[jbmorris2001]

OK I have a 1999 B5 with an AEB engine. I have had this problem for a while but had forgot all about it as I have not been driving the car. Here is what I have found out so far, last year I heard what sounded like a blow off value, but I do not have one of them. I checked all the lines and went on for everything. Well that was last year. Here is what I know, I only here it in first, second and sometime in third. It has to be high rpms and here is the kicker I only here it if the AC is on.
Please if anyone has some idea on where to start looking please let me know as this year there is alot going wrong with the car and I'm starting with what I think is the simple.

 

[Steve in Chicago]

When do you hear the noise? While under load with the gas pedal down or when you let off the gas pedal?
Does this car have an automatic or manual transmission?
Can you record a video with sound and post it?
What exactly does it sound like?
Inspect every hose under the hood for splits/breaks/cracks/disconnect.
Is the check engine light on?
Scan for trouble codes and post up the list of code numbers.
Will it make the noise if the AC is off and you're accelerating hard (like 80% throttle)?

 

[vbora01]

My AEB is much louder with the A/C on and when kicking it into the higher revs. It seems to me that the additional heat from the condenser allows the clutch on the pulley fan to engage more, hence a large "woooooosshhhh" noise from starts or upper RPMs. That's just a guess, I've never tried to pinpoint it as a problem. Even the stock diverter valve, though quiet, makes a bit more noise if the turbo is pushing its conservative 7-8 psi into the engine at higher RPMs.

 

[jbmorris2001]

When do you hear the noise? While under load with the gas pedal down or when you let off the gas pedal?

The sound come when I shift from one gear to the next most of the time, but yesterday I heard it once under load

Does this car have an automatic or manual transmission?

Manual transmission

Can you record a video with sound and post it?

Do not think that I can record the sound and post it

What exactly does it sound like?

The best way to describe it is like a blow off value on sports car with a blow off value on the turbo

Inspect every hose under the hood for splits/breaks/cracks/disconnect.

I have gone over the hose a few times last year when I first heard the sound, I found nothing. I even changed the value as my car is very slow to get any power

Is the check engine light on?

No check engine light at this time

Will it make the noise if the AC is off and you're accelerating hard (like 80% throttle)?

I have not heard it with the AC off that I know, it took a while to figure out that if the AC is on I hear it

As I said I hear the sound in first, second and sometimes third when I shift. the sound is just like if I had blow off value on the turbo

 

[Steve in Chicago]

Check the small vacuum line that runs from the front corner of the intake manifold, across the front of the engine, down to the diverter valve. The best way to do this is to disconnect the hose from the manifold and attach a hand vacuum pump then pump it down. It should pump down and hold vacuum. If it does not hold vacuum then that hose is ruptured somewhere or the diverter valve is bad. If this is the case, the engine will make a whooshing/fluttering noise anytime you let off the throttle while in boost. This is called compressor stall or compressor surge and it's not good for the turbo.

When the AC is on there is an extra load imparted on the engine (it takes power to make the cold). The reason I asked about no AC but 80% throttle was to see if it would make the same noise if you loaded the engine heavily without the AC. Give it a try and see what it does.

Will it do it with the AC on and you rev it up while standing still in neutral?

Is it an air rushing sound or a pulley/belt/bearing sound?

What I do to post a video of something like this is take a video with a smart phone then upload it to YouTube (free). Then drop a link to the video in the thread. If you're not apt at such things maybe a friend can give you a hand.

Oh... and it's not value, it's valve.

 

[jbmorris2001]

ok here is what al I have tried in the last year.

I have tried to recreate this many times and did not have the AC and it never work henc the reason I'm just now finding the combination to recreate the sound.

I can not get it to do it in neutral, it has to be under a load and the RPMs above 45000, think that is the right scale.

Do not think that it is a belt, pulley, or bearing sound as it is more like the sound of high pressure suddenly escaping.
if you youtube

this is the closet sound I can find right now but mine is 90% at shift only and that is what I think is so strange it is not something that is constant as once the engine is warm it does not do it anymore we I might get once in a blue moon

Thanks for the correction and I will try to get a video soon but it will not be tomorrow as I have school all day

 

[Steve in Chicago]

So it mostly (almost exclusively) happens with a cold engine.

I'd check function of the diverter valve and if that passes, do a boost leak test.

 

[jbmorris2001]

ok I can do the boost leak test, and going to do the vacuum test tomorrow, but what is the function test?

 

[Steve in Chicago]

Check that it functions (works). See if the valve and the little hose hold vacuum. See if the valve opens when under vacuum.

 

[jbmorris2001]

update I checked the valve today including taking it off to make sure it works right and everything worked right.

Tested trying to make it do it in while parked and yes it did it but I had to get the rpms around 45 to 50000, which is alot higher then I wanted to do with it parked but yes I got it to do it a few time before it warmed up. Going to try tomorrow and see if it might be the AC pully or something else....

Thanks for all the help so far please keep the ideas coming...

 

[Steve in Chicago]

Try a boost-leak test next.

 

[vbora01]

Are you sure you're not describing a normal operating sound? The diverter valve is supposed to make this whooooosh noise to bleed the charge pressure back into the intake. In doing so, a lot of air passes through the valve making the noise. How long have you owned the vehicle?

 

[2bluepassat]

pshhhht sound

Mine does this too!

Here is my exact symptom.

Temperature outside is hot >80F. Car is just started after sitting overnight or for a few hours. AC on I drive it normal then get on it a little for some boost power. I then here a woosh or pshhhht or blow off sound like I am venting some overpressure.

I swapped diverter valve with other passat no change, did a boost check and found a leak at suction jet pump (3 way venturi looking thing). Replaced suction jet pump and I still have the issue.

If it is cold outside and not using AC and I get on the throttle I don't here it. No engine codes either.

 

[vbora01]

Can ya'll listen to the video closely at 0:10

Sounds like a normal operating DV

 

[jbmorris2001]

I think I might have an idea of it now that I got it to make the sound once what I was looking at it. It looked like the AC clutch was not engaged at the high rpm, and then as the rpm was dropping it engaged and it made something close to the sound. With all the data it sounds like this might be my problem. first started the AC is not pressurized so the AC cycles with the higher rpms. Only happens with the higher temp, heavier duty on the pump. Only happens when the AC is on, AC clutch...

Not sure if it is or not but I guess the next thing I'm going to do is see if I can change the AC clutch and hope that this fixes the problem, oh and hope it makes the AC work alot better

 

[GSO_Passater]

Check the "L" hose too.