# 2004.5 GLI : air whoosh sucking noise on acceleration



## rodent (Mar 28, 2005)

Hi All,

A few disclaimers first:
I searched everywhere (I think archived posts are not in the forum yet after the switchover) as well other places online.
I have read the FAQ guide, which is how I learned about the pancake pipe
I have the shop manual for my car, and have done a little bit of troubleshooting as my schedule and toddler would allow.


Issue: 
When I accelerate I hear a loud whooshing sound in the front passenger side corner. 
It sounds almost like an airbox leak, but it is the wrong side, it sounds like air rushing through a pipe or baffle.
It follows acceleration, I can be in the higher RPMs but not accelerating and I don't hear it. As soon as I accelerate I hear it (builds for maybe a second, the full noise). As soon as I ease and stop accelerating it stops.
It only seems to happen under turbo load. When I test it in the garage I cannot make it happen. Likewise on the road with with the clutch depressed, I can rev to the top of the powerband and not encounter it.
It also sounds like pushing a lot of air through a fan, it wobbles just a little, maybe like a leak opening and compressing under suction? 
Interesting caveat to that: when I to a test rev to the the top of the power band 4-5.5K, I get a real nice little whoosh right at the end as I let off. Like a diverter valve, but it 'seems' (can't prove it) that the whoosh is much more pronounced than I remember hearing it in the past....like an import tuner, not a stock VW.

So, essentially I get a lot of noise on acceleration under load, and 'it seems' like a bit crisper/louder 'blow off' at the end of 'acceleration' with the clutch in, ie. no load.

Troubleshooting:
It is so airy and loud, that at first I thought it was coming from my AC spin, maybe free spinning or being forced to spin by a vent error. Because the air flow sounded that obvious in the passenger front seat area.
I did some testing in the garage and test runs, both conservative and aggressive to see behaviour
The noise follows as described above. It is also very audible outside the car. I can hear it loud at freeway speed, reflecting off underpasses, etc. It would even sound kinda cool/mean if it didn't happen during all acceleration. 
Boost seems a little off, but certainly not gone. Without a boost guage, I cannot tell if it is my perception from the noise or not.
I dug out the shop manual and starting some testing. 
I don't have exact page numbers, but I test voltage for both the wastegate and bypass valves, I think? On the 1.8t there was one connector listed as the testing point for both, and I got an acceptable range of 30 ohms. 
Then it recommended testing the push rod on an air something that connects to the wastegate on the back of the turbo (sorry for lack of details on this point; I am writing this at work without the service manual). According to the manual, that rod should move during the testing process, and as far as I can tell, it didn't. However, the testing procedure was nested with the one before it and started with a non-running car, then starting, then hitting max throttle. Because of the time of day, etc, and how much I was trying to diagnose, I am not 100% certain on this step.

Fears:
That rod not moving means a wastegate problem and probably a new turbo.

Hopes:
It is actually a bad diverter valve; can I test this physically at the valve? Do my symptoms even match?
After reading today, and the location and volume of the noise, I am hoping that a pancake pipe may be a candidate too?

This happened pretty much out of nowhere, started about two days ago. I had my toddler in the car and had the A/C on 4 to try and cool him down. I noticed it later that day and initially thought it was maybe a fan issue.
I recently changed to Amsoil, but would not expect any negative issues from that, and haven't seen any. An oil check shows all positive signs.


I would be appreciative of any help or suggestions on troubleshooting this further.


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## Low: i has it? (Dec 16, 2009)

Did you check to make sure it isnt a leak by the intercooler? There is a soft hose that runs into the lower intercooler hose(pancake pipe). That rubber hose has a ****ty clamp at the top were it connects to the hard pipe that sometimes fails. Maybe pull off the passenger side wheel and get in there an look.

I would check for a boost leak before anything. Even a small leak can make a lot of noise under load.
And i doubt its your Wastegate(which is pretty hard to move by hand)

Good Luck


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## DC Jetta Guy (Jul 31, 2004)

Yes, definitely check your pancake pipe area in the pass side wheel well. Is your car chipped? Do you notice a loss of power under maximum boost acceleration? Definitely sounds like you have a boost leak. Sounds like you are spraying an air nozzle when accelerating hard.


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## rodent (Mar 28, 2005)

No Chip, waiting until after warranty/60K/timing belt sort of stuff. At this point it is pretty stock mechanically, with less than 60K miles on it.

It feels like boost is a little off, maybe more in the top end. It does still boost, it just seems maybe that it takes a few more seconds to top the power band than it used to. My gut says there is less, but the difference is not so obvious that I am sure how much less.

Not sure if I should know...what is spraying an air nozzle?


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## youngwun200 (Jan 18, 2009)

im having a similar issue in my 01 1.8T, under load, after about 3k my boost comes down from the spike, and if i let off the gas, it will spike to 15, then drop to 10, and then it sounds like my DV is just blowing air from my turbo right to the atmosphere like....... HARRRD PULL, and then 5.10.11.12.13.14.15......10PSI.. WOOOOOOSSSHHHH, and if i let off and back on it spikes then WOOOOOSHHHH to 15 then right back to 10 sounding like an air compressor is spraying under my hoodon drivers side though... domnt know if it helps


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## JWoody (May 17, 2006)

20ae3294 said:


> Did you check to make sure it isnt a leak by the intercooler? There is a soft hose that runs into the lower intercooler hose(pancake pipe). That rubber hose has a ****ty clamp at the top were it connects to the hard pipe that sometimes fails. Maybe pull off the passenger side wheel and get in there an look.
> 
> I would check for a boost leak before anything. Even a small leak can make a lot of noise under load.
> And i doubt its your Wastegate(which is pretty hard to move by hand)
> ...


 -J


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## andrewtoussaint (Jul 1, 2010)

*Any more info?*

I'm getting the same exact thing ('03 Jetta 1.8T), but don't have the maintenance knowledge like some of you, so I'm not sure I followed the thread. 

What's the update? Have you all diagnosed this? How serious are the possible diagnoses?

I'm taking it in tomorrow to a trusted mechanic. For me, I'm driving from DC to Michigan and don't want to cause further damage.

Thanks for the help, 

Andrew


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## viperius (Nov 7, 2008)

My car does the samething I am 99% positive that it is the charge pipe that runs from the turbo to the intercooler. follow that pipe from the turbo and I am sure you will see where its leaking.


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## phatride (Jun 15, 2008)

i have the exact same problem!! my thread is about this too but i didnt know how to explain it.


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## MarkusWolf (Dec 10, 2001)

same here.


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## andrewtoussaint (Jul 1, 2010)

*No leaks for me, though*

I don't have any leaks...these would be visible under the car, correct? 

I'm thinking a warped blade, perhaps?


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## woteg (Apr 7, 2009)

mine started doing this today, gunna go check it out once it stops raining


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## phatride (Jun 15, 2008)

ok so i took that pan cake pipe thing off and the black rubber hose on top off and found that the o ring was melted a bit. so i went to vw and bought a new one for 7$ and replaced it. i got some of my power back but its still makeing some kinda noise. its a really laud sucking noise even when i rev it to only 1500 rpm. i think it comeing from top of the turbo? but not to sure yet. i have to let the engine cool down before i touch it again.


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