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Re: Stuffing Box
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Jeremy,
Thanks for that.? I will have to respond with what I think I remember about what I think I learned back then.
We had just replaced the cutlass bearing, drive shaft, stuffing box, hose clamps etc and I am pretty sure I put 1/4" packing in my packing gland while my boat was on the hard and I couldn't test it out properly.? Maybe I didn't clean out the packing nut well enough but I found it difficult to insert the 1/4" packing into the nut but I eventually succeeded.? After tightening the stuffing box and running the engine (once back in the water) for a bit I discovered that the stuffing box was starting to get a bit warm and it felt to me like the engine was fighting the pressure on the shaft created in the stuffing box.? I am sure I tried to adjust it but found that it was either too tight or dripping too much if loosened.? Too much torque on the shaft log hose can help cause it to give up the ghost as well.?
I reasoned that the stuffing is meant to be compressed in the stuffing nut which would cause it to expand slightly but at the same time allow some water through.? I also didn't like the idea of friction creating heat in the stuffing box.? My current working ASSUMPTION is that the O.D. of the stuffing box packing is in fact 1/4", but when you tighten down a few threads on the 3/16" packing it sneaks right up on 1/4".? It solved my "stuffing box getting hot" problem and the engine seemed to run with less strain.
Part of the MaineSail (MarineHowTo) page on stuffing boxes does mention how heat from friction here could potentially get quite hot (300f) if water were unable to get through it as the cooling/lubricating substance it is intended to be.? I have not heard of this happening on a T27 but I do think of the stuffing box as a fairly delicate assembly made of incredibly strong parts (bronze, graphite ...) with the weak part being the rubber hose (which probably has closer to a 20 year maintenance cycle) while I am certain that my stuffing box (bronze) was about 45 years old when I re-used it.
Just my experience and $.02.? Your mileage may vary (ymmv).
Best,
Caleb D.
T27 #328
-----Original Message-----
From: jeremy@... To: [email protected] Sent: Thu, Nov 12, 2020 9:30 pm Subject: Re: [T27Owners] Stuffing Box Caleb,
Alas. I am going to ask. I have repacked my stuffing box twice -- once in the water, and again when I replaced the entire stuffing box with a brand new one. According to the manufacturers website, the new stuffing box I am using does require 1/4" stuffing. However, I feel like packing the new glad was much harder than when I did it the first time. However, I have no records as to what size I used for the first time. (But, then I got smart and started keeping records, which is how I know I used 1/4" the second time).
Since the second time was with a new shaft and a new stuffing box, I wondered if the difference was that I used a different size packing material, or if it was just that everything was new.
I have not relaunched since I repacked, so I can not report on how it works in practice.
Here is my data saying that 1/4" is the 'official recommendation':
I can see you have been recommending the 3/16" over the 1/4" for at least 8 years,
I guess I am wondering if your recommendation has always been contrary to what the manufacturer recommends, or do I actually have a slightly different setup?
Given that I just paid for a new prop shaft, I am inclined to re-repack with the 3/16" and only re-re-repack with 1/4" if it seems to be dripping too much.
- jeremy
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