up. I then applied pressure with my puller and the bearing started to pull out of the strut. I worked quickly and had the bearing out with in 30 seconds.

If you attempt this be careful and good luck.
 
A couple gentile taps with a hammer may cause stiction to read loose.
Years ago could not lessen, mechanic tapped and loosened locknut and tightened nut with hands!
 
Good details / technique Brian but beyond my pay grade at the moment. If my persistence doesn't work, I'm going to try a heat gun being careful not to ruin the packing or shaft log. I'm also going to try and fashion a shield to slip between the locking nut and gland to prevent heating the gland too quickly - the locking nut is much smaller and it seems likely difficult to focus the heat on just it without affecting adjoining parts. G
 
You might try using a crow’s foot wrench of the appropriate size. You can then put an extension that runs parallel to the shaft, allowing you to use a much longer handle which will give you the leverage needed to break the nut free.

Gordon
 
...allowing you to use a much longer handle which will give you the leverage needed to break the nut free.
Click to expand...
I used quite a long pipe for leverage and all it accomplished was slight movement in the shaft log hose, which I was warned about disturbing in a separate forum thread (Brian I think). Not forcing things by getting bigger gear isn't always the best solution. I'll keep rat-a-tat tapping for the time being. G
 
So after many soaks with PB Blaster and a lot of light tapping, the lock nut finally loosened. i was able to clean the threads and then start loosening the main stuffing box nut. It looks like I was able to tighten enough to stop the consistent dripping, it was almost a light stream. Now I'm consistently seeing a drip every 20 seconds or so. I still need to check it under power. Thanks to all for the recomendations....SO much appreciated!
 
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