2002 F350 7.3 220k miles. What would make a noise like a helicopter hovering under my hood. Sounds like its on the drivers side. It almost sounds like a miss more than an exhaust leak. Could that be the CAC Boot leaking? do they make a noise like that. Ive not noticed any real loss of power yet. Does anyone have any ideas?

 

It sounds kind of like when the helicopter blade is cutting the air. Seems to start and run ok just makes a little noise.

 

Can you hear it, looking at the motor when it's running? I know it's noisy under there, sounds like an air leak or the belt has a piece shredded hitting on something.

 

Yeah thats it. My wife says it sounds more like an air leak. My hearing is bad so I have to have her listen to stuff for me.