2006 SX-A, grumble around 2k-2.5k RPM

[void7910]

And I am back. Had the boat out on the weekend and it appears (what I assume is the outdrive) has developed a grumble around 2000-2500 RPM. At lower RPMs it is quiet once I get on plain around 2800-3000 RPM it sounds fine. It's _just_ in the 2000-2500 RPM range.

I was thinking maybe u joints but I would assume they would be loud at any RPM. It doesn't seem to be worsse when the drive is turned, likewise it still makes the noise when perfectly straight so I think that rules out gimbal.

Any thoughts on what could be the issue?



Thanks in advance all!

 

[bruceb58]

You check alignment annually when you take the drive off?

 

[void7910]

I think alignment was checked last fall when I had it serviced. I can check the receipt though.

 

[void7910]

Checked the receipt and it doesn't mention pulling the outdrive or anything about alignment, so I guess the alignment was not checked.

 

[void7910]

Update. Had some time today to get it started in the drive. Ran it up to 3000 RPM in neutral with the prop off, drive left/right, up/down, no noise. Same in forward. Same in reverse. The two possibilities I see are

1) The issue is only prevalent when there is pressure on the drive in the water, spinning a prop.

2) It was our first run with this re-manufactured prop that came with the boat. Perhaps the prop geometry is not quite right and it starts to cavitate/vibrate/other at a certain speed/rpm. I've put our old prop on (with a slightly bent fin tip) to see if the issue magically goes away next outing.