Occasional Hissing from under dash..??

[P1CR]

any thoughts??

it happens every few minutes or so...

[WCURoverD90]

hmmm on a station wagon....Do the station wagons have the vents in the dash that you can open and close for more air circulation...if so you might want to check the alignment on them...If not you may have a seal or something missing...I am not real familiar with the SW's but i know on my ST that I had some water leakage and a hissing and the vents were out of alignment...after i tightend them up and aligned them i have had no further problems....

Jason Habbal

[rover4x4]

n-m

[P1CR]

Definately not the vents...


n-m??

[WCURoverD90]

I didn't know if the SW's even had the vents in them......I just know i had the same thing of my ST and when i adjusted the vents it went away

Jason Habbal

[P1CR]

I wish it was the vents. it's a very strange intermittent noise.

I've had some bad wind noise from them on occasion...

[rover4x4]

When do you notice it? what conditions?

[P1CR]

when I'm driving.

ha! but really, it seems to have started in the past few days, and just comes and goes every several minutes irrespective of speed, weather, etc.

[Mike Hippert]

N-m = no message, SW have vents though. have you popped the hood to see if you can tell what its coming from. Could be a bad vacuum line.

[P1CR]

Haven't been under the hood yet.

I'll check tonight.

I'm pretty sure it comes from the lower passsenger side dash area.

[P1CR]

Thanks for all the help everyone...much appreciated as usual

[RyanS]

I'm not sure if the 90's are any different than the 110's, but on my 110, there are vacuum lines running around inside the dash on the passenger side. They control the heater/defrost flaps. So like Mike suggested, you might have a vacuum leak. You might play around with your heater/ventilation controls to see if it affects it. I believe there's also a cable that controls the fresh air inlet in the heater box. Maybe this is out of adjustment or not working.

[wicks]

Sounds like you've got an ininvited passenger. Get your snake bite kit handy and lure him out with a salamander or lizard on a stick.

[snuffer]

It might be associated with the air conditioner if you have one.

Just a guess.

[P1CR]

I think it increases when I'm slowing down, or stopped.

this is driving me nuts.

[rover4x4]

here's a tangent but maybe powersteering? Or something with the AC?

[P1CR]

ok, it gets more weird.

the hissing continues for a few seconds after I turn the key off, then fades away.

What a strange riddle. I like the snakes in my dashboard thought. At least I would know how to get rid of the problem.

[RyanS]

It really does sound like a vacuum leak. The manifold vacuum is the highest when you're off throttle (idling/slowing), and it will bleed off if you have a leak when the source goes away (i.e. turning off the engine). A hose might've just come loose or maybe one of the ventilation damper actuators is leaking.

[P1CR]

That sounds about right. How exactly do get to that stuff? Is it just under the hood? or does it need to get on a lift??

[Mike Hippert]

Get under the hood and carefully feel/listen around for the noise. There are a bunch of hoses for the vacuum system, if you run your hand down the hoses you will feel a leak if there is one.

[P1CR]

great, I'll try it today...

thanks again guys!

[artm]

I recently had the hose from the right valve cover to the plenum break. I can't say that I heard hissing inside the truck but with the hood up I did. It's an L shaped hose.

Actually it was an aftermarket hose that failed. This one had a thinner size at the large end than the factory unit and was just on too tight.