New "Hissing" Sound - 2003 Liberty Sport

[cbc58]

A few weeks ago we started to get a hissing sound that appears to be coming from the drivers side somewhere - more towards front of car it seems. It is a constant hiss that appears after the car has been running about 5 seconds, and lasts once it's turned off for a few seconds. Guessing this is probably a vacuum/pressure leak somewhere - but I don't see anything looking from up top - where would the most likely culprit be to look or best way to diagnose? All hoses are original.. Tks

 

[LibertyTC]

Interesting.
If it still hisses after shutting jeep off, with the hood open, can you tell more clearly where it may be coming from then?
Look for any cracked or broken lines around the firewall, the intake and other areas.

 

[turblediesel]

Spray small shots of WD40 around where you think the leak might be at idle. If the rpms go up you're close.

 

[cbc58]

Thank you for the suggestions. I have looked along the firewall and have not found anything. Also crawled under and looked but nothing found yet. Tempted to buy a stethoscope...

 

[LibertyTC]

They are not that expensive and may help.
The one I have has the 2nd extender, which is good.

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[turblediesel]

Could also use a long screwdriver, putthe tip where you want to listen and the handle up against the little bump in front of an ear-hole closing it. Keep your long hair out of the moving parts.