Theres a snake under my GTD!

[adekil]

Hi all,

Never noticed this before on any other car I have owned but when I start up the engine in the morning (when I notice it the most) there's a hissing noise under the chassis, anyone know what this is?

[2014GTi]

Sounds like the fuel pump, is it coming from under the rear passenger seats?

[monkeyhanger]

Maybe it is the ACC (or DCC) adjusting itself and you can hear the servos at work? I do wonder if it is in a state of relaxation when the ignition is off and then tenses up into its chosen mode. Or it could be some other hydraulic system pressurising itself.

[adekil]

It does appear to be coming from the middle to rear just under the back doors on both sides

I've only just recently noticed as I switch on the engine get out of the car to defrost the screens where normally i get in switch on engine and drive off

[Geomets]

That may be the air from the ventilation system as it is in max passing through the rear channels. There are the rear vents and the rear floor vents. That is probably what you hear.

[adekil]

This hissing noise appears to only happen when starting the engine after being switched off for a while.
I've been parked up at work for around 5 hours, switched on engine and hissing was there.
Switched off and went back 10 minutes later an no hissing, so it cannot be a leak as that would be permanent i guess.

maybe it is calibrating or something to that effect.

No one else on here noticed it with their cars? I have adaptive chassis control as my only extra, maybe its that.... 

[rocknob]

I think it's the fuel pump priming the system. My Scirocco does it as does my wife's Tiguan.

[adekil]

Thanks rocknob and others, my concerns about the car exploding have faded as it seems no one seems concerned this may be a fault, so I may swing by a VW garage at some stage though for peace of mind