Re-packed Stuffing Box, Unexpected Behavior

[dkinzer]

I just completed a short term (6 hour) haul out during which I replaced the strut and prop shaft anodes, changed out the stern tube hose and re-packed the prop shaft gland. After we were put back in the water and while the engine was warming up, I removed the plug from the gland to let the air escape (and a bit of water afterward) and tightened the packing nut to a torque that felt similar to what had been on it with the old packing.

When we headed away from the dock, I checked on the stuffing box several times and it wasn't dripping at all so I loosened the packing nut several times but still no drips with the prop shaft turning. The temperature of the nut was steady at about 85* and the shaft steady at about 90*.

My question is whether it is normal for new packing to not drip for a period of time and, if so, how many hours should I give it? I suppose that it is possible that I tightened the packing nut too much initially and now the packing isn't relaxing very quickly, if at all.

Thoughts?

 

[Tally Ho]

What sort of packing did you use?

my 2 cents…. Maybe you tightened it enough to really compress the new packing in place, and it will take a while to work into place. But I have never had that happen. That’s why I am curious about the packing. I have used the older style waxed flax and the newer graphite impregnated packing…

Maybe with the boat tied up, even with the engine on and prop spinning, it wasn’t spinning fast enough to generate much friction or water flow.

let us know what sort of packing.


Greg

 

[dkinzer]

I used the PTFE-impregnated flax packing. I'm pretty sure that's what was in there before since there was a partial package of it aboard when we bought the boat.

 

[Tally Ho]

Should be good stuff. I would run it a bit, keep an eye on the temps (they seem cool) and see if it loosens up some.
Before I switched to a Volvo Penta dripless stuffing box, my PTFE packing could be run pretty much dripless without getting too hot…but I tried to keep a little drip to cool it.

But I will say I am a big fan of the Volvo dripless…. So simple, and totally dripless.

Greg

 

[Ralph Johnstone]

Not that unusual if you know what you're after. You must have a shaft with a mirror polish under the packing.

I caught on to this a few years after I purchased my boat new in 1998. After doing some research on packing I came across this :

This is an ad from Western Pacific, the people that manufactured your teflon impregnated flax. I repacked the gland according to their instructions which really were nothing new but I was now satisfied it was done correctly. I followed their break in procedure and this is what I got :

Do We Really Need to Leak .............

............. yes, for good health, about four to five times a day is good. However, for a number of years I have been chiming in here on packing glands leaking and the fact I have run mine bone dry almost from the day I bought the boat new in late 1998 as a '99 model H310. As mentioned in...

forums.sailboatowners.com

I still do not allow my gland to leak and have a dry bilge. The gland face shows some moisture while under way but evaporates faster than it leaks.

I always get a chuckle out of the nay sayers who always retort, "But they always said it has to leak". Yes, before teflon impregnated flax came on the scene it did. Luddites and their moldy wet bilges . They can have it.

I would suggest you follow their break in procedure even if it means repacking the gland. I have no idea what happens to the packing if it is overly tightened from the get go. And when loosening or tightening when you're in the ZONE, I would recommend only turning 1/2 of a flat on the nut at any time.

 

[dkinzer]

Update: we motored for about 3.5 hours today at an engine speed of 2000 RPM (about 800 rpm on the shaft). The highest temperature I saw on the packing nut was 96*F early on and it settled down to about 85*F an hour in and stayed there. Interestingly, the shaft temperature was 10* lower than the packing nut, I presume due to heat conduction down the shaft and into the water. There is still no dripping - a good result, I think.

 

[Tally Ho]

Update: we motored for about 3.5 hours today at an engine speed of 2000 RPM (about 800 rpm on the shaft). The highest temperature I saw on the packing nut was 96*F early on and it settled down to about 85*F an hour in and stayed there. Interestingly, the shaft temperature was 10* lower than the packing nut, I presume due to heat conduction down the shaft and into the water. There is still no dripping - a good result, I think.

Sounds like you have it dialed in just right.

Greg

 

[Ralph Johnstone]

There is still no dripping - a good result, I think.

You're right. Another supporter of the "keep your bilge dry" followers. Don't let your gland drip.

 

[jssailem]

I ran my stuffing box for 7 years no drips. Temperature is the key issue. You are guarding against the stuffing flax burning up causing an uncontrollable leak and damaging the metal fitting or the shaft.

I have a fitting on the shaft log where I attached a hose and pump raw water into the shaft log to keep the air out, water flowing and the gear cool. No issues were observed even in reverse when cavitation can cause air to be trapped in the shaft log.

Give it time. Watch the temperature as you are. You have a good base point to guide you.

You can always loosen the stuffing box to induce water, but then Ralph may kick you out of his dry bilge guild.

I’m installing a dripless seal with the new shaft on this haul. Fingers are crossed that this will be an added feature not a nightmare.

 

[Ralph Johnstone]

You can always loosen the stuffing box to induce water, but then Ralph may kick you out of his dry bilge guild.

Anyone found to have wet sox will be immediately sacked .