Something is Rattling! :-(

mattfish11

Seaman Apprentice
Joined
Apr 17, 2006
Messages
33
Ok first off, this is a mid-size Mercury 40HP 2 stroke.

The past couple times out I've noticed a faint rattle or ringing of my motor at idle. It immediately stops when I put the motor in gear and doesn't recur until I'm back in idle.

I've narrowed it down to the lower unit and noticed there's some play in there, a tiny bit of play between the spline of the lower unit and the prop housing. I've also noticed a tiny bit of play in the shaft of the spline as it goes into the lower unit.

I'm assuming this should looked at by a professional? Is there anything you guys can think of that might be a quick fix (like - duh! should have thought of that). I've tightened the prop down good - and that doesn't eliminate the problem.

Any help here?!?

Thanks!

Matt
 

Wingedwheel

Lieutenant Junior Grade
Joined
Jun 16, 2009
Messages
1,071
Re: Something is Rattling! :-(

What does your LU lube look like? Can you see metal flakes in it?
 

mattfish11

Seaman Apprentice
Joined
Apr 17, 2006
Messages
33
Re: Something is Rattling! :-(

LU oil looks clean. Not milky, no metal flakes. Just replaced the oil. Hmmm.. guess I'm off to the mechanic, again.
 
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