Hey All,

I'm stumped and hoping to find some help here. Recently had a hissing noise develop on the passenger side when accelerating. Discoveries so far as follows:

• Hissing occurs when RPM gets over ~1500
• Hissing only occurs when in drive or reverse
• No issues when in park or neutral
• AC on/off makes no difference
• Dripping water from the passenger side firewall once parked
• No impacts to engine temp or gas mileage

Truck Details: 2014 F150 Platinum Ecoboost

Any help/thoughts are appreciated!

Thanks,
Mack

 

Lots of suggestions on google.

Boost leak, to heater core hissing / leaking.

 

could be a vacuum leak as well.

 

Freak of nature here, gonna have to take it to a technician to HEAR the problem