Turbocharger Whistle: G4, ALH Diagnosis

When the engine is turned off, a hissing sound can be heard from the turbocharger wastegate solenoid valve. This noise only occurs intermittently. All vacuum hoses are new, and there are no kinks in the hoses.
Der Fehlerspeicher ist leer und der Motor hat kein Tunning. The AGR is defective.
Does this noise indicate a soon-to-fail solenoid valve, or is it one of those noises that can be ignored?
The engine runs well overall, except for a few minor instances of overboost.

wutz wrote:

Does this noise indicate a soon-to-be-defective solenoid valve, or is it one of the noises that can be ignored?

It's hard to say... until this changes:

Quote:

Otherwise, the engine runs well, except for a few minor boost overshoots.

I wouldn't do anything yet, because many mechanics develop harmless noises over time.

However, if the turbocharger's boost pressure becomes less precisely controlled at some point (e.g., with larger overshoots or slower build-up), I would replace the valve – provided that the variable turbine geometry (VTG) mechanism is still operating smoothly.

Okay, so I'll leave it as is for now. Although I'm surprised that the noise only appears occasionally. It first appeared when the EGR valve failed on the vacuum side. But it probably shouldn't be related to that.

hello,

I also currently have an ALH that needs repair with a similar, but slightly different problem. I didn't want to start a new thread, so here are my questions...

I'm not really getting anywhere with this... The car sometimes doesn't really start pulling until around 2000 RPM, and it feels sluggish. Sometimes it's completely normal and it pulls normally even from 1500 RPM.

No soot, the speedometer reaches 195 like it used to when new, and there's no uneven acceleration.

The following parts have already been inspected and replaced:

- all vacuum pressure hoses.
- Air mass sensor.
- EGR valve


Checked:

- VTG is freely movable.
- No errors in the error memory.
- The entire charge air cooling system is completely sealed.
- Vehicle is not chipped.


Is it worth replacing a new N75 valve if no error codes are being displayed? For me, personally, an N75 valve with 180,000 km (approximately 112,000 miles) on it is essentially considered worn out.