I have this hissing noise, sounds like a small leak, not sure how to explain the noise. It's very prevelant when cruising down the highway, with the radio off and windows up. Sounds like it's coming from behind the radio. It slowly dies off as I come to idle/stop. Can't hear I think at idle. No adverse effects and it doesn't drive me crazy so I'll, live with it.

 

Sounds like a firewall leak

 

Well that hose wasn't damaged at all so most likely the dash is gonna have to be pulled

 

Not sure if you want to try this, but...

You could cut each vacuum line running through the firewall, with the intention of splicing it back together, to isolate which line (if any) is leaking. Cut each, one at a time, plug it off, and go for a drive. Splice them back together with a piece of tubing slipped over each end, maybe with a touch of RTV sealant.

 

All I know is, the next time my dash comes out, I'll be drilling a hole through the firewall specifically for the vacuum line, with a rubber grommet installed... how it should have been from the factory... tucking it through the A/C line opening against a raw edge was brainless.

 

Oh, but, they saved a whole nickel per truck by NOT drilling that hole......

 

Gotta love the way they make them, this is my first Dodge I've always been against them haha. Honestly so far any work on this thing has been a breeze I must say

 

Yup they sure did... yet they have a hole w/grommet into the cowl for the reservoir, that could have been bolted to the firewall.

 

I had time to drop the dash, this is all I can see. I can't locate any vacuum hoses besides the green one. The noise is coming from where the picture is showing. I'm almost positive it's the line going into the firewall

 

I cut and re-routed my vacuum line going through the firewall and it still does it. I didn't bother with the green one because I figured the actuator is working so it must have vacuum going to it? I'm really stumped on this, as the noise is coming from glovebox area. I checked vacuum lines under cowl and they checked out ok. Which way are the check valves suppose to be facing? I'm stumped, it sounds like a vacuum leak to me, it only does it when you hit the gas and only when your in gear doing it. It's very loud, and I feel a power loss from a dead stop. Maybe I just have wild vents? And the noise is the wild vents kicking in, but when I hear this sucking noise as the Rpms raise then I hear the wild vents kicking on.

Also props to Beeker for the awesome write up about removing dash. I literally had it apart in under 30 minutes, no cracks!