1996 Mercury 25 hp screech noise

[TMW123]

Hi,
I have recently acquired a 25 hp mercy and it runs good at all rpm ranges except once in a while it will make a loud screech/chirp. Almost like a smoke alarm that's dying but louder. The noise lasts a second and the motor barely sputters and continues to run normally. This happens at idle maybe 3 times I'm out. Is this "lean sneeze" from a gummed up idle circuit or something else? Can the carb be removed and cleaned without adjusting timing after?

Thanks

 

[flyingscott]

That is usually a bearing in the crank or lower unit. Make a video of when it does that so we can hear it to be sure lean sneezes don't squeal/chirp.

 

[TMW123]

Getting a video will be tough because of how intermittent the issue is, but i will try. I thought it might be a bearing but heres a couple points that made me question that:

1. If it is a bearing why wouldnt the noise be more continuous instead of one, quick chirp and nothing for a long time and no issues at WOT?

2. Would the reed valve cause such a chirp during a misfire/sneeze?

Thanks and I appreciate the help!

 

[flyingscott]

You can look at the reed valves just take the carb off. Is the lower unit full of lube? Has the motor ever been overheated? A video would help

 

[roscoe]

Is this an electric start motor?
If so, could the starter be trying to engage and making contact with the flywheel?

 

[TMW123]

it is electric start. Is the starter attempting to engage a common problem?

 

[flyingscott]

Check the spring that holds the pinion gear down

 

[TMW123]

Just an update:
I turned the idle mix screw 1/8 turn rich and the chirp has not returned since.