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Old 08-14-2019, 10:03 PM   #1
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City: Rock Island, IL
Country: USA
Join Date: May 2013
Posts: 68
Excessive Vibration MS Pilot 34

Our 2007 MS Pilot 34 suddenly developed a lot of vibration above 2000 RPM and got worse at 3000 RPM where the whole boat is vibrating. Took it to t h e marina where they hauled it and checked the running gear. Could not find excessive play in the cutlass bearing, the engine and trans seems to be okay, took off the swim ladder, and prop shaft line cutter and still vibrates. It seems to be downhill of the shaft log. They want to take the prop in but we never hit anything and it was checked and found to be in spec when we bought the boat. Will have the marina replace the cutlass bearing tomorrow. They are going thru the process of elimination. What type of shaft log do we have? 2 pieces? Any o n e have any ideas? Thanks for any recommendations!!

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Old 08-15-2019, 06:49 AM   #2
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City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23
Join Date: Aug 2012
Posts: 4,638
The Pilot 34 has a well known and discussed (on this forum) problem with prop cavitation or similar cause. On my boat it slowly increases after a bottom cleaning and is back to normal after a good cleaning.

So the first thing to ask is do you do routine bottom cleanings and did this problem occur after the boat sat for a month or two in the water (salt of course) where fouling could have bloomed suddenly.

If this is not the case then look at the common causes of prop vibration:

0. Run the engine up in neutral. Does the engine shake. Could be torsion damper is failing.

1. Tighten the coupler bolts, then put a dial indicator on your prop shaft (inside the boat) and look for run out. Should be less than .005".

2. With the boat hanging in the Travellift slings, hold a pointer at the tip of the prop and turn it. You should see very little, ie 1/16" or less variation.

3. Check to see that the prop nuts are tight, although #2 is a pretty good indication that they are and that the prop is seated on its taper.

4. Put a dial indicator where the zinc goes on the prop shaft and check for runout there.

5. Finally if all of the above checks out, pull the prop and send it to a prop shop for truing.


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Old 08-15-2019, 09:39 AM   #3
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City: Upstate,SC
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Vessel Name: Caroliner
Vessel Model: 28' Spira San Miguel
Join Date: May 2012
Posts: 2,226
Also, check the condition of the engine mounts. They could be the cause even if they look ok. Engine to shaft alignment causes some weird vibrations that seem to come from nowhere. Do an engine alignment in the water.
What a pain in the transom.

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