2008 F150 lower unit rattle

[gct]

Running 3 blade 19P aluminum prop, no problem/no noise.

I go to a 3 blade 19P stainless steel prop (5200 RPM WOT with just me in boat), very slight noise/rattle in lower unit, at idle speed in forward or reverse. Not there in neutral, and bring RPMs up to 1000, no noise.

I just went to a 4 blade 16P, much better out of the hole with a full load, (still only 5600 RPM WOT with just me). But with this prop, I get a very loud rattle in lower unit at idle speed in forward/reverse, in the water, or in driveway running on hose. In neutral it's fine, in gear at idle it's there, as soon as I hit 900-1000 it levels right out and is quiet.

I also feel a very slight vibration at WOT.

Dealer says he's seen this on a lot of motors, (he sells Yamaha/Merc), mostly with heavier props. He says it's basically normal gear slop, but exaggerated due to the weight of the prop.

I have about 3 hours on this prop, maybe 10 on this lu lube change. I cracked the drain, saw nice clean lube, no metal on the plug/magnet.

Does this sound reasonable?

Thanks

[boats.net]

Prop chatter is common when using SS props, wont cause any damage but will make a noise in gear at idle and goes away when increase rpm's. Yamaha Reliance Series props works good on the F150 and helps to eliminate chatter.

[gct]

Thanks for the feedback, at least I know I'm not damaging anything. I do need to get it quieter though, this is annoying.