{Stus-List} Engine / Prop Shaft Alignment, Stuffing Box

Jim Watts jimwatts at shaw.ca
Wed Jun 4 10:24:40 EDT 2008


Here's the full horror story:
When I replaced the cutless bearing, I noticed it was worn off-center. When we relaunched with the new-to-us Max Prop, the vibration was severe. The culprits were:
bent shaft
coupling out of alignment
strut out of alignment

We got a new coupling, shaft, and PSS dripless shaft seal, realigned the strut, and had the engine realigned. Fixed most of the vibration, but this year I think I'll get the Max Prop rebalanced to remove the residual vibration. It could be any of those things, or all of them as it was for us. 
It was kinda spendy (hack choke)...

Jim Watts
Paradigm Shift
C&C 35 Mk III
  ----- Original Message ----- 
  From: Nauset Beach 
  To: cnc-list at cnc-list.com 
  Sent: Wednesday, June 04, 2008 4:49 AM
  Subject: {Stus-List} Engine / Prop Shaft Alignment, Stuffing Box


  Once again I come back to the well of knowledge:

  Problem # 1: vibration when in gear.  

  History:  
  March, 2006:  replaced engine mounts with same OEM mounts [Yanmar],  aligned engine / shaft
  2006 season:  little vibration during use, though more than prior season
  2007 season:  Vibration worsens - am guessing due to compression of new mounts
  April, 2008:  replace 3 yo cutless bearing, installed gore-tex packing in stuffing box [Problem #2 below]
  vibration slightly less but intolerable, and probably damaging to something

  Prop: geared, folding Flex-o-Fold.  cleaned and greased April, 2008.

  Checked alignment last night: slight gap at bottom of coupling faces
  Lowered front two mounts - gap closed.  3/1000" feeler guage is close to equally tight all round coupling.

  Port forward mount is closer to the top of the threads on the post than the other 3.  Raised question:  Is this creating "torque" on the engine itself with unequal amounts of weight on each mount?  How does one "equalize" the percentage of weight on the four mounts?  Could this be causing the vibration?  Any suggestions as to what else to check?  Stainless shaft is slightly scored presumably due to delay in packing replacement 8 years ago. 

  Problem # 2:  no water through stuffing box.

  April, 2008: Replaced PTFE packing with the Gore-tex packing - boat was on the hard.
  Tightened stuffing box - possibly overtightened - as was not on board at launch and did not want water leaking in prior to my return.
  After launch, loosened stuffing box and cannot get water through the packing.  Water does run along the threads of the stuffing box when I loosen the packing nut but not out along the shaft. When the nut is tightened to stop the flow out the threads, the shaft gets hot.

  Conclusion:  Am guessing I need to replace the packing again as it probably was packed too tightly in the packing nut and is now preventing water to flow.  With the boat in the water, was hoping to avoid that adventure.  Thoughts?

  Any suggestions on either situation are appreciated.

  Thanks,
  Brian


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