Strange sound exhaust when engine is off

[Feijen]

Hello,
When i stopt the car and the egnition is of (With the Keys out), i hear a noice out of the exhaust.
Likes a little blowing fan in the exhaust??
The sound was there for minuts, at least i disconnect the battery.
Anyone nows what the problemen is?
The car is a Mustang 4.6L V8 2008
Thanx for the answer.

 

[stkjock]

can you be sure it's from the exhaust? not the fan by the engine running a bit after the car is off, fairly common happening.

 

[86GT351]

Check your under hood fuse panel for this issue. Could be cooling fan due to an overheated circuit.

 

[Feijen]

I hear the sound in the exhaust,when i close with my hand the exhaust i feel a little pressure.
Is there a fan in the engine that works with the engine off and the keys out?
the engine was cold (+/- 3 minutes running) when i stoped the car.

 

[stkjock]

there's no fan in the engine, there are fans by the radiator at the front of the car

 

[Zach Baumann]

Kind of a long shot but maybe the radiator fan is on like stated above and forcing some air through the intake and through an open exhaust valve causing this. Again a long shot. Could also be the hot exhaust cooling off making noise.

 

[Cum Grano Salis]

Made me think too here. Suppose a Cat is completely plugged and you have built up exhaust pressure at inlet and bleeding off after through tailpipe(s)?

 

[JC SSP]

Funny I thought the same thing or an exhaust valve not seating properly and combustion chamber pressure escaping... Curious to hear the conclusion to this mystery... LOL

 

[Juice]

Odd for sure. I have never heard of an issue like this.
If the cats are clogged, you would know. Car would have very little power.
My thought was water/condensation in the exhaust boiling off, but even that is a stretch lol.