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Author Topic: Engine Shake  (Read 606 times)

June 07, 2009, 07:18:26 AM
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Plumbobber

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Engine Shake
« on: June 07, 2009, 07:18:26 AM »
Well, I managed to hit a rock with my prop while on vacation in the keys. I took the prop off and purchased an aluminum prop to get me through. Before I changed the prop I noticed some motor vibration. When I changed the prop, I noticed a little more vibration at idle and at slow speed. When I took it out of the water to flush the motor at idle it vibrates even more. I'm sure the shaft must be bent but why would the motor vibrate at idle in neutral?

June 07, 2009, 12:06:48 PM
Reply #1

GoneFission

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Re: Engine Shake
« Reply #1 on: June 07, 2009, 12:06:48 PM »
Bad news:  You might have bent the driveshaft (from the powerhead to the lower unit).   :x  
Good news:  Sometimes they can be straightened - find someone who does inboard shaft work.  You may not have to buy a new driveshaft.  

Also, could be you damaged a bearing in the lower unit.  You can check for a bent prop shaft if you have a dial indicator, but you can pretty much count on the lower unit coming off and some parts being replaced.  

Hope this helps - sorry you caught a prop shark.
Cap'n John
1980 22-2 CCP
Mercury 200 Optimax 
ASPA0345M80I
"Gone Fission"
ClassicAquasport Member #209


June 07, 2009, 01:03:15 PM
Reply #2

MarshMarlowe196

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Re: Engine Shake
« Reply #2 on: June 07, 2009, 01:03:15 PM »
When I hit the concrete boat ramp that came out of nowhere  :?  , I thought I had bent my driveshaft as well.  I was informed that if you have insurance on your boat, the damage caused by submerged object collisions is covered, less your deductible.  Might be worth looking into if you have insurance  :pl: .
Key West 1720 / Yam C90

Sold: 1973 Aquasport 19-6

June 07, 2009, 03:30:27 PM
Reply #3

Plumbobber

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Re: Engine Shake
« Reply #3 on: June 07, 2009, 03:30:27 PM »
Quote from: "GoneFission"
Bad news:  You might have bent the driveshaft (from the powerhead to the lower unit).   :x  
Good news:  Sometimes they can be straightened - find someone who does inboard shaft work.  You may not have to buy a new driveshaft.  

Also, could be you damaged a bearing in the lower unit.  You can check for a bent prop shaft if you have a dial indicator, but you can pretty much count on the lower unit coming off and some parts being replaced.  

Hope this helps - sorry you caught a prop shark.

Kind of what I was thinking but would the motor shake in neutral...if it were the driveshaft?

June 07, 2009, 03:31:32 PM
Reply #4

Plumbobber

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Re: Engine Shake
« Reply #4 on: June 07, 2009, 03:31:32 PM »
Quote from: "Badonquasport196"
When I hit the concrete boat ramp that came out of nowhere  :?  , I thought I had bent my driveshaft as well.  I was informed that if you have insurance on your boat, the damage caused by submerged object collisions is covered, less your deductible.  Might be worth looking into if you have insurance  :pl: .

What was the damage caused?

June 07, 2009, 04:00:47 PM
Reply #5

Plumbobber

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Re: Engine Shake
« Reply #5 on: June 07, 2009, 04:00:47 PM »
I just checked the prop shaft and it is bent. So, I'm guessing the driveshaft is also. :thumbdown: Anybody know a good shop in Naples,Fl.?

June 07, 2009, 06:42:03 PM
Reply #6

MarshMarlowe196

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Re: Engine Shake
« Reply #6 on: June 07, 2009, 06:42:03 PM »
Quote from: "Plumbobber"
Quote from: "Badonquasport196"
When I hit the concrete boat ramp that came out of nowhere :? , I thought I had bent my driveshaft as well. I was informed that if you have insurance on your boat, the damage caused by submerged object collisions is covered, less your deductible. Might be worth looking into if you have insurance :pl: .

What was the damage caused?

Luckily, nothing was internally damaged (best I can tell).  Just chewed up the prop real good, but it was the wrong pitch anyway.  :)
Key West 1720 / Yam C90

Sold: 1973 Aquasport 19-6

June 08, 2009, 10:48:53 AM
Reply #7

GoneFission

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Re: Engine Shake
« Reply #7 on: June 08, 2009, 10:48:53 AM »
The driveshaft is directly connected to the powerhead and turns anytime the engine is running.  The forward and reverse gears are in the lower unit, and the shifter rod moves them back and forth to engage the gears.  In neutral, the driveshaft is still turning, but neither gear is engaged.
Cap'n John
1980 22-2 CCP
Mercury 200 Optimax 
ASPA0345M80I
"Gone Fission"
ClassicAquasport Member #209


June 08, 2009, 12:31:29 PM
Reply #8

MarshMarlowe196

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Re: Engine Shake
« Reply #8 on: June 08, 2009, 12:31:29 PM »
Quote from: "GoneFission"
The driveshaft is directly connected to the powerhead and turns anytime the engine is running. The forward and reverse gears are in the lower unit, and the shifter rod moves them back and forth to engage the gears. In neutral, the driveshaft is still turning, but neither gear is engaged.

GoneFission is right, but just to add to this-  it is common to hear some noise while your engine is running but not engaged in forward or reverse.  The driveshaft kind of "floats" around while it spins and not engaged, sometimes making some noise that will worry you unless you know what it is.

Vibration is another story...
Key West 1720 / Yam C90

Sold: 1973 Aquasport 19-6

June 10, 2009, 04:34:46 PM
Reply #9

Plumbobber

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Re: Engine Shake
« Reply #9 on: June 10, 2009, 04:34:46 PM »
Mechanic got her all apart and it's just the prop shaft. :cheers:  I was sweating it out!

June 10, 2009, 07:21:25 PM
Reply #10

RickK

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Re: Engine Shake
« Reply #10 on: June 10, 2009, 07:21:25 PM »
8)
Hope you marked that rock on your GPS  :wink:
Rick
1971 "170" with 115 Johnson (It's usable but not 100% finished)

1992 230 Explorer with 250 Yamaha

 


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