hissing sound from motor

[live2fish]

Yesterday I did an oil change, filter and gas filter, and lower end unit lube. Today I started the motor up to make sure everything was ok. Much to my surprise when I went to turn it off I now hear a hissing sound like its venting? I have never heard this when doing my change's before. Has anyone got any idea what it is ? I am hoping to go musky fishing in a few weeks so I hope its nothing major and expensive. My motor is a 150 hp merc.
thank you for any help you can provide.

youtube video of it:



The sound almost sounds like it was coming from the tube at the bottom of the item circled in the pic. I should have held my hand there to see if I could feel the air venting?

 

[EthanC]

That's your starter circled in the picture

 

[Jow]

My 115 pro xs does this. Has done it since new.

 

[live2fish]

My 115 pro xs does this. Has done it since new.

Has it always been loud? I don’t recall mine being so loud…. I think old age memory is starting to hit me ugh

 

[live2fish]

That's your starter circled in the picture

Thank you!

 

[live2fish]

proctor marine helped me out, its ok! its the AIC parking. Normal.... my memory is going to crap though since I don't recall it ever being that loud before with the cowl off.