Stuffing Box Issues

[tlkenyon]

Yesterday, I had a mechanic replace the impeller, and while he was on the boat (2015 25sc) check and then replace the shaft packing. We are in Orillia, Ontario in the Mideast of doing the Great Loop and now have just short of 1,000 hours on the boat. Original impeller and shaft packing. Have previously adjusted the packing several time and thought it might be time for replacement.

Underway after the work, I shot the packing nut with my laser thermometer and saw 120F, when at 1600 rpm. After ramping up to WOT (2850 loaded like we are), measured 140F which shortly climbed to 165F. Backed down and made it to a marina. Was seeing 1-2 drips every 5 seconds or so.

Next morning, after she cooled off, backed the packing nut off about one-quarter turn (about 2 flats on the nut). When retightening the Lock nut, it pushed the packing nut off the end of the shaft log. Try as I might, I could not get the packing nut to engage the threads on the shaft log. Needless to say, water was coming in....but bilge pump is keeping up.

I think the mech put in too many rounds of packing or did not get all the old packing out. It came out in pieces, so was hard to tell.

Waiting right now for him ( who shall remain nameless for now) to return to the boat to remedy the situation.

Anybody got any wisdom for me?

Will update later.

TK

 

[captstu]

While you are waiting, very lightly tap the packing in several places pushing it back into the shaft log. Over packing is a frequent problem - but pulling it out and putting in new is nail biting if you have never done it before --- very easy the second time.

While you are having him replace the packing - be sure to taper the cuts so the packing overlaps the joint. Two inclined planes, one on each end about 1/4" to 3/8" long to minimize the overlap.

Have her/him check the hose clamps Two of mine failed! causing water to come in around the shaft log. Fortunately, I caught the failure on inspection and replace the Hose clamps with no problem. The Hose clamps on my R25 sit with the bottom portion in the water that is below the ability of the bilge pump to remove - thus the near disaster waiting to happen

Good luck!

 

[tlkenyon]

Captstu....thanks for the input. He should be here shortly.....

TK

 

[knotflying]

Hopefully it works out for you. Three pieces of packing are what is required and as Capstu said a bias cut on each piece end. The joints should be staggered like 1 6 and 10 o'clock. A great trick, showed to me by Gansett Ranger, is to have a 1-1/4 inch piece of PVC pipe about an I-1/2"" long cut, in half. When you insert the first piece insert the PVC behind it and squeeze it in using large channel locks, one end on the end of the PVC and the other on the back of the packing nut. When all three are in then hand tighten the nut until the water stops running out and leave it alone.
You will find on initial installation the temperatures will be high and you may get more water splashing in then usual. The packing has to wear in. After a few hours of run time you should see the temperatures reducing and then adjust the packing nut accordingly. A very slight turn each time is all that is required, like only a few degrees.

 

[captstu]

I didn't know about the 3 pieces of packing. Thank you.!

When I change packing - 3 piece staggered as suggested - I hand tighten the nut until the water runs slowly, but freely - a constant drip every 2 seconds is about right. Be sure and fully snug the backing nut.

Then I run the boat for an hour or so and retighten the nut to about 1 drip every 30 seconds, fully snugging the backing nut again.

I mark the backing nut place on the log about 1/4" in from the 1 drip every 30 seconds. When the nut is retightened to the point where the mark is covered, it is time to change the packing.

I always change the packing when the boat is out of the water for several months after it has been in place for several months, my theory is the lubricant on the packing dries out over time.

I eventually tired of keeping the boat afloat this way and put in a dripless seal. No more checking, no more adjusting. Seems a good idea after 2 years or so.

If it is a new purchase option, I suggest the extra $200 for a dripless seal is worth it - no more adjusting for years and years of usage.

 

[Wildcats]

I have a question about checking your packing gland. From Andrew Custis' fine video about adjusting the packing nut, he suggested that there be a drop 3/ minute. Should this be checked 1) at rest without engine running 2) engine running but at rest 3) engine running and boat in gear with shaft turning?

 

[Dale777]

I have a question about checking your packing gland. From Andrew Custis' fine video about adjusting the packing nut, he suggested that there be a drop 3/ minute. Should this be checked 1) at rest without engine running 2) engine running but at rest 3) engine running and boat in gear with shaft turning?

Number (3) is correct.

 

[tlkenyon]

Update. Mech arrived Saturday morning. Confirmed that the packing nut was too full to allow engagement of the threads on the stern tube. Removed three rounds of packing, somewhat burnt,but not too bad. Confirmed that the packing nut was indeed empty. Reinstalled two rounds of packing. Packing nut threads onto the stern tube with about 3/4 of an inch remaining for adjustment. Another round of packing would not have fit. Must be something about (abooot) Canadian packing.

Went for a spin, no heating, enough dripping. Left me with some packing to add when needed. Will keep an eye on it.

Onward to Georgian Bay!

TK

 

[knotflying]

You might be okay. The size of the packing should be 1/4 inch. Putting in three pieces without compressing each piece before adding the next will create your situation. Did the mechanic mark where the joints were? Hopefully he did so that if and when you have to add the third piece you can stagger the joint.