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Discussion Starter #1
Hi

I think I have a vacuum leak behind the instrument panel (area), couse a hear a hissing sound from behind there when on boost.
Are there any vacuum hoses in this area? hard to get too?

Another strange sound is from the power steering, when i turn the steering wheel there is a low hissing sound.
But this hisssing sound existed before the first mentioned sound.

The boost gauge only goes into about 60-70% max towards red.


What do you guys think?????
 

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You have a vac line that goes from the engine to the pressure transducer & overboost pressure switch, then onto the boost gauge.

There are also vac lines that operate the heater flaps.
 

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as for your power steering hissing, not that this is much help, but i'm on my 3rd saab, and everyone of them have hissing steering. on my current one i'm going to try and drain then refill the fluid with new stuff, mine also has a leak (285,000 kms, what do you expect, its the original rack) if your rack is on its way out liek i think mine is, on cold mornings is the steering hard? do you have stiff spots? is the steering responsive and return to centre ect?
 

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does your boost guage work? The vaccum line could be disconnected from its coupling behind the instrument panel as stated above. That would be my first guess.
 

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Discussion Starter #8
woywitka said:
as for your power steering hissing, not that this is much help, but i'm on my 3rd saab, and everyone of them have hissing steering. on my current one i'm going to try and drain then refill the fluid with new stuff, mine also has a leak (285,000 kms, what do you expect, its the original rack) if your rack is on its way out liek i think mine is, on cold mornings is the steering hard? do you have stiff spots? is the steering responsive and return to centre ect?
The power steering has been hissing as long as ive had the car. It doesnt really bother me, but if it effect performance or if it is something serious then it would be nice to know.
The steering is harder i cold morning but nor for long, dont think i have stiff spots, havent really noticed it anyway, the steering is not very responsiv and does not always return to center by ut self.

The boost gauge works, i got it up over red before, now it is 60% into yellow max. ;oops:
 

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Discussion Starter #9
didnt find the cause of the sound, think ill have another look later.
cant really see what i am doing when working under the speaker.
but it seems like the sound defenetely comes from that area.
only saw one vacuum line behind the steering wheel and that one was for the left vent.

Any body gotta clue as to what can make the sound? sound like blowing air "hizzzz, hissss"
 

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There is a hub positioned more or less behind the stereo that many vacuum hoses attach to - you can see it in the link in my earlier post. I had a similar hiss from behind the dash on mine, which I at first thought was from behind the intrument panel. In my case the centre vents did not blow any air on the max <=> setting, which is usually a symptom of a vacuum leak, but it depends which hose blows off the hub. I tried to get access through the speaker grilles but could not reach, and my hands are too large to fit through the stereo slot, which I suspect is the case for anyone over 9 years of age. In the end I had to remove the dash, which is a pain, and as soon as I got it off I could see that one of the hoses had popped off the hub.

I have found a picture of the ideal person for this job :cheesy:

 

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Discussion Starter #11
Jezzadee said:
There is a hub positioned more or less behind the stereo that many vacuum hoses attach to - you can see it in the link in my earlier post. I had a similar hiss from behind the dash on mine, which I at first thought was from behind the intrument panel. In my case the centre vents did not blow any air on the max <=> setting, which is usually a symptom of a vacuum leak, but it depends which hose blows off the hub. I tried to get access through the speaker grilles but could not reach, and my hands are too large to fit through the stereo slot, which I suspect is the case for anyone over 9 years of age. In the end I had to remove the dash, which is a pain, and as soon as I got it off I could see that one of the hoses had popped off the hub.
im guessing your talking aboutvacuum distributor nr. 6 in picture?
The centre vents blow only one of the <=> setting, but blows well.
As for the hissing it is possible that my ears have tricked me on the location.
when i change setting on the hub there is a hissing sound, dont know if thats normal, i think it also did so before but im not sure. maybe the two sounds are linked.

I can actuall get my hand into the stereo slot but moving it around in there is just about impossible when my hand can barely squize in, and i cant really see if all the vacuum hoses are connected.
Ill try to check it out next time.

Did you hear the hissing sound constantly or only on boost?

Thanks for all answers
 

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Yes, one of the hoses had come off that hub marked no. 6. When you change the setting on the air distrubution dial it is normal that there is a hiss for a few seconds. The hissing was constant on mine - after switching the engine off it would continue for a few seconds before going quiet.
 

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Discussion Starter #13
i only hear the hissing sound when on boost, as if boost was leaking, but there doesnt seem to be a leak in the engine compartment and it sounds like it comes from behind the steering wheel, like a hose blowing out air.
 

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Find the line that goes from the inlet manifold into the car (there's only one) the other line you might find goes to the vac canister that operates the heater controls, this is inside the inner wing.

Block off this vac line & start the car, if the noise goes you know it's the line I mentioned at the begining of this thread.
 

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Discussion Starter #15
i only found 1 vac hose from the inlet manifold and it was connected to a plastic "bottle" on the passenger side (vacuum canister?), out of it was another vac line and this one continued into the coupe.

Tryed blocking them of one after the other without ay result. :cry:
 

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On the drivers side (Norway), passenger side (UK), there is the main throttle body. On the side of it is a 3 way T piece, near the coolant expansion tank. On that T piece junction one of the hoses goes back towards the cabin. Under the black circular brake booster there is a small hole where the vacuum line goes through the bulkhead/firewall and behind the dash. This connects to the overpressure switch. I found it helpful having removed the speaker grille to use a mirror on top of the dash to see where things were down there.
 

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Discussion Starter #17 (Edited)
Jezzadee said:
On the drivers side (Norway), passenger side (UK), there is the main throttle body. On the side of it is a 3 way T piece, near the coolant expansion tank. On that T piece junction one of the hoses goes back towards the cabin. Under the black circular brake booster there is a small hole where the vacuum line goes through the bulkhead/firewall and behind the dash. This connects to the overpressure switch. I found it helpful having removed the speaker grille to use a mirror on top of the dash to see where things were down there.
wiiiiiiiiiiiiiiii!!!

I found it, disconnected it and no more hizzing.
Thnx all
ill see if i can locate the leak, does it matter if i just disconnect the line? except the fact that it leaves the boost gauge and overpressure switch useless?
 
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