Motor Vibration at High RPM

[Boosey]

This past weekend I noticed my outboard motor had an audible vibration noise above 5,000 RPM. Below 5,000 no vibration. What would be some likely causes of this. Bad prop??? It just stated happening. It's a 1999 150 Johnson Faststrike, aluminum prop. Thanks in advance.

[Fisher Dave]

Prop is a possibility, or something in the lower unit... that is where I would look 1st.

The motor being out of tune is also a slight possibility .. but I would heavily lean toward the prop and check to see if theres enough lube in the lower unit.

[delmuts]

i agree with dave. i'm surprise you are running an alum. prop. if you have a spare prop; change it and see if the vibration is still there. if it is then i would have the lower unit checked. it could be the start of a problem. if you find it early it could save you some money in repairs. if hte vibration goes away , then you know it is yur prop. it is possible to that your motor mounts may becoming a little loose and showing some vibration too. my $.o2! del