Weird Motor Noise At High Rpm?
 

I've been having a noise coming from where I believe is the lower unit at 3500k and above and when I'm turning the boat the noise goes away but when I'm heading straight It comes back

Any ideas?

Thanks Tyler

Drain and inspect your lower unit oil...micro partials are acceptable on the plug, anything other than that is trouble. Check hub on propeller additionally.

Verify there is no excessive prop shaft play. Grab the prop and pull/push and see if the prop shaft moves in or out. What is the nature of the noise? Tapping sound?

I had one develope a high pitch sound. It was a pinion bearing

It does move a little like a half inch or so

That's definitely on my to do list b4 I take the boat out again

thanks
Tyler

The prop shaft moves back and forth a 1/2"? That's way to much freeplay. Does it clunk when shifting into gear or do you have to use any force to get it in forward or reverse?

It's the prop that moves slightly back and forth and it shifts in and out of gear fine no clunking

The prop is attached to the prop shaft. Assuming the prop nut is tight, any movement front to back is prop shaft play.

Possible spun hub, swap props with buddy and give it a go.

Spun hubs whirl and produce strange vibrations; additionally the rpm will jump around when torque increases with higher RPM's as the propeller and hub are no longer in synchronization. Top speed will be lacking, this phenomena only occurs at full torque/RPM. Side loading/turning increases the lateral force on the prop/hub and often lessens the slip, thus sound-vibrato is absent. The durometer of the rubber hubs, in time will break down, especially if the prop has struck an object known or otherwise.

What prop-pitch/hub-design/engine-manufacturer is in question so someone may lend you a prop for a test run if you don't have a spare?

In any situation, a full inspection is in order, if you have shaft play proper further inspection is required. It is not unusual to pick up foreign material(fishing line, rope, etc) and it wrap on the output shaft. If you pull the lower unit make sure to replace the water pump with a comprehensive new kit not just the impeller...a new housing is often necessary.

Naw... a 1/2 " end play is bad. Time to rebuild lower unit.
It's not a bad thing as you can get decent parts in our area.

Any news on the issue Tyler?

Thanks or the input guys I'll finally have some time this weekend to look into this issue I did notice my prop spacer is missing, guess the prop shop guys forgot to put it back on, hopefully that was the issue

Do you mean the thrust washer behind the prop (lower unit side) or the washer behind the nut? Most certainly in either case your prop would be floating on the prop shaft. If the thrust washer was missing the barrel of the prop could have been rubbing the lower unit case, not a good scenario.

Call those Bozos up and make them give you a new one.....gosh I just loathe poor service for premium payment. Reminds me of the time I had to explain the process for a front end alignment on a 4x4 to a Toyota service tech and SM after they told me a comprehensive rebuild was in order that something was bent on a perfect truck.