Mercury 60 FourStroke EFI - oil sump modification
I have just got my boat back from my local Mercury dealer after experiencing a very loud squeaking noise generated when the engines hot - very similar to that made by a slipping alternator belt on a car.
Anyway, Mercury say this has been happening on a small minority of their 60 F/ EFIs, apparently there is a tin plate between the power head and oil sump which resonates as the oil is sprayed onto it. They have a modified plate available to fit to engines with the above symptoms
Note:- It doesn't affect performance or damage the engine in anyway, so unless you engine is making the noise there is no need to worry.