Engine Noise

[Big Fire]

I just put my boat in the water for the summer and am hearing what I can only describe as what sounds like air flow or an somethng like an open valve coming from my motor. It seems to be coming from the throttle body area. Any ideas?

Thanks!!

[Ewok]

Check the flame arrester/throttle body air inlet area for some blockage or trash that might cause the air going into the engine to make that whistle sound.

[Z1Fan]

or the intake manifold, can you take a vacuum gauge reading and see if its steady or bouncing everywhere, readings should be around 18" of vacuum ...

[boatdr]

if you have a Merc engine you most likely need a new idle air muffler. It is just a small block of foam. Part #863829 it goes in the throttle body

[Big Fire]

Thanks for the responses everybody! It was in fact the Idle Air Muffler - a simple $1.50 part and fix. Running great!

[mdk681]

Sorry if I am thread jacking, but I have been trying to track down a whistle coming from somewhere in my engine compartment as of late too. I have tried cleaning the flame arrestor which did not help. It seems to only happen around certain low RPMs - like 700-1000 then it goes away. I have a 1999 21v Riders Edition with the 350 MAG MPI. Does this motor have the idle air muffler as well? Does anyone have a pic of where this is located so I can check mine...? Thanks in advance

[boatwakes]

In both cases it's the idle air control valve (iac) and those year mercs have the air muffler to dampen the sound but it's nothing other than annoying.