3.0 OMC lower end knock at idle

[89cruisers]

My OMC 3.0 with less than 400 hours in my bayliner has a noticeable knocking from what seems to be the lower end at idle, noise either goes away when adding throttle or is just masked by the rest of the engine noise, it would seem this would be bad rod bearings, but with not even 400 hours, any ideas before I get this engine out, no other engine issues before hand, and oil changed every season (30-40 hours)

 

[89cruisers]

Re: 3.0 OMC lower end knock at idle

Is it possible that this is piston slap since it is only at idle, but it doesn't go away when warm though