15-APR-2007
The Stuffing Box (click any image to see a larger version)
A few weeks ago, while digging around in some old boat parts boxes, I found the stuffing box from my old Catalina 36. It was sitting in the parts box because I had chosen to replace it with a PSS Shaft Seal to make my bilge totally dry. Today is a rainy Sunday and I though it would be a good time to rig it up in my garage and photograph how to replace the flax packing inside one of these "work horse" style stuffing boxes and add it to my "Boat Projects Gallery".
For illustrative purposes I cleaned the stuffing box of it's oxidation and grime with my drill press and a wire brush. I used a piece of 1" diameter stainless steel as my makeshift prop shaft to complete the picture and present this as it would look inside a boat.
In this picture what you are actually seeing are two nuts not one. The larger of the two is where the flax resides. The thin nut, on the left, is the locking nut. Once re-packed, & properly adjusted, you lock these nuts together with two large wrenches. If you don't lock these nuts down tight enough, meaning the nuts are each tightened in opposite directions against each other quite tightly, you run the risk of the big nut backing its self off the threads when you put the transmission in reverse. There have been more than a few boats sunk by improper tightening of the stuffing box nuts! Just ask the Boat US insurance division.
15-APR-2007
Stuffing Box Wrenches
This picture shows the wrenches I use to loosen and tighten a stuffing box. One wrench is a traditional pipe wrench and the other is a spanner wrench designed for a sink drain. Both of these wrenches are available at Home Depot or a hardware store. I find it easier to use the pipe wrench on the small & thin locking nut and the spanner wrench on the big nut. It's very important to use wrenches that fit the nuts well. Water pump pliers will, in many cases, not work very well or will not get the nuts tight enough after adjustment. Use good wrenches and not pliers for safety's sake.
If you have tried the above method and the nuts don't break apart use a little bit of PB Blaster penetrating oil. Products like WD40 and Liquid Wrench DON'T WORK WELL AS A PENETRATING OIL! I can't stress enough how much of a difference there is between a product like PB Blaster or Thrust and lousy products like Liquid Wrench and WD40.
Here's a direct quote from a guy who used this site for directions. Unfortunately after three hours, Liquid Wrench and a broken tool he gave up and emailed me for advice:
"I knew where the cap and the locking nut were, I just couldn't budge them. Went out and bought PB Blaster. Ten minutes after spraying it broke loose. PBB rocks!"
WARNING. WARNING, WARNING!!! Be very careful NOT to get PB Blaster near ANY engine or transmission seals. True penetrating oils will EAT engine seals causing catastrophic failure of that seal. The most common seal DIYers destroy is the transmission output shaft seal. Be very, very careful using PB Blaster on your engines coupling bolts and DO NOT use the spray feature when working that close to seals. If you need to use a penetrating oil on coupling bolts fill the PB Blaster cap with the penetrating oil and then use a Q-Tip to dab PB Blaster on the bolts being very careful not to drip ANY on or near the transmission output shaft seal.
15-APR-2007
Getting The Stuffing Box Nuts Apart 2
Here's another view of the wrenches and the process. When loosening the nuts the two wrenches are moved towards each other. When tightening the nuts the wrenches are moved away from each other as shown here.
15-APR-2007
Broken Free
In this photo it's much easier to see the two distinct nuts. Again, the thin one on the left is the locking nut and the big thick nut on the right is the stuffing/flax nut.
15-APR-2007
Bolts Loose
This photo shows the threaded male end of bronze stuffing box and the flax nut or the female end of the stuffing box separated from the male end. The white PVC pipe is my mock up of a fiberglass shaft log.
The rubber hose connects the bronze stuffing box to the boat and must be replaced periodically. If this rubber hose cracks, and starts leaking, it could sink your boat. Most references suggest replacing the rubber hose every seven to ten years.
15-APR-2007
Stuffing Nut Shown WIth Old Flax Still In It
When you are replacing your flax packing you will most likely never see this view unless you remove the transmission coupling and take the nut off. When removing the flax, with a pick, this is what you are trying to dig out! I took this photo to show the female nut with the old flax still in it. You can see the shiny surface where it meets the shaft and the thickness (3/16) of the flax its self. This particular stuffing box is a 1 inch box from a 1985 Catalina 36 and uses three rings 3/16 flax packing. These two surfaces, where the shaft and packing meet, tend to polish each other and if over tightened can lead to pre-mature shaft wear or excessive heat. Over tightening of the flax nut, and running the stuffing box with no water drips, will eventually wear a grove in the prop shaft and ruin it. It's very important to allow a few drops of water per minute, when the shaft is spinning, for lubrication. Even the newer synthetic W.L. Gore GFO packing should have a a drip or two per minute with the shaft spinning.
15-APR-2007
My Home Made Pick
I can't remember where I found this pick, perhaps Sears, but it used to be straight and was designed for removing engine seals! I used a blow torch and a bench vice to create my own, custom made, flax removal tool and it works remarkably well. Even a sheet rock screw can be used to remove flax but in tight spaces it's nice to have a couple of bends in your flax removal tool.
15-APR-2007
Getting Ready To Dig Out The Old Flax
In this photo I left about an inch between the male end of the stuffing box and the female nut. This is typical of the space you'll have on many production boats like the Catalina 30 & 36. If you have not attempted this type of DIY job before it's best to do it with the boat out of the water for obvious reasons. With the female flax nut removed water will flow in to the boat from between the male end of the box and the shaft!
15-APR-2007
Grabbing The Flax
What you can't see in this picture is that the sharp end of my pick is firmly embedded into the first flax ring and ready to pull it out of the nut.
15-APR-2007
Removing Flax With A Pick
Success! The first flax ring is on its way out!
15-APR-2007
Packing Nut Off & Old Packing Out
I don't advise, and can't with a good conscience, suggest the use of "miracle lubes" such as "Syntef Stuffing Box Lubricant" the moldable packings like the "West Marine Moldable Packing Kit". While some have claimed good success with these miracle clays or lubes i did not. On my C-36 I installed the "West Marine Moldable Dripless Stuffing Kit" and it was a nightmare. The green stuff in the picture is the "moldable clay" shown with the two rings of Teflon flax that came out of my female flax nut. Read below for more info on why I had problems with this stuff!
15-APR-2007
Packing Nut Showing Syntef & Teflon Flax
The idea behind this green "moldable clay" is that it will make your traditional stuffing box dripless. To install it you insert the first ring of flax, then pack in the green clay like substance and insert the second ring making, in essence, a green stuff sandwich. While the idea of a dripless shaft seal is not new this stuff is probabaly not the ideal way to go dripless! Not only is it very, very tough to remove with a pick, and replace once installed, it also did not work as advertised for me. This stuff can plug the male end of the stuffing box with a thick black sediment as I found out. This sediment can only be described as, remnants of the "syntef lubricant" and the "moldable clay". This gray/black goo totally plugged my stuffing box essentially preventing any cooling or lubricating water from getting to the female nut. If left alone for a long enough period it could wind up ruining your prop shaft!
Click page two for the rest of the instruction!
