Turbocharger Sounds: What to Listen For

Hello,

I have a Golf III 1.9 TDI, manufactured in 1994, with 200,000 km on the odometer. The engine is original. I mostly drive on the highway. For some time now, there has been a whistling noise, up to approximately 2000 RPM, which is likely coming from the turbocharger. It sounds like a turbine.

My questions:
- What is the reason for that?
- How much longer can this continue before it turns into a serious defect?

Update: Does anyone else experience this turbine-like noise? It sounds sporty, but it can't be normal. I didn't hear it before. My car doesn't rattle, though...

Best regards,
I'm sorry, I don't understand. Can you please rephrase your request?

Hi,

First of all, the turbo is a turbine!! It's therefore reassuring to hear the noise. However, if the noise is too loud or turns into a squealing or rattling sound, then I would be concerned.

If the whistling sound was quieter before, I would check the hoses from the intake manifold, through the intercooler, all the way to the engine for any leaks.

hello!
Great that someone has addressed this topic. Unfortunately, I have a rattling noise coming from my turbo! I read somewhere that it could be a problem with the bearings.
In addition, there are oil leaks on the charge air cooler!
What could that be?
Best regards, Thomas.

Hi.

External oil seals typically indicate leaks in the pressurized area. The fact that oil is being forced out (which comes from the KGE) is perfectly normal.

In what situations does your charger make that rattling noise? Can you intentionally trigger it? And why are you so sure it's the charger and not something else?

It doesn't always have to be the charger...
'Recently, I've been hearing a rattling noise coming from my car. It's fairly easy to pinpoint because it's loudest when the engine is idling, and it can also be reproduced by tapping on certain areas (with the engine off).'

Werner.

'My catalytic converter is also rattling! When I'm stopped and turn up the bass a little, I hear a rattling sound. I think it's also the catalytic converter.'
but what exactly?

It rattles, especially during full-throttle acceleration. I'm not entirely sure if it's coming directly from the turbocharger, but I suspect it is, because when the turbocharger whistles, it also rattles.

Hello,

I recently had a similar annoying rattling noise on my Passat 35i, 1Z -- it was particularly noticeable at idle.
After finding information in the forum's error database, I tapped the catalytic converter with a hammer while the engine was off.

I was quite sure that the catalytic converter was the problem, but after removing the exhaust pipe, a "shake test" revealed that it wasn't the catalytic converter itself, but this "flex pipe," approximately 12cm long and wrapped in steel wire mesh, that was loose or had too much play, and was therefore no longer dampening vibrations from the engine.

After replacing this part – which I luckily found on eBay – and doing a little welding, everything was definitely quiet again!

Best regards, Jürgen R.

I'm experiencing a turbine-like whining sound – from idle up to approximately 2000 RPM, which often disappears when the engine is hot – and a rattling noise when the turbocharger is at full boost.
Has anyone gained any insights into the origin of these symptoms?

Experience report:

I installed a VNT17 turbocharger in my Audi A4.
'The boost pressure was increased using two diodes (from Conrad) connected between the boost pressure sensor and...'
Control unit implements.

Unfortunately, one of the diodes failed, and unlike a 'normal' diode failure.
one of them became completely impermeable, which led to a pressure peak.
resulting in a pressure of 2.2 bar.
Fortunately, I had already implemented an LDA (Linear Discriminant Analysis) and recognized this pattern after 2-3 peaks.

Since then, the loader has been making a noise for about 2-3 minutes during the warm-up phase, in addition to the whistling sound.
There's also a turbine noise between the idle speed and 1600 rpm.

I'm looking forward to seeing how things develop further.

Best regards.

peter


edit:
Unfortunately, I can't say for sure whether the slower response time is purely subjective.
The desired pressure of 1.1 bar is still achieved at 1900 to 2100 rpm.

Hmm, like me, I also switched from VNT15 to GT1749VB.
However, the loader was used.
Sounds like that usually means something isn't good.

What surprises me is that there isn't actually any significant boost pressure in this area yet. So why are there these noises? I still hope it's just something like a spring or a tensioner roller...

Marzocchi wrote:

What surprises me is that there isn't any significant boost pressure in that area yet. So why are there these noises? I still hope it's just the tensioner or idler roller or something like that...

Roller noises, etc., can be "easily" distinguished from the sound of the supercharger: they precisely and instantaneously follow any change in engine speed, while supercharger noises always (more or less) lag behind.

Especially in higher gears, the engine noise changes very little with short load changes, while the turbocharger makes a noticeable "whooshing" sound as it goes up and down.

"So, the whining sound is definitely speed-dependent, but as I said, I mostly hear it in the lower three gears. And even at those speeds, there's not much pressure built up (I don't need to accelerate hard to provoke the noise) – it's noticeable from idle speed up to around 2000 RPM (with the loudest noise being above 1600 RPM)."

@Marzocchi

Perhaps the sound only leaves the audible spectrum at around 16 kHz/2000 RPM, but it's still there! A dog would probably still notice it.

When I drove my old VNT15 out of the parking garage in the cold, with the window open, I could hear a whistling sound between 1000 and 1500 RPM on the tachometer. As the turbocharger warmed up, and with increasing engine load noises and wind noise, the whistling sound disappeared.

My VNT17 from the ARL engine is longer and more prominent than the VNT15 from the AFN engine.