Stuffing Box Hell

Alan Gomes

Sustaining Member
I suspect I have to losen the stuffing box a bit. I did a 10 minute run from the yard where I worked on her to the new home port and as far as I could tell not one drip! I am using regular flax packing, so I suspect I have to have some drips happening while turning the screw.

I am open to hearing suggestions.
Yes, it should drip or at least weep water some. All forms of packing have to.

If you have someone else along who can steer, you might want to feel the packing nut to see how warm it gets.
 

tenders

Innocent Bystander
I'm using an infrared thermometer "gun" ($20 at Harbor Freight) to assess the tightness of the packing gland - the part that contains the packing, not the shaft or hose. At the moment, it's dripping slightly at rest, and a bit more in motion, but the temperature rises to 170 degrees during a 15-minute run at cruising speed to the starting line of our racecourse. This isn't hot enough to damage anything for a short period of time but it seems too hot to be the correct long-term setting. I'm going to loosen the nut by a flat or two, just a few degrees, to see how sensitive the temperature is to the nut position.

I was a little surprised the part gets that hot considering that through the threads, it does have thermal connectivity to the inner piece that is presumably water-cooled to 75 degrees or so.
 

wynkoop

Member III
Tenders thanks so much for that metric. I am going to grab a Harbor Freight temp gun and do a test this weekend. I did no stuffing box work today. It was a pleasant change to be bedding deck hardware with a gentle breeze!
 

1911tex

Member III
From what I gather from this very important thread....the number of drips is totally irrelevant; whether under load or at rest. It is the temperature of the packing nut under load that counts; the-at rest drip is totally dependent on the load temp. What is the most ideal temp for this nut under a work load in your opinion? What is the maximum temp that is not to be exceeded?? Thanks!
 
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wynkoop

Member III
For others following the stuffing box saga I just stumbled across this article that I think is of use.

 

Alan Gomes

Sustaining Member
I'm copying below an e-mail exchange I had with Steve Gaston from Buck Algonquin tech support. This addresses some of the questions that have been raised in this thread.
Alan

E-mail below:

On Behalf Of Steve Gaston

Sent: Saturday, May 08, 2010 9:57 AM
To: Alan Gomes
Subject: Re: Packing box issues

Dear Alan,

We have seen the variations in the packing sizes that you have described. 95% of my packing box questions revolve around the goretex graphite based packing. It is good packing. However, most people misinterpret the instructions and believe it is drip free. All three material (graphite, Teflon, and flax) have their drawbacks.

Flax. low cost. temperature tolerance minimum. abrasive. Does require water for cooling and lubrication.

Teflon. medium cost. High temperature tolerance (packing only). mildly abrasive. Does require water for cooling and lubrication.

Graphite. higher cost. High temperature tolerance. least abrasive. Does require water for cooling and lubrication.

The common theme here is they all require water for cooling. I do not believe you will get a much better setup than the goretex running at the 130 degrees. The temperature will vary with the amount of water drip through the packing and the shaft speed.

The other components have a reasonably high tolerance to heat. The packing box hose is made of the same materials as marine exhaust hose. The bronze and stainless are not a relative heat consideration.

The abrasion factor would be the other consideration. Since the goretex has the least abrasion impact, it would be the better choice.

I hope this helps.

Best Regards.

Steve
 

Alan Gomes

Sustaining Member
One other tip: I think a temp of 170 degrees was mentioned in an earlier post. That seems much too high. One thing to check is whether you are seeing any drips with it running in gear and--this part is crucial--confirm that the drips are coming from where the shaft exits the stuffing box. What can happen is that the packing is jammed tight in the nut and there are no drips. Then, a person will loosen the nut until he/she sees some drips. But when you loosen the packing nut enough, you can get drips coming out of the back side of the nut, which will do nothing to cool the shaft. Because of the slope of the shaft, the drips will run downhill and drip toward the aft end of the stuffing box hose, just the same as if the drips were coming out of the front of the packing box (if that makes sense). So you need to look not just for dripping, but make sure that the interface between the shaft and the packing nut, where the shaft exits the nut, shows moisture coming out of it. Even if it's not actually dripping, you should see some glistening of moisture right at that point to let you know it is getting cooling water. If you see that, this means water is cooling the shaft and the temps should reflect that accordingly.

A perfect setting would be a very slight weeping of water when the shaft is rotating and no dripping after the boat has sat for a while and is at rest. (The dripping will not stop immediately after shutting down the engine.) If you have to err, let it drip a bit vs. too tight.
 

1911tex

Member III
Alan: Thick petrified skull here...when you mention "confirm that the drips are coming from there the shaft exits the stuffing box"....Is that the engine side of the stuffing box or the threaded locknut side of the box ? I am assuming? you reference the engine side. The referenced "back side" is the locknut side?
One other tip: I think a temp of 170 degrees was mentioned in an earlier post. That seems much too high. One thing to check is whether you are seeing any drips with it running in gear and--this part is crucial--confirm that the drips are coming from where the shaft exits the stuffing box. What can happen is that the packing is jammed tight in the nut and there are no drips. Then, a person will loosen the nut until he/she sees some drips. But when you loosen the packing nut enough, you can get drips coming out of the back side of the nut, which will do nothing to cool the shaft. Because of the slope of the shaft, the drips will run downhill and drip toward the aft end of the stuffing box hose, just the same as if the drips were coming out of the front of the packing box (if that makes sense). So you need to look not just for dripping, but make sure that the interface between the shaft and the packing nut, where the shaft exits the nut, shows moisture coming out of it. Even if it's not actually dripping, you should see some glistening of moisture right at that point to let you know it is getting cooling water. If you see that, this means water is cooling the shaft and the temps should reflect that accordingly.

A perfect setting would be a very slight weeping of water when the shaft is rotating and no dripping after the boat has sat for a while and is at rest. (The dripping will not stop immediately after shutting down the engine.) If you have to err, let it drip a bit vs. too tight.
I apologize for requesting the clarification...
 

wynkoop

Member III
Yeah considering I had ZERO water after a 10 minute run I have to loosen the packing nut this weekend and do a static test at the dock pulling against my dock lines.
 

Alan Gomes

Sustaining Member
Alan: Thick petrified skull here...when you mention "confirm that the drips are coming from there the shaft exits the stuffing box"....Is that the engine side of the stuffing box or the threaded locknut side of the box ? I am assuming? you reference the engine side. The referenced "back side" is the locknut side?
I apologize for requesting the clarification...
Sorry if I was unclear. But yes, this would be toward the engine side. I'm talking about the exact place where the shaft exits the packing nut on its way to the transmission coupler/transmission/engine. That's where all the friction is going to be and that's where you need to see some moisture.

My point was that you CAN get water coming out the AFT end of the stufing box and so it can appear to be dripping just fine. But that water just means you have loosened the heck out of the packing box nut and water is seeping through the threads and dripping. That does nothing to cool the shaft where it needs it: at the point the shaft exits the packing nut on its way to the coupler/transmission.

Hope I did better this time! :)
 

wynkoop

Member III
Sea Trials underway

Over the past couple of days I moved the temp probe for my digital thermometer that I had on the external portion of the fresh water loop to the stuffing box to read it's temp.

I made a couple of runs, that were probably further than I should have to check the temp. After the first one the temp was marginally within spec according to one article I read on the web. I did that run at 80% throttle....No Tach yet. Since it was marginal I backed the nut off a quarter turn and did another run yesterday, but after running at 80% for about 45 min with steady temp still marginally within range I ran up to full power for 15 minutes and noted that at first it cooled down a couple of degrees, then went up to out of spec.

I will next just back the thing off until it drips at rest then tighten until no drip and take another run down the bay under power.

Family obligations may get in the way of this, so expect an update when you see it.
 
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