8hp 2-stroke - possible internal bearing issue, please help

[keeweechris]

Hi,

Fairly new to outboards, but spent a lot of time recently trying to fix this 8hp 2stroke of various issues. It's got a whine/squeal under load at mid revs. I can get it to happen a little, in a flush tank, but it really makes a sick noise on the water. Idles nicely, and the sound goes away at about 50% throttle onwards, but as it leaves idle, it happens. Power appears to be normal, no bogging down or anything funny. Gets a 3.4m inflatable with 2 adults & 2 kids up on plane reasonably smartly.

Things I've tried:
-swapping out entire lower leg
-Gear oil flush, new top and bottom gearbox seals, waterpump checked. All appears to be running smoothly down there
-Inspected driveshaft and prop shaft for bends and damage, running straight.
-Took powerhead off the frame, removed lower crank seal carrier, and gave it new seals (1 was damaged). Inspected lower crank bearing for play and damage, looks good.
-Even compression of about 110psi each cylinder

I'm wondering now if one of the piston bearings or the top crank bearing is stuffed. In flush tank, slowly increasing revs with cowling off, I can hear a rattle start up, then drop away as revs go down. Appears to be coming from the powerhead. Does this seem like symptoms of bad internals? I'm guessing I shouldn't be using it in this state?

Thanks for any advice. As I say, I'm new to all this, so appreciate the collective knowledge here.

Cheers
Chris

[99yam40]

a mechanics stethoscope might help pin point the area of the problem.
should get louder the closer you get to the problem when you place the end of scope on parts of the power head

[robert graham]

If you’re new to outboards, especially 2 strokes, then you”ll find that that they’re a bit noisy, making a variety of sounds that the newer 4 stroke motors just don’t make. Check by running the motor with the top cowling off looking for loose controls, wires, connectors, etc…..

[keeweechris]

a mechanics stethoscope might help pin point the area of the problem.
should get louder the closer you get to the problem when you place the end of scope on parts of the power head

Good idea, I'll get one of those, thanks.

[keeweechris]

Problem solved... Turned out to be a Singing Prop! Sounded like a dry bearing whine. It was a brand new Solas prop... switched back to the old beat-up yamaha one, and noise gone. Go figure.

[99yam40]

thanks for the update,
very strange about the prop causing it