VTG Cleaning Issues: Troubleshooting Guide

Okay, here's a quick summary. A friend's VW Sharan was experiencing a lack of power. After some quick diagnostics, it was clear that the turbocharger's boost pressure adjustment was not working correctly. The VTG linkage wouldn't budge, even with force (we tried everything, from small syringes to large ones).
He happened to find a new turbocharger on an online auction site. After I disassembled it and cleaned the variable geometry turbine (VTG), it worked great and had no detectable play.
Now I have the original one here, and it's causing me some concern. After taking it apart, I discovered the following:

www.matthiasmann.com/Bilder/DSC00160.JPG
www.matthiasmann.com/Bilder/DSC00161.JPG


I can only say that the one from egedöns looked much better. Well, you're always happy to get your hands dirty, and that's how I started. None of the guide vanes on the adjuster could be moved. Not even a little bit. I soaked them overnight in diesel and cleaned them the next day with a toothbrush. They look great, except that all the guide vanes, except for one, can be moved very easily. Then I carefully tried to move them with pliers (at the back of the adjuster). No chance. Does anyone have any ideas? I was thinking about a heat treatment, but would that make sense? I don't want to break anything, because even if it's broken, you can still use it as a spare part if it works again.

Here's how it looks right now:

www.matthiasmann.com/Bilder/DSC00167.JPG

I am grateful for any advice!

Hello.
Definitely perfect for a thorough ultrasonic cleaning. X

Best regards, Robert.

matthiasTDI96 wrote:

Except for one guide fin, all of them can be moved very easily. I then carefully tried to move it with pliers (attached to the adjustment mechanism at the back). No chance. Does anyone have any ideas? What tools can be used to address this?

Hi Matthias,

If there's no risk of breaking anything (e.g., the material of the shovel), I would try using a very small hammer to gently tap the stuck shovel back and forth in the axial direction, in an attempt to "break" the blockage.
Try turning it repeatedly and use a rust remover to help.

A controlled heat treatment can be helpful, as the vanadium-titanium-germanium alloy needs to be heat-resistant up to approximately 700°C.

Yes, I was also planning to try that "hammer" method. You can't really work on the guide vanes, as I suspect there's a break there. It might be possible to adjust the rear part of the mechanism, but I'm still a bit hesitant to do it.
Ultrasonic cleaner... hmm, hadn't even thought of that. Maybe I'll bring it tomorrow and put it in the ultrasonic cleaner in the electroplating area. Do you think it will help? It seems like the coating is completely stuck, and you can see through it between the contact surfaces.
I've also tried using rust remover. In fact, I've practically emptied the entire gun cabinet trying different things... nothing has improved. And I haven't tried any mechanical solutions yet.

For Ulf Database, if you're still collecting:

3K Loader.
K39b 0005

VW Part Number 038 253 019H.

Exhaust turbine diameter: surprisingly, 39mm.
The inlet diameter of the compressor is 36.8mm, and it narrows down to approximately 33mm towards the compressor impeller.

I just pulled that thing out of the diesel bath, and look... diesel not only provides heat and helps things move, but now everything is working again. After a lot of back and forth, it's really smooth and buttery now.

But there's something else. This defect probably occurs more often. Is it possible to purchase that part shown in the photos separately? The 3k-warner website doesn't have any information, and turbodriven.com seems to be down today.

Does anyone have any sources? Maybe it will help someone.

Hello Matthias!

What kind of deposits were those? Was the TDI engine running on US diesel fuel? It looks like sulfur deposits, that's incredible!!!
As you may know, I recently had similar problems with the VTG (Variable Turbine Geometry) on my GT1749V. The adjustment mechanism was so stiff that it was almost impossible to adjust anything without assistance and brute force. Meanwhile, the VTG is moving again due to vacuum .

One more question, just out of curiosity: Was the donor vehicle a standard model or a tuned one?

Regards,
Alex.

Oops... I just realized you were waiting for a response.

I can't tell you for sure, but he always believed it was running on diesel. However, the VTG was definitely stuck in the "off" position when he arrived with the tractor, and he was puffing out smoke like a bonfire. He claimed to have been driving like that for a while. What made me suspicious about the deposits was all the white stuff. I also checked for coolant leaks but found nothing. The thing ran great after the repair, and he hasn't shown up again since.
The vehicle is not tuned.

The VTG only became operational after a long period of troubleshooting and ultimately, force. After that, everything worked perfectly. I found it absolutely convincing.

matthiasTDI96 wrote:

However, the VTG was stubbornly stuck in the "closed" position when the tractor arrived, and it was emitting a thick cloud of smoke.

So, a fog machine just because the VTG is constantly closed (maximum pressure build-up)? What color was the smoke?

As black as night... so, not exactly disco-appropriate.

Then, does "geschlossen" (closed) refer to a minimal pressure buildup, or what?

Herr Antje wrote:

So, does "geschlossen" mean a minimal pressure buildup, or?

Incorrect: https://community.dieselschrauber.org/en/viewtopic.php?t=10810

Question to the group:
How can a TDI engine produce black smoke (unburned diesel) due to a faulty VTG (Variable Turbine Geometry)? Could it be caused by back pressure from the exhaust system pushing against the EGR (Exhaust Gas Recirculation) system?
That would mean that the load (LD) is lower, so exhaust gases flow through the open EGR valve into the intake side and displace fresh air there.
Accordingly, the LMM signal should decrease -> the turbidity effect kicks in and prevents excessive soot formation.

Somewhat mysterious...

ulf wrote:

Herr Antje wrote: So, does "geschlossen" mean a minimal pressure build-up, or? Incorrect: https://community.dieselschrauber.org/en/viewtopic.php?t=10810 Somehow, it's puzzling.

Therefore, I thought that matthiasTDI96 might have accidentally mixed up the terms, because it also seemed puzzling to me... However, since he's a professional, he probably knows what he wrote. So, there must actually be an explanation for it. I'd be curious to know what it is.

Okay... this has to do with the fact that I'm not expressing myself clearly: then use the term "open" instead of "closed." When I said "closed," I meant minimal pressure buildup. I also haven't found a meaningful explanation for this "vestbrenn" position. I need to find a picture that shows it clearly... then we won't be talking past each other because I understood "closed" to mean something different... sorry.

matthiasTDI96 wrote:

By "with," I meant: minimal pressure buildup.

Okay, the "correct" terms aren't widely known yet... in older posts, I had written it the other way around.

"However, I believe that a TDI engine with a variable geometry turbocharger (VTG) should normally not produce excessive soot, even if the VTG is constantly in a fixed position. This is unless the engine has been poorly tuned, or the exhaust gas recirculation (EGR) system is stuck in the open position."

Yes, the EGR valve should have been closed, as I didn't change anything, and it worked later. I can't rule out a chip tuning modification, as I don't know the driver well. You never know what people do in their free time...
"There was a whistling sound when accelerating. I only drove it for 200 meters, and that's when I knew which direction to look for the problem. However, the owner seems to have driven it quite a bit, as my colleague had already asked me about two weeks before I saw the car what could be done if there were any problems. As mentioned before, the impeller blades were so stuck that vacuum alone wouldn't have been enough to free them. And please look at the photos again. My turbocharger definitely didn't look like that after approximately 60,000 km."