Annoying Hissing Noise (Vacuum Leak) in Dash Area

[Deano3350]

Hey guys,

My VS Berlina is doing something just to P me off. There is a hissing noise which sounds like it is coming from passenger side under the dashboard. This noise only happens when there is vacuum in the intake ie under load, so I cant pinpoint it myself as I have nobody to stick head under there while I drive. All Vents still work fine so it is not effecting the Climate control nor car performance, its just pissing me off as it is VERY loud going up hills.

I have removed glovebox and the cover above that so I can see the fan and couple other things, no obvious problems there.

The noise happens when the Climate control is also off so that sorta narrows it to a feet/master vacuum feed line problem if im not mistaken.

With glovebox removed it almost sounds as if its just behind the firewall.

Does anybody know where I should be looking and what steps I should take at this point? lines in the engine bay appear fine and there but I cant see where the solenoid box gets its line from.

Sorry for the short novel and any help would be appreciated.
Cheers

[HamaTime™]

I'm experiencing the same sort of thing myself...though I've had it vaccum tested and everything...nothing showed up. I've got the L67 OTR CAI on it paired with a K&N...but still....It's just Hissing...

Sorry for not answering your question...but I know exactly what your dealing with...

[vstfeas]

i had a hissing problem and thought the same thing but i actuly found out it was my belt pullys needed replaceing it maybe worth looking at

[The1]

in the berlina's the vacuum box for the climate control vent controls sits behind the plastic tray below the tape/cd player, quite possible a hose has come off or the vacuum box needs replacing, you can still get them at holden i think and not to expensive.

Usually if the vacuum box is leaking you will get it changing from face vents to footwell when going up a hill or revving which creates more vacuum

[immortality]

yeah, it will be the control unit for the climate control. over the years shit builds up on the little valves and they don't seal properly causing the vac leak. mine does it too

[admir87]

sorry for hijacking... but what is the vaccum box? is that the soleniod box?

[Deano3350]

The vacuum solenoid was not the source of the hissing. There is a black tube behind vacuum solenoid that goes to what I assume is under the car is about 3 inches long and half inch diameter, it came out. I put that back in and sealed it with tape so the noise has quietened significantly but there is still a hiss louder than the system ever was only under load.
The remaining hiss seems to be coming from the box above and behind the solenoids where that tube connects to. Does anybody know what that box does? im guessing a line somewhere is clogged up with crap so its sucking air from somewhere else. Can anybody draw a rough drawing of all the vacuum lines that are in the cabin?
Any help to finally fix this would be appreciated.

[Deano3350]

The vacuum solenoid was not the source of the hissing. There is a black tube behind vacuum solenoid that goes to what I assume is under the car is about 3 inches long and half inch diameter, it came out. I put that back in and sealed it with tape so the noise has quietened significantly but there is still a hiss louder than the system ever was only under load.
The remaining hiss seems to be coming from the box above and behind the solenoids where that tube connects to. Does anybody know what that box does? im guessing a line somewhere is clogged up with crap so its sucking air from somewhere else. Can anybody draw a rough drawing of all the vacuum lines that are in the cabin?
Any help to finally fix this would be appreciated.

[hako]

When the car is under load or accelerating, the vacuum is reduced...not increased. There is a vacuum reservoir ball under the passenger side headlight which stores vacuum for when the engine is under load and running with reduced vacuum. At idle the vacuum will be about 17 to 21 inches of mercury whilst at WOT it will be zero inches of vacuum. Back in the 50's when Holdens had vacuum operated windscreen wipers, whenever the engine was under load like going up a hill, the wipers slowed and sometimes stopped.