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AlphaOne Gen II Vibration Rumble

integra

New member
"Doral Prestancia 270MC runnin

"Doral Prestancia 270MC running twin 4.3L LX engines and Alpha One Gen II (port is counter rotating) sterndrives.

I have a vibration / rumble in the starboard drive. At 1500-1600 RPM it is most noticeable and then calms down a bit around 2000 RPM. At 3200-3400 RPM it is more like a rolling rumble.

I am wondering if I have a bad gear set, or worn bearings in the drive or if I might have a bent shaft. The drives only have about 250 Hours on them since they were completely rebuilt. The vibration became noticeable about 25hrs runtime ago.

I am prepared to replace the entire starboard drive with a brand new unit, but would hate to be wasting my money on this.

Any help or suggestions would be appreciated."
 
"Have it checked out first. It

"Have it checked out first. It may be your gimble bearing or universal joint shaft from eng coupling thru gimbal bearing to outdrive unit. Get second opinions! Marine mechanics have been known to get greedy as the season begins to slow down towards the off season. Dont rush to replace anything til you are certain of whats causing that rumble. Trust me,get a second or third opinion!"
 
This boat only has 525 hours o

This boat only has 525 hours on it. Could the engine mounts be loose with such few hours on it? It is easy to check and I will but I think my issues are deeper inside.
 
Check the prop on that side. I

Check the prop on that side. I had a vibration and I thought it was in the motor then the drive. Turned out to be a very slightly bent blade.
 
I'm with Baytro. Swap out

I'm with Baytro. Swap out the prop with a borrowed one and see if it goes away. If it does problem solved at no cost.
 
Thank you for your advice. I

Thank you for your advice. I am running Stainless Steel props on the boat and am wondering if in fact they can be bent causing the vibration.

I don't have a spare to try out but could remove the prop and take it to my local prop repair guy to have it examined.
 
"When a prop is bent one of th

"When a prop is bent one of the blades does not stick as far back as the others. You can use a ruler or something similar. Clamp it against the lower unit and align it with a tip. Now rotate the prop to the next tip, then the next. I straightened my blade using this method and checked the blades at differant distances from the hub. You will not be able to straighten your ss prop but hopefully will be able to tell if it's bent."
 
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