Engine Whine: Is It a Turbo Problem?

Hello, I'm hearing a howling or whining sound coming from the engine compartment while driving.

Okay, gib mir den deutschen Text, den du übersetzt haben möchtest.

I'm riding with very little throttle in a quiet street at around 1200 RPM, then I briefly increase the throttle to about 1400 RPM. When revving up and down, there's a howling sound.
I can reproduce the same sound between 1800 and 2000 UPM; it's not very loud, but it's clearly audible to my sensitive ears.

I suspect it might be the turbo, but it's not the typical whistling sound you usually hear from a failing turbo.
It also seems to me that it's louder when the engine is warm.

"If the car is not in gear when it's stationary, I can't reproduce the noise!"

What could that be?

Could this be related to the EGR valve that I sealed off a few weeks ago (by inserting a metal plate)?

I can't remember if it appeared at the same time.


Thank you in advance.

Sven.

Quote:

If no gear is engaged while the car is stationary, I cannot reproduce the noise!

Have you ever seen the boost pressure at idle?
I don't either, because there isn't one... and if the turbocharger can't handle it, it shouldn't complain (it's not a girl).

Quote:

What could that be?

The turbo .

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hello Sven,
Let's assume that it's the 1.9L engine with 96 kW today, and not the smaller SDI .


There are a total of 7 noises that are directly caused by the turbocharger.
e.g., imbalance, pulsation, constant tone, rotational noise, instabilities, etc.

The noise you described...
in two short speed ranges under load and as a function of temperature.
suggests a revolving sound.
That is to say, the turbine or compressor blades are stimulated to "oscillate."
There were a "relatively" large number of complaints regarding this issue from "demanding" customers concerning the Passat with a 96 kW engine.
There's not much you can do to the turbocharger itself; even replacing it may only provide limited improvement. What might help is disconnecting and reinstalling the exhaust system or the intercooler piping without any tension, as these components can act as resonators and transmit vibrations.
The noise is annoying, I've driven a similar Passat myself, but it doesn't affect the durability and has no impact on thermodynamics (fuel consumption, acceleration, etc.).

Sure, here is the translation of the text from German to English:

"Hello."
snowy

Ah ha!

Can the noise in a well-insulated 3C system sound similar to a gearbox noise?

"Mine does that under heavy load and at low RPMs. It sounds too smooth to be a real transmission whine; when you let off the gas, it's more like the sound of the turbocharger losing pressure."

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hello, I'm going to try to verschandeln the EGR valve today to see if the problem is caused by it being blocked.
The turbo is doing its job well, but it's quite noisy in those RPM ranges.

If the SDI had a turbo whine, I definitely wouldn't complain about it .
Would that be a T-SDI...?



I'll get back to you later...

.... Message:

I've now removed the metal plate from the AGR flange... and there you go, the howling is gone, or at least it can only be faintly heard if you know what you're listening for; but if you haven't heard it before, you won't notice it (well, that's quite a sentence, you know what I mean ).

@Martin

You could definitely mistake the noise for a quiet whining sound from the transmission or axles; I even briefly considered that possibility.


I'll probably reinstall the metal sheet this weekend, if the only drawback is the howling noise...


Thank you all.

Sven.






Sven.

Hello scrdel!

The explanation for your audio problem is quite simple:

With the EGR system deactivated, a significantly larger mass flow of exhaust gases passes through the turbocharger at low load levels, which gets it spinning properly. Furthermore, it is controlled quite aggressively based on a pre-defined map, because it needs to build up some pressure, even though there is normally very little exhaust gas flowing.
When the EGR system is inactive, the significantly increased mass flow, combined with the aggressive control of the variable turbine geometry (VTG), results in a noticeable overshoot of the boost pressure (relative to the target boost pressure) and corresponding noise generation.

Regards,
ALex

Many people are sealing their EGR valves, but I haven't heard of anyone who ended up with such acoustics afterward?!

It's clear that the turbo produces more exhaust gases. But is it harmful if the boost pressure then overshoots?

I'm wondering whether I should leave the EGR valve open?

Do you want to fix the intake passages but risk damaging the turbocharger, or do you want to verschandeln the intake passages and potentially have the turbocharger fail later?


Sven.

Hello,
A blocked EGR valve does not affect the lifespan of the turbocharger due to excessively high rotational speeds.
Since AGR (Abgasrückführung) is only implemented in areas where there's still plenty of room for improvement with the turbocharger speed...

Regards,
snowy