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Discussion Starter #1
During hard acceleration I hear what sounds like a 'hissing whistle" should once the RPM gets up there. At the shift it goes away until the RPM climbs again.

Turbo or vacuum leak maybe?
 

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Check the "U" shaped fitting going from the air cleaner "thingy" to the turbo. If it's not connectd tight enough, you'll be able to hear the turbo wailing.
-Joe
 

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Discussion Starter #4
H-TownBenzoboy - 2/10/2005 8:03 PM

Check the "U" shaped fitting going from the air cleaner "thingy" to the turbo. If it's not connectd tight enough, you'll be able to hear the turbo wailing.
-Joe
Checked this about 6 months ago it wasn't on correctly. I heard the noise back then, but fixing this didn't change anything. The noise did stop for about 4 months, but is now back.
 

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I heard a spooling sound on the first few months I owned my car, then when I checked the U tube fell. Had a hard time putting it back on as the seals were shot, so I got new ones and installed them. Didn't fall anymore, no more hissing.

Another source of hissing could be your ACC, though. (sounds like opening a Coke bottle, only slowly) Sometimes the vents don't close fully or the vacuum lines can be heard at times. Mine does this too.

By the way, how is the vacuum system? No leaks or anything?
 

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After a good drive to LAX and back, I did notice a metallic whine (not a hissing whistle) as I drove along at 80MPH. But it wasn't as loud as when the U tube fell off. And yes it did sound like a turbine or something spinning really, really fast. So I believe that was the turbo.

Jrehm, when the car shifts, how low does the RPM drop to and at what point does the sound return when the RPMs climb up again?
 

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Discussion Starter #8
No tach, so couldn't say. When I'm really getting on it, the noise comes back fairly quickly after the gear change. It goes away immediately if I let off the throttle.

By the way, there were no vacuum leaks when I tested it a few weeks ago.
 

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jrehm - 2/11/2005 4:39 AM

No tach, so couldn't say. When I'm really getting on it, the noise comes back fairly quickly after the gear change. It goes away immediately if I let off the throttle.

By the way, there were no vacuum leaks when I tested it a few weeks ago.
OK here's what happens to my car, maybe you could compare it to yours.

When I zip about accelerating to 45mph or 50mph, the turbo kicks in at 2,000rpm and I feel a surge (like after getting off a dead spot). And when I reach 40mph the tach reads 2,000rpm. 45mph is around 2,250rpm and 50mph is 2,500rpm. So starting at 40mph the turbo kicks in, hence the sound. Maybe yours does this too?
 

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Your problem/noise does sound to me also like the turbo. Maybe the seal between your turbo and the intake manifold is bad and you are leaking boost out of there. Maybe see if you can feel air pushing out of that while you rev the engine. If you had a bad enough vacuum leak that you could hear it inside the car over the noise of the engine, chances are your power brakes would not be so power any longer. I have driven my car with just the shutoff valve vacuum hose disconnected from the main vacuum tube, just with this disconnected my power brakes were much harder and I could not hear any vacuum leak from inside the car.
 

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I love how after the turbo kicks in, then after a moment, it suddenly the car speeds up.

I like that blowing sound though, you hear it at like 2000rpm and increasing. It sounds like a blow off valve.
 

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Generally the rule is, if you hear much more than a faint whistle coming from your turbocharger you are leaking boost pressure, especially if what you hear resembles a blowoff valve. A blowoff valve allows unused boost pressure to be released when the engine is decelerating, therefore anything that sounds like that is boost leaking out before it gets inside your engine. It may sound cool, but it means you are losing power!
 

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karugs - 2/10/2005 9:34 PM

I heard a spooling sound on the first few months I owned my car, then when I checked the U tube fell. Had a hard time putting it back on as the seals were shot, so I got new ones and installed them. Didn't fall anymore, no more hissing.

Another source of hissing could be your ACC, though. (sounds like opening a Coke bottle, only slowly) Sometimes the vents don't close fully or the vacuum lines can be heard at times. Mine does this too.

By the way, how is the vacuum system? No leaks or anything?
If your U-tube has fallen, will that result in you not being able to reach top speed?
-Joe
 

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If you're U-tube is not properly installed, the result will be the intake of unfiltered air which is very bad for your engine and catostrophic for the fins on the turbine within your turbocharger.
 

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Stevenpfaff - 2/14/2005 7:39 AM

If you're U-tube is not properly installed, the result will be the intake of unfiltered air which is very bad for your engine and catostrophic for the fins on the turbine within your turbocharger.
Ok, I have a new rubber gasket for the U-tube connection to the air filter. The old rubber gasket was shot, and not doing its job. The helper at the parts dept. counter at the dealership told me that I should use some sort of lubricant on both side of the new gasket when applying it. I'm afraid to use WD-40, I've heard it does more harm than good. What's a good lubricant to use for this job?
-Joe
 

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H-TownBenzoboy - 2/14/2005 7:27 PM

Stevenpfaff - 2/14/2005 7:39 AM

If you're U-tube is not properly installed, the result will be the intake of unfiltered air which is very bad for your engine and catostrophic for the fins on the turbine within your turbocharger.
Ok, I have a new rubber gasket for the U-tube connection to the air filter. The old rubber gasket was shot, and not doing its job. The helper at the parts dept. counter at the dealership told me that I should use some sort of lubricant on both side of the new gasket when applying it. I'm afraid to use WD-40, I've heard it does more harm than good. What's a good lubricant to use for this job?
-Joe
Sweat!! I didn't use lubricant. Hehe!! That's why I had to squeeeeeze it in really hard [:D][:D]

By the way, make sure you install the lower opening first. The upper one seemed harder to install. And when the air cleaner is taken off, the U tube should be attached to the turbo inlet by itself. Maybe that would help
 

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It's just the larger, higher opening that needs a new gasket. I've checked the lower one, it's fine.
-Joe
 

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You could always apply a bit of motor oil or use silicone lubricant. White lithium grease or wheel bearing grease also make good lubricants.
 

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Discussion Starter #19
Brake fluid is the best lubricant for this sort of thing. Brake fluid won't cause the rubber to break down like petroleum based products.
 

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You are right about the brake fluid, however our air intake system has engine oil going through it so the rubber gaskets are designed to withstand petroleum so pretty much anything would work.
 
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