I have a '08 Mercury 50 hp 4-stroke outboard motor that is sqeaking (similar to an alternator belt on a car) when the motor is idling and/or in gear. I'm not at all familiar with outboards and not sure if there is a belt which would cause the squeaking noise. The squeak gets louder the higher the RPM's increase. Is anyone familiar with this issue and is it something of concern? The motor does not seem affected by the noise and starts/idles/runs great..Any suggestions?

no there is no belt on outboards. im really not sure what it could be so i would suggest you take it to your local marina and see if they could take a look hope this helps

There is a belt on all outboards it's the timming belt the squiking your hearing could be the timeing belt is slipping. Take the cover off motor start it and watch to see if it is slipping if so you will need a new one. this belt is under the recoil starter cover.  Some times they will get stuck and not turn at all.     MCOPELAND1

Thanks MCOPELAND, I've been told by several others that this may be the issue. I'll take a look at it.

Thought I'd update on the "squeaking" noise. Turned out the noise was caused from a lack of lubrication on a rubber bushing on the upper driveshaft, at least that's what I was told by the marine mechanic. The fix required a little grease and fixed the issue. Thank goodness the motor is still under warranty cause in order to get to the bushing, it required the removal of the lower 1/2 of the motor. The mechanic said this is a common thing and is more of an annoyance noise. He said the bushing prevents water from penetrating the engine, but it is so high on the motor that if water did actually get that high, the motor would almost have to be submerged, which means I'd have much more things to worry about.

I'm not sure I'd be happy to know this bushing needed to be greased after 5 seasons of use and it required removal of the lower half of the motor - the warranty will be expired next time it causes a problem! I'd suggest you email Mercury Customer Service to see if this problem is inherent in the design of this motor, and if so who will pay next time - when the motor isn't still covered by your warranty. At the very least this will provide you with written correspondence and confirmation of the original problem for your records.