Stuffing box not dripping

[MJH]

Originally Posted by Tmacmi

I had the yard re-stuff the stuffing box this season. It was a tight fit but they got 3 loops in. When I ran it, no water was coming through the stuffing to lubricate it. I put a few hours (10 or so) on the engine to see if that helped bed them and allow for a few drops of water every minute.

Didn't work.

I then tried to loosen the nut, thinking it was too tight. As soon as I did water started coming in the thread side.

I let the yard know and they tried removing 1 wrap, leaving 2, and no water.

They removed another wrap, leaving one, and after about 3 more operating hours there is still no water coming through the stuffing and the shaft.

The yard said they haven't seen anything like it.

Its simple 1/4" PTFE Flax. Also a brand new shaft.

Before installation I measured the interior diameter of the nut vs. the shaft and it was slightly, very slightly smaller than 1/4", but certainly not 3/16.

Any suggestions?

How many wraps did they take out? Sounds like they didn't. I would have them redo the job...somethings wrong.

~ ~ _/) ~ ~ MJH

[Dougtiff]

I adjust the packing to about 4 to 6 drip's per minute, year's ago, i purchased a sail boat that was about 15 year's old,before i knew that some water should be exiting the packing, i was motoring , and the prop shaft broke, upon inspection, you could see the crystallization on the stainless steel shaft, with shiny metal right at the center, where it finally broke, it took many year's for the heat to damage the shaft, to the point where it finally broke, it was a pain in the ass, as i was trying to get from Thailand down to Malaysia via the malacca straits, with no wind, laid out there for a week, before some wind finally filled in and i was able to get to Penang, for a replacement shaft, thats another story, all done afloat.

[Tmacmi]

Originally Posted by MJH

How many wraps did they take out? Sounds like they didn't. I would have them redo the job...somethings wrong.

~ ~ _/) ~ ~ MJH

They took out 2 wraps. I saw the material myself.

On my last trip the temperature on the shaft was 105 degrees with the water temp of 70 degrees

[a64pilot]

Originally Posted by Scorpius

I was told by one "expert" to use the old-fashioned linen packing because PTFE (Teflon) is harder and will wear the shaft much more than linen.

Anything new always is met with scorn and it’s no good.
However there must surely be some draw back to Teflon packing, or why hasn’t it been pretty much universally accepted?
Is it that most just don’t know or don’t care?

I’ve been running it for three or maybe four years and after the initial run in, haven’t had to touch it, sure seems to be the answer to me.

[Andreas W]

The PTFE packing has been around as a gland packing for valves at least since I was an apprentice engineer 40 years ago. I actually can't explain why it has not been more widely accepted for use in stuffing boxes.

[gonesail]

the packing should drip some when the shaft is turning. otherwise the PTFE will heat up and become hard .. then you will either get too much water coming in or you will etch the shaft or both. that was my experience

[bcguy]

Originally Posted by a64pilot

Anything new always is met with scorn and it’s no good.
However there must surely be some draw back to Teflon packing, or why hasn’t it been pretty much universally accepted?
Is it that most just don’t know or don’t care?

I’ve been running it for three or maybe four years and after the initial run in, haven’t had to touch it, sure seems to be the answer to me.

Replacing packing underway and looks like ptfe for this go round from what I read here. Mention was made of a lubricant for this. I asked the chandler here answering "never heard of it". Do I need this lubricant ?


.... thanks