Just replaced my stuffing box with a PYI dripless. I now have vibration over 1500 RPM which I NEVER had before. Engine is as close to perfectly aligned as possible (.002 feeler tolerance) as is cutlass to shaft. My mounts are three years young and I had nothing like this before the change. No prop change, no shaft damage, no other changes. I did worry about the removal of a 'bearing' (the old stuffing box) in the system allowing more movement. Is this what is happening?! Very discouraged!! Jeff Jones S/V Escapade
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Did you do other work too?
Like replace the cutlass? What I'm getting at is that the problem likely resides elsewhere. The stuffing box provides no real supportive bearing. Shafts get bent very easily, for example. I can imagine your disappointment, especially after a careful installation. It might be worth checking the alignment again if its possible it was done before the boat settled. Good luck. Rick D.
Like replace the cutlass? What I'm getting at is that the problem likely resides elsewhere. The stuffing box provides no real supportive bearing. Shafts get bent very easily, for example. I can imagine your disappointment, especially after a careful installation. It might be worth checking the alignment again if its possible it was done before the boat settled. Good luck. Rick D.
Shaft Seal Can't be Problem
I agree with Rick, the PSS shaft seal can't be the problem - there has to be something else.
I agree with Rick, the PSS shaft seal can't be the problem - there has to be something else.
Agree with John
I had a PYI PSS installed on a 40.5 but the guy I had do it did not remove and reinstall the shaft coupling properly causing vibration. When I had the coupling replaced later by a yard - no vibration. The shaft seal, not matter what type, should never act as a bearing (support) for the shaft. If it did, it would cause vibration since it would have no means of alignment. Check the shaft coupling connection. If it is OK then you should check the shaft and cutlass bearing again. Your post said you know they and the engine are properly aligned but check them and those engine mounts again to see if they are right and tight. My vibration caused the mounting nuts to get loose. My PYI PSS had performed flawlessly over the last 2 years with a LOT of motoring in the ICW while cruising from Texas to the Chesapeake and back again.
I had a PYI PSS installed on a 40.5 but the guy I had do it did not remove and reinstall the shaft coupling properly causing vibration. When I had the coupling replaced later by a yard - no vibration. The shaft seal, not matter what type, should never act as a bearing (support) for the shaft. If it did, it would cause vibration since it would have no means of alignment. Check the shaft coupling connection. If it is OK then you should check the shaft and cutlass bearing again. Your post said you know they and the engine are properly aligned but check them and those engine mounts again to see if they are right and tight. My vibration caused the mounting nuts to get loose. My PYI PSS had performed flawlessly over the last 2 years with a LOT of motoring in the ICW while cruising from Texas to the Chesapeake and back again.
Verified those items
I re-aligned after three weeks in the water and re-checked this last weekend. All OK. No rig adjustment during that time either. Engine mounts are tight and no other work was performed. Engine runs very smoothly with no load and no smoke either loaded or unloaded, i.e.: no suspected engine induced vibration in excess of normal. Cutlass had been replaced at the beginning of last season so it remains untouched (and in good shape). Prop shaft never came out of boat, just slipped aft enough to R&R seal. I'm very stumped! Jeff
I re-aligned after three weeks in the water and re-checked this last weekend. All OK. No rig adjustment during that time either. Engine mounts are tight and no other work was performed. Engine runs very smoothly with no load and no smoke either loaded or unloaded, i.e.: no suspected engine induced vibration in excess of normal. Cutlass had been replaced at the beginning of last season so it remains untouched (and in good shape). Prop shaft never came out of boat, just slipped aft enough to R&R seal. I'm very stumped! Jeff
Vibration Resolved
The vibration issue is now resolved. I loosened the coupler once again to check alignment. Everything checked out OK, less than .002 all the way around... then I thought, perhaps I should rotate the shaft 90 degree's and re-check. It so happened that the shaft was aligned well with my reference mark at the top (blades straight up and down) but not at other rotational angles. Faced with possibly having to haul the boat I loosened the set screws from coupler to shaft and dove below to give the shaft a couple of good hits, trying to ensure the shaft was fully driven into the coupler hub. Having marked the shaft, I saw that I gained about 1/16 of an inch or more after several blows. Now I had to re-align again, but found that at 3, 6, 9 and 12 O'clock the gap remained constant. Bolted down, sea-trail, and all OK. Whew! The only thing that concerned me was impacting the transmission bearing with the way I drove the shaft into the hub. Ideally I should have driven the hub onto the shaft from inside the boat with a solid object backing up the shaft, but that would have been difficult in the water with one person. Jeff Jones S/V Escapade
The vibration issue is now resolved. I loosened the coupler once again to check alignment. Everything checked out OK, less than .002 all the way around... then I thought, perhaps I should rotate the shaft 90 degree's and re-check. It so happened that the shaft was aligned well with my reference mark at the top (blades straight up and down) but not at other rotational angles. Faced with possibly having to haul the boat I loosened the set screws from coupler to shaft and dove below to give the shaft a couple of good hits, trying to ensure the shaft was fully driven into the coupler hub. Having marked the shaft, I saw that I gained about 1/16 of an inch or more after several blows. Now I had to re-align again, but found that at 3, 6, 9 and 12 O'clock the gap remained constant. Bolted down, sea-trail, and all OK. Whew! The only thing that concerned me was impacting the transmission bearing with the way I drove the shaft into the hub. Ideally I should have driven the hub onto the shaft from inside the boat with a solid object backing up the shaft, but that would have been difficult in the water with one person. Jeff Jones S/V Escapade
Not the seal
Dear Jeff, I’m glad that you have figured your problem out with the alignment and that it was not the seal. If a stuffing box is supporting a shaft it should not. This will place undo pressure on the stern tube, which for the most part is not designed to handle. Take care Kevin
Dear Jeff, I’m glad that you have figured your problem out with the alignment and that it was not the seal. If a stuffing box is supporting a shaft it should not. This will place undo pressure on the stern tube, which for the most part is not designed to handle. Take care Kevin
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