Starboard pump sounds like gravel at idle

[MidnightRider]

Wondering if anyone has any experience with one of the pumps suddenly getting noisier. My starboard pump sounds gravely much like they sound out of water but now sounds like this when in the water at idle. It only does it under 1600 rpms or so, once over 1600 rpms it’s smooth as glass again. I haven’t lost any wot rpms and no cavitation. Outside of it just being noisier under 1600 rpms it’s business as usual. I can’t see anything of interest on the impeller either, looks fine. Not sure when it happened specifically but sometime this season. Any ideas? Just wondering if I should be worried about this or not. Thanks for any thoughts.

 

[Scottintexas]

I would normally think impeller cone bearing but being a 2017 that seems early to see a problem, it would be worth looking at though

 

[MidnightRider]

I would normally think impeller cone bearing but being a 2017 that seems early to see a problem, it would be worth looking at though

That was my first thought too but as you say, seems kinda early. You think it would only be making noise at idle? Like I said it is smooth as glass once you get past 1600 rpm. At first I even thought it was just a rough idle but it is clearly coming from the pump. One notch of no-wake button and it smooths right out.

 

[MidnightRider]

Just noticed I never followed up on this last summer. Thought I'd post in case someone had similar issue and came across this. Turns out a fresh set of spark plugs smoothed it right out. Sounded like the pump to me but did in fact end up being just a rough idle (only at idle rpm's) on one engine in need of new plugs.