The boatyard installed a new stuffing box and stainless shaft in my boat this spring, and I have had a few challenges and questions. Perhaps someone, especially
, could provide some advice.
The one they installed is shown here. It came pre-packed with Teflon impregnated packing material:
Unit comes complete with a packing nut and jam nut. It is also pre-packed with 1/4" composite fiber packing material. A high-tech non-asbestos replacement for your original flax packing. The fiber is impregnated with virgin PTFE in-suspension and internally saturated with a proprietary lubricant.
Substantially less abrasive than asbestos, yet still able to withstand temperatures up to 500 degrees F. Excellent watertight sealing ability with less required leakage at rest to compensate for frictional heat expansion when under way. An ideal replacement for standard flax packing, this packing can be adjusted to drip only once every three minutes (while at rest) compared to the typical 2 to 3 drops every minute required for flax packing.
First, I have had a real problem getting it adjusted to drip properly. It's either completely sealed, or running a small stream. It's almost impossible to get something in between. On the couple of occasions when I've gotten an appropriate drip, it always seals up in use, presumably due to thermal expansion. However, even when sealed, it has never gotten very hot - always below 95°F or 100°F. But nevertheless I am concerned about abrasiveness if it does not get enough lubrication.
Also, I am concerned that even when the water is leaking in, it is not flowing between the packing and the shaft, but instead through the threads. I see no sign that it is coming through the shaft, like my prior packing did. In fact, a few weeks ago I noticed the beginning of some dezincification on the threads where the water was contacting them, so I did an acid clean to get away all salt deposits. I decided to apply a little synthetic grease to the exposed threads and under the locknut to inhibit water intrusion, but did not put any grease on the threads under the primary nut. After doing that, the water leakage can be significant when the locknut is loose, but is ZERO when the locknut is tightened. To me this is a sure sign that the water is coming through the threads (when the locknut is loose), but when the locknut is tight (even just hand tight) the grease seals up the leakage through the threads.
Obviously, if water leaks through the threads, the stuffing box is being cooled, but without the water passing along the spinning shaft it is not providing any lubrication.
In a last ditch effort, I made the locknut hand-tight and loosened both lock nut and packing nut together. No leakage occurred until the point where the packing nut disengaged from the threads, and then the water POURED in until I was able to re-engage the nut on the threads. So I am finding no way to get any lubrication water through the shaft seal without sinking my boat.
Any advice on what I can try next? I have only 25 motoring hours so far, so I assume it is still breaking in.