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  #1  
Old 16th August 2004
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Default Strange Whooshing Sound....

Ok, so I may not be an expert, but I'm sure I have never heard of someone having this problem before.

I'm sure some of you wonderful people (blatant suck-up ) will be able to advise...

When I release the accelerator (and there for the wastgate de-pressurises the system) I hear the normal Whoosh sound of the BOV. However, now, I also hear another sound after it, that is quite hard to describe so please bear with me. Imagine the release of air, in little bursts, at a high frequency of bursts. Loudish at the start, then gradually getting quieter. The whole event is over in about 1-2 seconds. I can replicate it again easily by boosting, then letting off the gas. Seems to do it more if I let of quickly, rather than slowly. Remember, I cannot hear the really sounds due to wind noise. Can't test it at stand still as the boost pressure doesn't build enough.
Boost to about 1 bar.

No mods to engine systems apart from Cat back 3"JT and nice blue vacuum lines.

My Simpleton's Diagnosis:
Could be the wastegate that at first opens wide to release the pressure, then hasn't got enough pressure to open prperly, so has to wait a few milliseconds for the pressure to open it.

Any help or advise would be GREATLY appreciated.
(Also if I do need a new wastegate/BOV has anyone got a spare?)

Mark

1994 9000 Aero
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  #2  
Old 16th August 2004
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Maybe it's the BOV "bouncing" before it closes. I'm not an expert by any stretch, but just put an atmospheric on and figure that might be it. Have you swapped it for a standard bypass just to check?
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  #3  
Old 17th August 2004
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I think what 'll have to do is look into finding a spare BOV. I really can't afford a new one so it'll be the breakers yards for me I think!

Mark
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  #4  
Old 17th August 2004
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Could be the sound of the turbo actually spooling down. You said it's at a high frequency of bursts. If there's some play in the turbo, it might make sounds similar to what you described at lower turbo rpm's. At higher rpms in the turbo, it'd just sound like a vibration and not really noticeable. Is there any sound on spool-up? Check for play in the shaft. Hopefully your turbo's not going bad, but it's just a theory. Probably just the wastegate/extraneous air excaping noises.
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  #5  
Old 17th August 2004
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There isn't the sound when it is spooling up, just when it's releasing the pressure. Indeed lets hope it's not the Turbo!

Mark
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  #6  
Old 17th August 2004
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mark you have mail
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  #7  
Old 11th January 2006
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I've got the same problem - anyone ever come up with a solution? Also, anyone have pictures of the vacuum line routing for a 93 aero?

Thanks,
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  #8  
Old 11th January 2006
AUSSIE JIM AUSSIE JIM is offline
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it hasn't got an old type dump valve on it do you? in about 93ish saab released a service mod on the valves. most of them had started mooing like cows so they replaced them with a different one which was a bit stronger and stopped the bounce in the valve. the performance of the old ones was not an issue, it was purely for noise.
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  #9  
Old 11th January 2006
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Cheers for the heads up - any ideas how I can tell whether this is an old one or not?
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  #10  
Old 12th January 2006
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i've only got the new number so if it is different on yours you'll know it's the old type. the saab part number- sa4441895
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  #11  
Old 12th January 2006
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To me it sounds like a noise I got when my bypass valve was dead, which is caused by the pressure wave reflecting off the throttle plate and hitting the spinning turbo impeller, which kind of chops the air making a noise like you describe.

I think the closest I could get to it is if you hold your hand about an inch in front of your mouth with your fingers splayed, purse your lips and blow a jet of air at your fingers while waving your hand up and down. Looks stupid but sounds about right.

Do your revs dip a lot when you come up to junctions etc?
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  #12  
Old 12th January 2006
donjohnson donjohnson is offline
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Hi guys,

Thanks for the information, i'll check the part number.

I've got another sound thats a little more intriquing... My cars an auto, when the transmission changes from 2nd to 3rd I get this really strange hoot sound - the only time it happens is a change from 2-3rd, never any other gear.

Anybody got any idea about this?

I'm servicing the car this weekend so i'll take a good look around.

I also have no idea when my CC pump is under the plastic sheet and would appreciate it if anyone had a photo of the location? Mine may be missing.

Cheers,
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  #13  
Old 12th January 2006
donjohnson donjohnson is offline
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My BPV is a Bosch 0280142103, anyone know anything about this part and whether I should try to find a replacement?
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  #14  
Old 13th January 2006
AUSSIE JIM AUSSIE JIM is offline
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ok, if the dump valve is failing you can tell by sucking on the hose and if it holds vacuum it's ok.the squeek from the box is quite common. the bands are getting worn in the box. there is a bottle of crap called anti judder that works.
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  #15  
Old 16th January 2006
donjohnson donjohnson is offline
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Thanks Jim, i've checked the valve and it appears to have vacuum. Gearbox squeak is still there - i've tried some additives from a local company but I can't seem to find the one that you recommend. I see that Saab recommend using a product called lubeguard though.

I'm just waiting for a box filter to arrive ($107 from Saab) and i'll give the oil a change out.

Cheers again.
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  #16  
Old 8th February 2006
donjohnson donjohnson is offline
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To follow up, I changed the oil which improved things but the ultimate fix was the Lubeguard additive... no more crazy noises from my gearbox now.

Cheers to all for the help.
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