Mercruiser 140 idle squeak

pplundberg

Recruit
Joined
Jul 10, 2015
Messages
2
I have a 1986 Century boat with a 140 Mercruiser. I purchased this boat 4 years ago so my knowledge of history is limited to that. This engine runs very well! My concern: at idle speed and a bit higher, there is a rhythmic squeak. This is not a squeal, but sounds like a little chirp in rhythm with the engine. Thoughts? Should I be concerned?
 

airshot

Rear Admiral
Joined
Jul 22, 2008
Messages
4,222
How about the obvious.....fan belt in good condition and not worn out or loose? If you suspect the fan belt a simple trick is to rub the inside of the belt with a bar of soap, if the noise goes away then replace the belt. If the noise is still there then you need to look elsewhere. Not very often but I have heard of the harmonic balancer making a slight squealing noise a low rpm but that one might be a stretch. Those engines have a small timing plate very close to the balance wheel on the front of the engine and I have seen a couple cases where that plat has been bent and making a slight chirp sound every time it drags and touches.
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
I have heard alternators chirp as well. Usually easy to hear with a dowel touching it and your ear.
 
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