Lower end question

[JJB]

I have a 175 that when I run at low rpms I hear a low grumbling Noise and vibrations from 1000rpms to about 1500 rps then goes away . I have great hole shot and great top end speed with it with no odd noises . but when I return back down to 1000 to 1500 I get the vibs and grumbling noise . The engine sound great at those rpms in neutral with no vibs or grumbing noise . any ideas what it may be ? I am running a 4 blade ss prop 18 pitch and get about 5200 wot . Thanks for the input !

 

[Dhadley]

Re: Lower end question

Which 175 do you have? (Regardless, you're lugging it at 5200)

 

[JJB]

Re: Lower end question

Thanks Dhadly , I have a 2000 175 vxsss 25" shaft. what do you think the noise is coming from and what prop would you suggest me to use ?