DPF Not Fitting: Twintec on VW Passat 3BG - Rumble?

Hello fellow mechanics,

I would like to share my problem with the Twintec retrofit kit I purchased, which includes a DPF (Diesel Particulate Filter), an oxygen catalyst, and related components.

My vehicle:
VW Passat 3BG, manufactured in 2005.
1.9 TDI, 96 kW (AVF)
6-speed manual transmission.

Summary:
The storage unit must be shifted as far to the right as possible on the crossbeam so that the storage unit and exhaust system are under tension, in order to avoid a collision with the right-side transmission support.

Images:
Please see the attachments.


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

'Long version:'
Immediately after the installation by my trusted mechanic, I noticed an unpleasant rumbling sound at 1900 RPM. At that point, the vehicle had almost 190,000 kilometers on the odometer.
Above and below this RPM, the engine noise was noticeably quieter. It wasn't until 3800 RPM that a loud rumbling could be heard again.
It was obviously the case that the exhaust system was under stress. The workshop disassembled everything again and reattached it, but the rumbling noise was still there.
Following a phone call with Twintec, I was informed that there is a different bracket for the DPF (Diesel Particulate Filter) specifically designed for the 6-speed transmissions, and that this bracket has now been installed.
As I recently saw in the AKTE catalog, for example, with the 5-speed gearbox (FHN), the bracket, especially the one on the right side, is different from that of my 6-speed gearbox (GVS).

The rumbling noise at 1900 RPM was noticeably reduced. At speeds below that, it has become slightly louder. Overall, the engine noise is quite rumbly at less than 2000 RPM. In the range of 2000 RPM to 3200 RPM, it's pleasantly quiet as usual. From 3200 RPM to almost 4000 RPM, the rumbling becomes loud again, which is quite annoying at speeds above 160 km/h.

In the meantime, the engine mounts had failed, so I replaced both the engine mounts and the transmission mounts. Twintec also suspected that the engine mounts were faulty. However, these apparently are not the cause of the rumbling noise described above, as the acoustics improved only slightly, if at all, after the replacements.
In this context, I naturally took a look at the DPF (Diesel Particulate Filter).
As you can see, the exhaust pipe runs extremely close to the right-side gearbox support. To the right of the exhaust pipe, there is still a relatively large amount of space. However, the bracket on the crossmember appears to be tightened much too strongly. If it weren't so tightly fastened, the exhaust pipe would touch the gearbox support.


Conclusion:
It seems to me that the intermediate pipe is not suitable for my vehicle, or what do you think?
Has anyone had any experience with this before?

Furthermore, I find that the corrosion is quite severe, considering that this DPF (Diesel Particulate Filter) has only been installed for 30,000 kilometers and 6 months.


Okay, that was a lot of information. I would definitely appreciate any feedback you can provide in advance.

Best regards,
Matthias.

Hi,
In particular, picture 2 shows that the rubber bushing is stressed and already torn, as can be seen in detail in picture 1. Does this retrofit kit come from the workshop?
Sure, here is the translation of the text from German to English:

"vg" translates to "very good" in English.
Herbert.

Quote:

Conclusion: It seems to me that the intermediate pipe is not suitable for my vehicle, or what do you think?

No matter what, it doesn't matter.
If the part doesn't fit, you have to make it fit, which is often the case with exhaust systems purchased from aftermarket suppliers (which cost only a fraction of the original equipment price).
For a skilled mechanic, this shouldn't really be a problem. It probably just requires some tinkering.
Before that happens, or the part is replaced with a suitable one, there's no point in discussing the rumbling, buzzing, etc. any further.

@Herbert
What do you mean by 'retrofit kit'? Are you referring to the crossbeam that was replaced? This new crossbeam was sent to the workshop by Twintec.

@BM
Right, it makes sense to adjust the shape of the intermediate pipe.

@everyone
Twintec contacted me regarding the issue and advised that I should contact my workshop or another authorized service center, and that the technician should call the technical hotline.
I was already annoyed during the alternative traverse that Twintec refused to send it to me. It absolutely had to be sent to an AU workshop .

The following was stated:
'After consulting with our technical department, it is unclear why the exhaust system is so tightly fitted. However, it appears that not the complete revised mounting kit was used. Due to the severe corrosion, it is very likely that this is still the rubber mount of the first generation of particulate filters.'

The workshop installed exactly the parts they received from Twintec. However, I find it strange that Twintec thinks the problem can be solved with a modified bracket, because a new bracket won't prevent the need to push the exhaust pipe to the right. Unless the bracket is designed in such a way that it pushes the exhaust pipe significantly upwards, which would likely cause problems elsewhere.


At least they checked to see if there were any corrosion issues.
Despite this, the original intermediate pipe was in better condition after 6 years and nearly 200,000 kilometers of use, compared to the Twintec one after only 6 months and 30,000 kilometers, in terms of corrosion.
Or have I completely remembered this wrong?!

Regards,
Matthias.

Hi there,
The complete TwinTec system is what's included in the retrofit kit. The question is: who bears the responsibility? Is it you, because you took the purchased retrofit kit to the workshop, or is it the workshop, which installed something offered by them?
"The crossbar shown here probably has nothing to do with the original condition; it looks very cheap. After some research, I'm wondering if an original crossbar even exists. If I understand correctly, picture 2 shows, viewed from the front, the transition from the intermediate pipe to the center muffler with the double clamp. Which parts of the exhaust system are still original, and which are from Twintec?"
Sure, here is the translation of the text from German to English:

"vg" translates to "very good" in English.
Herbert.

@Herbert
The retrofit kit had already been arranged by the workshop, meaning I paid the workshop for both the installation and the system itself. However, I specifically requested a Twintec filter from the workshop. Formally, the workshop is my point of contact because there's definitely a defect here, but morally, I also feel responsible.
The traverse shown in the picture definitely comes from Twintec.
Here's the translation:

'Twintec produces flex pipes, Okykat catalytic converters, intermediate pipes, DPF filters, and the aforementioned crossmember. The component located after the crossmember is actually the DPF. The rear silencer is positioned directly in front of the rear axle. Therefore, everything from the engine up to the DPF is made by Twintec. Behind that is the original VW exhaust system.'
It seems that not only is the crossbeam cheap, but also the intermediate pipe, which is already significantly more corroded after just 6 months than the original part from Volkswagen was.

What about other DPF manufacturers? Do they also produce such low-quality products?

I consciously chose not to go with HJS back then because they seemed very unsympathetic to me, both on the phone and at trade shows. Furthermore, it's likely that the CEO of HJS is politically active and therefore probably also a lobbyist. Incompetent politicians can only be convinced by lobbyists who pursue economic interests to support something as technically flawed as retrofitting DPFs in order to obtain a green sticker.
Well, that's kind of off-topic.

Have a nice weekend!
Matthias.

I have the OE conversion kit installed on my Passat, consisting of an Oxicat and DPF which now replaces the intermediate pipe, along with a rear mounting bracket for the (5-speed) gearbox. The manufacturer is HJS. It fits perfectly, there's no rattling, no corrosion or other problems. There are also no power losses or increased fuel consumption. It has been installed since autumn 2009. I have driven approximately 60,000 km with it since then. If I have time this weekend, I will take a picture of the system for you.
The Sharan mentioned above also has a HJS combination filter, and it hasn't experienced any corrosion problems so far.

EDIT: Here are the pictures. Considering it's been under snow for two winters, it looks pretty good.

Hello Steffen,

Thank you for the pictures.
Specifically, the bracket in picture 2 appears to be much more robust than the one on my Twintec version, although it looks different anyway with the 5-speed gearbox. However, the Twintec bracket is not different for the 5-speed gearbox variant either.

In image 1, which shows the DPF (Diesel Particulate Filter), I can't quite determine the exact position from which the photo was taken.

"The photo was taken between the doors, approximately behind the DPF filter, and then angled forward. It's not a combination filter. More would be visible if the rear underbody protection panel were removed. However, due to chronic time constraints, we unfortunately have to postpone that."

You're welcome, I understand now.
Overall, I find your bracket design very similar to the Passat models, where the intermediate pipe is also mounted (at least if I compare it to the AKTE diagrams).

Regards,
Matthias.

Hello everyone,

Now, after all this time, I have to revive this thread again.

It is now definitively confirmed that the exhaust pipe from Twintec has an incorrect shape between the oxygen sensor and the DPF, which would cause it to collide with the transmission support bracket, as this bracket is designed differently for the 6-speed gearbox.
To prevent the collision, the exhaust system needs to be 'pulled' to the right using the central support beam (see the image in the first post).

Meanwhile, the exhaust system has been reported as faulty. The complaint was initially rejected due to a difficult installation (although it could only be installed under tension).
A few months later, the central crossmember had sagged so much that it rattled when driving, as the exhaust pipe was hitting the transmission support.
Another replacement of the central beam didn't last long, and the mounting now looks like it does in the pictures again.

The three-year warranty has now expired, and I am really .


Has this problem really occurred for no one?


Regards,
Matthias.

P.S.: Does anyone else happen to have an original Oxicat lying around?

Quote:

Has this problem really not occurred for anyone else?

I don't understand the problem. What prevents the workshop from modifying the DPF so that it fits properly and sits securely where it should? I'm sorry, but I can't comprehend this.

Just make a couple of cuts with the angle grinder, bend the pipe back into shape, and then weld it back together – that should fix it.
Never mind – I already told you that two years ago.

Honestly, how can we help you if there's no willingness to do what needs to be done?

Thank you for your feedback.

Well, it certainly can't be due to my willingness. However, it is highly unusual that such rework is necessary for a part that is supposed to fit properly.

I lack the technical skills for the proposed and undoubtedly useful modification. Apparently, this wasn't a solution for the installation workshop either (especially since Twintec actually offered a three-year warranty on perfect fit). Unfortunately, the warranty has now expired.
And Twintec is unable to uphold the guarantees that were given.

One is theory, the other is practice.

A competent workshop would never have installed it while it was under tension; they would have immediately raised a complaint or offered suggestions and modified the installation.

That's because nowadays, workshops are almost exclusively staffed by employees who can only replace parts one-to-one and lack any other skills.

Sad but true.

Quote:

A competent workshop would never have installed it under tension; instead, it would have been immediately reported as a problem, or they would have collaborated and changed the entire setup.

. You can't deliver a vehicle like that - it's simply not possible. Unfortunately, we are increasingly finding that fewer and fewer mechatronics technicians, or whatever they call themselves, are no longer able to...
to identify simple issues and take corrective action.

If a tire is flat nowadays, they first read the error memory... but unfortunately, there's nothing in it.

Yes, I completely agree. It would have been a mistake to complain about the whole thing during the initial installation, before the car had even been driven 1 kilometer.

It's sad that the workshop didn't notice these issues themselves. At least I noticed them, but it doesn't really help much.

Following renewed contact with Twintec, it has now been determined that:
'...Unfortunately, we cannot determine the exact cause of the problem from here. Therefore, I would like to ask you to take your vehicle to a workshop that can remove the faulty part as part of a warranty claim and install a new one...'

It will likely be determined again that the current clutch kit was installed under tension, which is actually correct. In my opinion, one of the 'Twintec experts' should go and inspect the installation situation on the vehicle to confirm this. They apparently haven't yet understood that the 6-speed transmission, or rather its right-hand bracket, is structurally different from the 5-speed transmission.