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Author Topic: Anyone Heard This Before?  (Read 3004 times)

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rab1090

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Anyone Heard This Before?
« on: July 08, 2001, 10:37:40 PM »

I was motoring along at about 1800 RPM last week, when I heard a "clicking" sound coming from beneath the transom.  It sounded like a harmonic vibration, in tune with the prop shaft.  Within less than a minute, it became louder and then it suddenly sounded like the shaft was tearing a new hole in the Cutless bearing.  Kind of sounded like a diesel truck downshifting, as I suppose the noise was being transmitted up through the hull via the strut.
 I had a diver take a look at the prop, strut, bearing and shaft.  He reported all appeared normal.  I then had the local shop take the boat out for a sea trial and they reported that they couldn't find anything wrong.  They checked the engine alignment, shaft, PSS seal and generally anything that might have caused the noise.  They found nothing.
 This evening, I ran the engine at about 1800 RPM while returning to port.  The same "ticking" sound began, growing louder, followed within less than a minute by the same loud "screeching" sound.
 We run an over-pitched 3-bladed 15x11 (I'm going to have it re-pitched to 10" soon) on a bronze 1" shaft, with 2 new zincs and a PSS Shaft Seal (installed last September).  Last September, when the boat was hauled, the Cutless bearing showed no wear.  We've put 45 hours on the engine since then.
 Does anyone have any ideas as to what might be causing this noise?  I have plans to leave for a three week sailing trip soon - and in the absence of any other suggestions, I'll have to have the boat hauled, the prop re-pitched and a new stainless shaft, line-cutter and Cutless bearing installed.
 I'd rather hear that it's something cheap and simple :confused
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mitch brown

  • Guest
Unexplainable?!?
« Reply #1 on: July 09, 2001, 09:04:36 AM »

Bob-
 
   I seem to remember some time ago (possibly a couple of years) that I had a noise like the one you described. It happened intermittently, then one day the screeching became very loud and the  eng. temperature shot up. Have you had the engine compartment open while you hear the noise? Is the noise definately coming from the shaft/seal/strut area? Good luck.
 
 Sea Vu Play
 #282 Long Beach CA
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mitch brown

  • Guest
Unexplained continued
« Reply #2 on: July 09, 2001, 09:09:49 AM »

I forgot to mention that the noise was being caused by  the water pump slowly seizing up. I had to replace it, which wasn't a big deal.
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Fulvio

  • Guest
similar problem
« Reply #3 on: July 09, 2001, 11:46:03 AM »

Last Sunday I started hearing a similar sound.  I would describe it as "chirping", and it was in rythm with the engine.  I tried everything I could to figure out where it was coming from:  opened lazarette and stuck my head down below, opened engine compartment, crawled under mattress in aft cabin and opened bearing cover.  Everything looked and sounded perfectly normal.  The only way to hear an increase in the noise was to hang outside over the side stern pulpit or lifelines.  Not over the transom, only over the side, either one.  
 Then I found that by reducing the engine speed it would stop altogether (I was running at between 2500 and 3000 RPM).
 I did not like that sound at all, but I still don't have any idea what it could have been.  I'll ask a diver to check out the prop and strut.
 I'll let you know what gives.
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jentine

  • Guest
Anyone Heard This Before?
« Reply #4 on: July 10, 2001, 04:10:14 AM »

Several years ago, I had the cutlass bearing replaced and when I used the boat for the first time, there was a loud squeal coming from the shaft, "somewhere".  I immediately called the mechanic and told him that he left a pig in my boat and described the problem.  I learned that the squeal was not coming from the bearing, but from the new three bladed 15X11 prop that I had installed.
 I ultimately returned the prop to the shop where I bought it and they knurled the leading edge of each blade.  The squeal ceased.  I hope this is your problem.
 It sounds like you may have something else going on, because of the pre-squeal sounds that you are experiencing.  Jim Kane
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Jim Rose

  • Guest
Shaft Noise
« Reply #5 on: July 10, 2001, 04:11:40 AM »

Same noise happened to me last weekend.  Running along at 2000 RPM and loud noise from shaft area.  Thought I wraped up something in the prop.  Reduced speed to idle, then reverse.  Noise went away.  Later inspection revealed the PSS shaft seal must have went dry.  Lots of carbon deposits.  I readjusted PSS shaft seal, burped it and cleaned up the carbon deposits.  Motored her for a couple of hours and everything seems fine.  My boat only has 30 Hrs. on her.  My friend also has a 2000 Model and the same thing has happened to him.  Dripless shaft seal running dry.
 There are four allen set screws on seal the two primary lock it to the shaft, and the second two lock the primary from backing out.  If this problem continues, I will go back to the original packing.
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rab1090

  • Guest
I found the Source of the noise!
« Reply #6 on: July 10, 2001, 07:39:00 AM »

Thank you for all of your suggestions!  Armed with this feedback, I returned to the boat and soon determined that the sound was in fact coming from the PSS bellows, as it slapped against the shaft.  It had come loose and the black disk at the end of the bellows would begin a harmonic motion, as the spring tension was VERY light.  Luckily, the safety hose-clamp held and no water came through.  I was surprised that the mechanic who checked the PSS seal hadn't noticed that the disk on the shaft had slipped (but then again, I hadn't noticed, either).  Thanks again, to all.  What a great group (gaggle?) of boaters
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SOJourney

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Noise
« Reply #7 on: July 12, 2001, 09:00:56 AM »

I had a similiar thing happen to me two years ago.
 I thought the transmission was going out. I wound up rebuilding the transmission and putting in a new cutlass bearing. I believe the problem was the cutlass bearing because the folks that rebuilt the transmission said it wasn't in too bad of shape.
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Roc

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Chirp..Chirp
« Reply #8 on: July 12, 2001, 01:53:57 PM »

I have a chirp on my boat and I know what it is from.  It's the ignition buzzer.  Apparently, when a certain rpm is reached (i.e. harmonic vibration throughout the boat), I can hear the buzzer chirp.  The dealer changed the ignition and the buzzer but that did no good, the chirp is still there.  One of these days I plan to look at the wiring.  Maybe something is making contact to activate the buzzer ever so slightly.
 
 Roc-
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Roc - "Sea Life" 2000 MKII #1477.  Rock Hall, MD
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